Topical rather than intradermal application of the TLR7 ligand imiquimod leads to human dermal dendritic cell maturation and CD8⁺ T‐cell cross‐priming

Abstract

Toll-like receptor (TLR) ligands are attractive candidate adjuvants for therapeutic cancer vaccines, since TLR signaling stimulates and tunes both humoral and cellular immune responses induced by dendritic cells (DCs).Given that human skin contains a dense network of DCs, which are easily accessible via (intra-)dermal delivery of vaccines, skin is actively explored as an antitumor vaccination site. Here we used a human skin explant model to explore the potential of TLR ligands as adjuvants for DC activation in their complex microenvironment. We show that topical application of Aldara skin cream, 5% of which comprises the TLR7 agonist imiquimod, significantly enhanced DC migration as compared with that resulting from intradermal injection of the TLR7/8 ligand R848 or the soluble form of imiquimod. Moreover, Aldara-treated DCs showed highest levels of the costimulatory molecules CD86, CD83, CD40, and CD70. Topical Aldara induced the highest production of pro-inflammatory cytokines in skin biopsies. When combined with intradermal peptide vaccination, Aldara-stimulated DCs showed enhanced crosspresentation of the melanoma antigen MART-1, which resulted in increased priming and activation of MART-1-specific CD8 + T cells. These results point to advantageous effects of combining the topical application of Aldara with antitumor peptide vaccination.Keywords: Adjuvants r Aldara r Cross-presentation r DCs r Human skin r T-cell priming Additional supporting information may be found in the online version of this article at the publisher's web-site IntroductionVaccination is used to generate strong and specific immune responses against target antigens with minimal side effects. In particular, cancer vaccines aim to generate an efficient immune Correspondence: Prof. Yvette van Kooyk e-mail: y.vankooyk@vumc.nl response against tumor-associated antigens (TAAs), which will depend on the instruction of CD8 + T cells that can effectively eradicate the tumor [1]. However, cancer vaccines often show poor immunogenicity, making them dependent on adjuvants to induce an immune response and to avoid the generation of tolerance.Adjuvants consist of compounds that boost the potency, quality, or longevity of specific immune responses to antigens, but should cause minimal toxicity on their own [2]. They accomplish C 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.eji-journal.eu 2416 Cynthia M. Fehres et al. Eur. J. Immunol. 2014. 44: 2415-2424 these effects via the generation of antigen depots, attraction of an immune infiltrate, enhancement of antigen presentation through the activation of antigen-presenting cells (APCs) including the induction of appropriate costimulatory molecules and cytokines [3]. Toll-like receptor (TLR) ligands have been extensively studied as the latest generation of adjuvants [4]. These receptors are widely expressed by both immune cells such as dendritic cells (DCs), and nonimmune cells such as keratinocytes and fibroblasts [5]. TLRs represent a receptor family that recognizes a broad spectrum of conserved m...

Langerin-mediated internalization of a modified peptide routes antigens to early endosomes and enhances cross-presentation by human Langerhans cells

“…47 Bigger nanoparticles are less well internalized and cross-presented by LCs compared to small, soluble peptides. 29 These findings might explain the discrepancy found between the Van der Vlist study and the data presented here. In their study, the authors used relatively large MV particles and MV-infected cells that were not cross-presented in a langerin-dependent fashion, whereas we did show langerin-mediated internalization and cross-presentation of a small SLP in our studies.…”

“…Antigen presentation to human CD8 1 T-cell clones specific for MART-1 A CD8 1 T-cell clone specific for MART-1 [26][27][28][29][30][31][32][33][34][35] was generated and cultured as previously described. 30 The modified 16 aa-long MART-1 21-35 peptide (C-YTTAEELAGIGILTV) was added to 20 000 HLA-A2 1 LCs per well obtained after migration from the skin, at the indicated concentrations together with poly I:C (20 mg mL -1 ) for 3 h at 37 uC.…”

“…Real-time PCR analysis was performed as previously described using the SYBR Green method with an ABI 7900HT Sequence Detection System (Applied Biosystems). 29 GAPDH was used as an endogenous reference gene.…”

Extramammary Paget Disease of the Vulva: A Case Series Examining Treatment, Recurrence, and Malignant Transformation

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