title: TLR and NLRP3 inflammasome-dependent innate immune responses to tumor-derived autophagosomes (DRibbles).
abstract: Autophagosomes derived from tumor cells, also referred to as defective ribosomal products in blebs (DRibbles), have been previously shown to stimulate potent T-cell responses and mediate tumor regression when used as therapeutic cancer vaccines in multiple preclinical cancer models. In this report, we investigated the underlining mechanisms by which DRibbles induced T-cell activation, particularly how DRibbles activated antigen-presenting cells (APCs). We found that DRibbles could induce a rapid differentiation of monocytes and DC precursor (pre-DC) cells into functional APCs. DRibbles triggered innate receptor signaling via Toll-like Receptors (TLR)-2, TLR4, TLR7, TLR8, and nucleotide-binding oligomerization domain-containing protein 2 (NOD2), but not TLR3, TLR5, or TLR9. DRibbles induced PBMCs to produce pro-inflammatory cytokines, such as IL-6, IL-10, TNF-α, and IL-1β. DRibbles induced IL-1β release from PBMC or THP-1 cells without LPS priming, but required the core machinery of NLRP3 inflammasomes. Active endocytosis was required for inflammasome activation and cross presentation, and blocking endosome acidification or the ER-associated degradation (ERAD) pathway resulted in opposite effects on these two processes. Our data show that DRibbles could induce strong innate immune responses via multiple pattern recognition receptors, and explain why DRibbles could function as excellent antigen carriers to induce adaptive immune responses to both tumor cells and viruses. In contrast to the well-established inhibitory effect of autophagy on the inflammasome activation of APCs, our study demonstrates that isolated autophagosomes (DRibbles) from antigen donor cells activate inflammasomes by providing first and second signals required for IL-1β production by PMBC.
authors.affiliation: Minigene Pharmacy Laboratory, School of Life Science and Technology, China Pharmaceutical University, Nanjing, PR China.|Laboratory of Cancer Immunobiology, Robert W. Franz Cancer Research Center, Earle A. Chiles Research Institute, Providence Cancer Center, Portland, OR, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Xing
authors.affiliation: Minigene Pharmacy Laboratory, School of Life Science and Technology, China Pharmaceutical University, Nanjing, PR China.
authors.forename: R
authors.initials: R
authors.lastname: Cao
authors.affiliation: Laboratory of Cancer Immunobiology, Robert W. Franz Cancer Research Center, Earle A. Chiles Research Institute, Providence Cancer Center, Portland, OR, USA.
authors.forename: H-M
authors.initials: HM
authors.lastname: Hu
mesh_terms: D000071182:Autophagosomes / Q000378:metabolism*; D045744:Cell Line, Tumor; D016207:Cytokines / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D055354:Exosomes / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D007113:Immunity, Innate; D007156:Immunologic Memory; D058847:Inflammasomes / Q000378:metabolism*; D018836:Inflammation Mediators / Q000378:metabolism; D053583:Interleukin-1beta / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008213:Lymphocyte Activation / Q000276:immunology; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein / Q000378:metabolism*; D009369:Neoplasms / Q000276:immunology*; D010587:Phagocytosis; D010750:Phosphoproteins / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology; D051193:Toll-Like Receptors / Q000378:metabolism*; D014763:Viral Matrix Proteins / Q000378:metabolism
chemical_list: D016207:Cytokines; D058847:Inflammasomes; D018836:Inflammation Mediators; D053583:Interleukin-1beta; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C453881:NLRP3 protein, human; D010750:Phosphoproteins; D051193:Toll-Like Receptors; D014763:Viral Matrix Proteins; C065418:cytomegalovirus matrix protein 65kDa; D046988:Proteasome Endopeptidase Complex