Reovirus Activates Human Dendritic Cells to Promote Innate Antitumor Immunity

Abstract

Oncolytic viruses can exert their antitumor activity via direct oncolysis or activation of antitumor immunity. Although reovirus is currently under clinical investigation for the treatment of localized or disseminated cancer, any potential immune contribution to its efficacy has not been addressed. This is the first study to investigate the ability of reovirus to activate human dendritic cells (DC), key regulators of both innate and adaptive immune responses. Reovirus induced DC maturation and stimulated the production of the proinflammatory cytokines IFN-α, TNF-α, IL-12p70, and IL-6. Activation of DC by reovirus was not dependent on viral replication, while cytokine production (but not phenotypic maturation) was inhibited by blockade of PKR and NF-κB signaling. Upon coculture with autologous NK cells, reovirus-activated DC up-regulated IFN-γ production and increased NK cytolytic activity. Moreover, short-term coculture of reovirus-activated DC with autologous T cells also enhanced T cell cytokine secretion (IL-2 and IFN-γ) and induced non-Ag restricted tumor cell killing. These data demonstrate for the first time that reovirus directly activates human DC and that reovirus-activated DC stimulate innate killing by not only NK cells, but also T cells, suggesting a novel potential role for T cells in oncolytic virus-induced local tumor cell death. Hence reovirus recognition by DC may trigger innate effector mechanisms to complement the virus’s direct cytotoxicity, potentially enhancing the efficacy of reovirus as a therapeutic agent.

Multimodal immunogenic cancer cell death as a consequence of anticancer cytotoxic treatments

“…110,111 Although tumor-infiltrating DCs were impaired at maturation by immunosuppressive IL-10, PGE 2 , and transforming growth factor b produced from tumor cells, 112 unidentified components in the culture media from reovirus-infected cancer cells facilitated maturation of DCs. 113 Recent studies delineated that oncolytic viruses such as vaccinia, measles, HSV-2, and adenovirus cause the release of HMGB1. 64,65,114,115,116,117 Although HMGB1 interacts with viral components and may modulate viral replication, 117 the molecular mechanisms of how each oncolytic virus differentially produces these DAMPs remain largely elusive.…”

Reovirus Virotherapy Overrides Tumor Antigen Presentation Evasion and Promotes Protective Antitumor Immunity

“…Reovirus-initiated cytokine response in vitro has previously been reported (38,39); however, the comprehensive profile of such a response in different immune cell subsets or in vivo is still obscure. Using Antibody-based Quantitative (and Qualitative) Cytokine Array, we evaluated the expression of 60 cytokines following reovirus exposure of BMDCs, lymphocytes, and tumor cells in vitro or immunocompetent and immunocompromised mice in vivo.…”

“…Native B16 melanoma (B16) and Lewis lung carcinoma (LLC) were purchased from the American Type Culture Collection, whereas ovalbumin (ova)-expressing B16 (B16-ova; ref. Antibodies and reagents used in this study were purchased from different manufacturers as follows: eBioscience: Alexa 488-anti-CD11c, PE-anti-CD86, APCanti-CD40, APC-anti-CD80, PE-anti-mouse MHC class I molecule Kb bound to the peptide SIINFEKL (25-D1.16), unconjugated anti-mouse CD16/32, and unconjugated anti-mouse CD49d; Invitrogen: PE-anti-CD3, Alexa 488-IFN-γ, APC-anti-CD107a, unconjugated anti-mouse CD28, and 5-(and-6)-carboxyfluorescein diacetate (CFSE); BioLegend: PerCp-anti-MHC class II (H-2A/E) and PerCp-anti-CD90.2; BD Biosciences: PerCp-anti-CD8; GenScript: SIINFEKL (ova [257][258][259][260][261][262][263][264] ) and KAVYNFATM (LCMV gp [33][34][35][36][37][38][39][40][41] ) peptides.…”

“…B3Z is a genetically engineered T-cell hybridoma that bears ova-specific TCR and expresses β-galactosidase T-cell proliferation and IFN-γ/CD107a assay Lymphocytes were labeled with 1 μmol/L CFSE (32) and then stimulated with either SIINFEKL, tumor lysate (35), and control LCMV gp [33][34][35][36][37][38][39][40][41] peptide (5 μg/mL)-or UV reovirus [1 multiplicity of infection (MOI)]-pulsed BMDCs or concanavalin A (5 μg/mL), or left unstimulated. After 5 days of incubation, cells were harvested, stained with PE-anti-CD3 antibodies and analyzed.…”

Reovirus oncolysis: a brief insight on molecular mechanism and immunological aspect

“…Further, recent report studying the reovirus-induced immune responses during clinical trials showed increased number of CD3-CD56+ NK cells in the peripheral bloood mononuclear cells (PBMC) of the reovirus-treated patients (56). After culture with reovirus type 3 Dearing strain, human myeloid DC generated from PBMC get activated, produce proinfla-mmatory cytokines, e.g., IFN-α/β, TNF-α, IL-12 and IL-6, and further enhance the anti-tumor cytotoxic potential of NK as well as T cells (18). These studies have confirmed the ability of reovirus to stimulate different components of innate immunity.…”