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Mao C, Beiss V, Fields J, Steinmetz NF, Fiering S. Cowpea mosaic virus stimulates antitumor immunity through recognition by multiple MYD88-dependent toll-like receptors. Biomaterials 2021; 275:120914. [PMID: 34126409 DOI: 10.1016/j.biomaterials.2021.120914] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 05/10/2021] [Accepted: 05/19/2021] [Indexed: 02/07/2023]
Abstract
Cowpea mosaic virus (CPMV), a non-enveloped plant virus, and empty CPMV (eCPMV), a virus-like particle (VLP) composed of CPMV capsid without nucleic acids, are potent in situ cancer vaccines when administered intratumorally (I.T.). However, it is unclear how immune cells recognize these nanoparticles and why they are immunogenic, which was investigated in this study. CPMV generated stronger selective induction of cytokines and chemokines in naïve mouse splenocytes and exhibited more potent anti-tumor efficacy than eCPMV. MyD88 is required for both CPMV- and eCPMV-elicited immune responses. Screening with human embryonic kidney (HEK)-293 cell toll-like receptor (TLR) reporter assays along with experiments in corresponding TLR-/- mice indicated CPMV and eCPMV capsids are recognized by MyD88-dependent TLR2 and TLR4. CPMV, but not eCPMV, is additionally recognized by TLR7. Secretion of type I interferons (IFNs), which requires the interaction between TLR7 and encapsulated single-stranded RNAs (ssRNAs), is critical to CPMV's better efficacy. The same recognition mechanisms are also functional in human peripheral blood mononuclear cells (PBMCs). Overall, these findings link CPMV immunotherapy efficacy with molecular recognition, provide rationale for how to develop more potent viral particles, accentuate the value of multi-TLR agonists as in situ cancer vaccines, and highlight the functional importance of type I IFNs for in situ vaccination.
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Affiliation(s)
- Chenkai Mao
- Department of Microbiology and Immunology, Geisel School of Medicine, Dartmouth College, Hanover, NH, 03755, United States
| | - Veronique Beiss
- Department of Nanoengineering, University of California, San Diego, La Jolla, CA, 92093, United States
| | - Jennifer Fields
- Department of Microbiology and Immunology, Geisel School of Medicine, Dartmouth College, Hanover, NH, 03755, United States; Norris Cotton Cancer Center, Geisel School of Medicine, Dartmouth Hitchcock Medical System, Lebanon, NH, 03756, United States
| | - Nicole F Steinmetz
- Department of Nanoengineering, University of California, San Diego, La Jolla, CA, 92093, United States; Department of Bioengineering, University of California, San Diego, La Jolla, CA, 92093, United States; Department of Radiology, University of California, San Diego, La Jolla, CA, 92093, United States; Moores Cancer Center, University of California, San Diego, La Jolla, CA, 92093, United States; Center for Nano-ImmunoEngineering, University of California, San Diego, La Jolla, CA, 92093, United States; Institute for Materials Design and Discovery, University of California, San Diego, La Jolla, CA, 92093, United States
| | - Steven Fiering
- Department of Microbiology and Immunology, Geisel School of Medicine, Dartmouth College, Hanover, NH, 03755, United States; Norris Cotton Cancer Center, Geisel School of Medicine, Dartmouth Hitchcock Medical System, Lebanon, NH, 03756, United States.
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Albakri MM, Veliz FA, Fiering SN, Steinmetz NF, Sieg SF. Endosomal toll-like receptors play a key role in activation of primary human monocytes by cowpea mosaic virus. Immunology 2020; 159:183-192. [PMID: 31630392 PMCID: PMC6954739 DOI: 10.1111/imm.13135] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 09/20/2019] [Accepted: 10/14/2019] [Indexed: 12/30/2022] Open
Abstract
The plant virus, cowpea mosaic virus (CPMV), has demonstrated a remarkable capacity to induce anti-tumour immune responses following direct administration into solid tumours. The molecular pathways that account for these effects and the capacity of CPMV to activate human cells are not well defined. Here, we examine the ability of CPMV particles to activate human monocytes, dendritic cells (DCs) and macrophages. Monocytes in peripheral blood mononuclear cell cultures and purified CD14+ monocytes were readily activated by CPMV in vitro, leading to induction of HLA-DR, CD86, PD-L1, IL-15R and CXCL10 expression. Monocytes released chemokines, CXCL10, MIP-1α and MIP-1β into cell culture supernatants after incubation with CPMV. DC subsets (pDC and mDC) and monocyte-derived macrophages also demonstrated evidence of activation after incubation with CPMV. Inhibitors of spleen tyrosine kinase (SYK), endocytosis or endocytic acidification impaired the capacity of CPMV to activate monocytes. Furthermore, CPMV activation of monocytes was partially blocked by a TLR7/8 antagonist. These data demonstrate that CPMV activates human monocytes in a manner dependent on SYK signalling, endosomal acidification and with an important contribution from TLR7/8 recognition.
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Affiliation(s)
- Marwah M. Albakri
- Department of PathologySchool of MedicineCase Western Reserve UniversityClevelandOHUSA
- Department of Medical Laboratory TechnologyCollege of Applied Medical SciencesTaibah UniversityMedinaSaudi Arabia
| | - Frank A. Veliz
- Department of Biomedical EngineeringSchool of MedicineCase Western Reserve UniversityClevelandOHUSA
| | - Steven N. Fiering
- Department of Microbiology and ImmunologyGeisel School of Medicine at DartmouthNorris Cotton Cancer CenterLebanonNHUSA
| | - Nicole F. Steinmetz
- Department of NanoEngineeringUniversity of California San DiegoLa JollaCAUSA
- Department of RadiologyUniversity of California San DiegoLa JollaCAUSA
- Department of BioengineeringUniversity of California San DiegoLa JollaCAUSA
- Moores Cancer CenterUniversity of California San DiegoLa JollaCAUSA
| | - Scott F. Sieg
- Division of Infectious Diseases and HIV MedicineSchool of MedicineCase Western Reserve UniversityClevelandOHUSA
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