A composite MyD88/CD40 switch synergistically activates mouse and human dendritic cells for enhanced antitumor efficacy
Priyadharshini Narayanan, … , Kevin M. Slawin, David M. Spencer
Priyadharshini Narayanan, … , Kevin M. Slawin, David M. Spencer
Published March 7, 2011
Citation Information: J Clin Invest. 2011;121(4):1524-1534. https://doi.org/10.1172/JCI44327.
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Research Article

A composite MyD88/CD40 switch synergistically activates mouse and human dendritic cells for enhanced antitumor efficacy

Abstract

The in vivo therapeutic efficacy of DC-based cancer vaccines is limited by suboptimal DC maturation protocols. Although delivery of TLR adjuvants systemically boosts DC-based cancer vaccine efficacy, it could also increase toxicity. Here, we have engineered a drug-inducible, composite activation receptor for DCs (referred to herein as DC-CAR) comprising the TLR adaptor MyD88, the CD40 cytoplasmic region, and 2 ligand-binding FKBP12 domains. Administration of a lipid-permeant dimerizing ligand (AP1903) induced oligomerization and activation of this fusion protein, which we termed iMyD88/CD40. AP1903 administration to vaccinated mice enabled prolonged and targeted activation of iMyD88/CD40-modified DCs. Compared with conventionally matured DCs, AP1903-activated iMyD88/CD40-DCs had increased activation of proinflammatory MAPKs. AP1903-activated iMyD88/CD40-transduced human or mouse DCs also produced higher levels of Th1 cytokines, showed improved migration in vivo, and enhanced both antigen-specific CD8+ T cell responses and innate NK cell responses. Furthermore, treatment with AP1903 in vaccinated mice led to robust antitumor immunity against preestablished E.G7-OVA lymphomas and aggressive B16.F10 tumors. Thus, the iMyD88/CD40 unified “switch” effectively and safely replaced exogenous adjuvant cocktails, allowing remote and sustained DC activation in vivo. DC “licensing” through iMyD88/CD40 may represent a mechanism by which to exploit the natural synergy between the TLR and CD40 signaling pathways in DCs using a single small molecule drug and could augment the efficacy of antitumor DC-based vaccines.

Authors

Priyadharshini Narayanan, Natalia Lapteva, Mamatha Seethammagari, Jonathan M. Levitt, Kevin M. Slawin, David M. Spencer

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Figure 6

iMyD88/CD40-DC vaccination generates robust antitumor immunosurveillance in vivo.

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iMyD88/CD40-DC vaccination generates robust antitumor immunosurveillance...
(A) iMyD88/CD40-DCs enhance antigen-specific CD8+ T cell responses in vivo. E.G7-OVA tumor-bearing mice (n = 3) were immunized as described in Figure 5, C and D. 1 week later, PBMCs were analyzed for CD8+ Kb-SIINFEKL+ cells. Data represent mean + SEM. *P < 0.05; ***P < 0.0005 (2-tailed). (B) iMyD88/CD40-DC+CID delivery enhances tumor antigen–specific cytotoxic potential in vivo. Mice were treated as described above (n = 3). 2 weeks later, splenocytes from syngeneic C57BL/6 mice were pulsed with OT-I (SIINFELKL) peptide, CFSE-labeled (CFSEhi), and injected i.v. as targets. The next day, CFSE+ splenocytes were quantified. Histogram numbers represent percentages of CFSEhi cells. Data represent mean + SEM. *P < 0.05 (1-tailed). (C) Combined activation of innate and adaptive antitumor responses by iMyD88/CD40-DCs. Splenocytes from immunized mice were cocultured with 51Cr-labeled E.G7-OVA or control EL-4 (OVA–) or YAC-1 (NK targets) cells at different effector to target (E:T) ratios. Data represent mean ± SEM (n = 3). **P < 0.01; ***P < 0.001, iMyD88/CD40+CID versus all groups; 2-way ANOVA. (D) DC-secreted factors IP-10, IFN-γ, and IL-12 mediate antitumor effects of iMyD88/CD40-DC vaccine. SIINFEKL-pulsed, iMyD88/CD40-modified BMDCs from WT or IP-10, IFN-γ, IL-12p40, or IL-12p35 KO mice were activated with CID in vitro and in vivo following footpad injection. PBMCs were analyzed as discussed in A. Each data point corresponds to an individual mouse. Horizontal bars denote the mean for each group. Data represent mean + SEM (n = 5). *P < 0.05; ****P < 0.0001 (1-way ANOVA). Representative of 2 independent experiments.