Development of a dendritic cell-targeting lipopeptide as an immunoadjuvant that inhibits tumor growth without inducing local inflammation

Abstract

Materials used for the past 30 years as immunoadjuvants induce suboptimal antitumor immune responses and often cause undesirable local inflammation. Some bacterial lipopeptides that act as Toll-like receptor (TLR) 2 ligands activate immune cells as immunoadjuvants and induce antitumor effects. Here, we developed a new dendritic cell (DC)-targeting lipopeptide, h11c (P2C-ATPEDNGRSFS), which uses the CD11c-binding sequence of intracellular adhesion molecule-1 to selectively and efficiently activate DCs but not other immune cells. Although the h11c lipopeptide activated DCs similarly to an artificial lipopeptide, P2C-SKKKK (P2CSK4), via TLR2 in vitro, h11c induced more effective tumor inhibition than P2CSK4 at low doses in vivo with tumor antigens. Even without tumor antigens, h11c lipopeptide significantly inhibited tumor growth and induced tumor-specific cytotoxic T cells. P2CSK4 was retained subcutaneously at the vaccination site and induced severe local inflammation in in vivo experiments. In contrast, h11c was not retained at the vaccination site and was transported into the tumor within 24 hr. The recruitment of DCs into the tumor was induced by h11c more effectively, while P2CSK4 induced the accumulation of neutrophils leading to severe inflammation at the vaccination site. Because CD11b1 cells, but not CD11c1 cells, produced neutrophil chemotactic factors such as macrophage inflammatory protein (MIP)-2 in response to stimulation with TLR2 ligands, the DC-targeting lipopeptide h11c induced less MIP-2 production by splenocytes than P2CSK4. In this study, we succeeded in developing a novel immunoadjuvant, h11c, which effectively induces antitumor activity without adverse effects such as local inflammation via the selective activation of DCs.

Clients and Oncogenic Roles of Molecular Chaperone gp96/grp94

“…Upon encounter with specific microbial molecules TLR receptor are activated and initiate downstream signaling via MyD88-dependent or -independent pathways [41]. The identification of TLRs advanced the field of immunoadjuvants greatly, as most microbial immunoadjuvants work through TLR ligands [30], [42, 43]. Thus by controlling most TLRs as well as professional APCs, gp96 modulates both the innate and adaptive components of the immune system.…”

“…Moreover, current work utilizing genetic knockout (KO) strategies have revealed exciting cell-intrinsic roles of gp96 in innate immunity, inflammation, cytoprotection, development, stemness and oncogenesis [5, 18, 30–32]. This review will mainly focus on the cell-intrinsic roles of gp96 in cancer development, as the basic aspects of gp96 ER function such as calcium homeostasis, mechanisms of protein folding and quality control have already been reviewed extensively elsewhere [33, 34].…”

The TLR-2/TLR-6 agonist macrophage-activating lipopeptide-2 augments human NK cell cytotoxicity when PGE2 production by monocytes is inhibited by a COX-2 blocker

“…Designing of new adjuvants based on the structure of MALP-2 is also under way [11,36]. Our data revealed that NK cells are indirectly affected by MALP-2.…”

Development of a vaccine based on bacteria‐mimicking tumor cells coated with novel engineered toll‐like receptor 2 ligands

“…The following peptides and lipopeptides (purity >90%) were customized by Bio‐Synthesis (Lewisville, TX, USA) via Biologica (Nagoya, Aichi, Japan): OVA peptide, SIINFEKL; murine WT1 peptide, RMFPNAPYL; bio‐SK4 peptide, biotinylated‐SKKKK; bio‐MALP2 peptide, biotinylated‐GNNDESNISFKEK; bio‐SR11 peptide, biotinylated‐SRRRRRRRRRRR; bio‐SK11 peptide, biotinylated‐SKKKKKKKKKKK; P2CSK4 lipopeptide, P2C‐SKKKK; MALP2 lipopeptide, P2C‐GNNDESNISFKEK; P2CSR11 lipopeptide, P2C‐SRRRRRRRRRRR; and P2CSK11 lipopeptide, P2C‐SKKKKKKKKKKK.…”

“…When we examine the effects of vaccines after removal of free lipopeptide, the BMTC were administered twice intradermally. A lipopeptide dose of 10 nmol was validated previously using P2CSK4 as a positive control . An anti‐mouse PD‐L1 antibody (InVivoMab; 10F.9G2, Bio X Cell, West Lebanon, NH, USA; 200 μg per mouse) was injected intraperitoneally on the same day as the BMTC.…”