Toll-like receptor agonists shape the immune responses to a mannose receptor-targeted cancer vaccine

Previous studies have documented that selective delivery of protein antigens to cells expressing mannose receptor （MR） can lead to enhanced immune responses. We postulated that agents that influenced the MR expression level, and the activation and migration status of MR-expressing antigen presenting cells, would modulate immune responses to MR-targeted vaccines. To address this question, we investigated the effect of clinically used adjuvants in human MR transgenic （hMR-Tg） mice immunized with an MR-targeting cancer vaccine composed of the human anti-MR monoclonal antibody B 11 fused with the oncofetal protein, human chorionic gonadotropin beta chain （hCGβ）, and referred to as B 11-hCGβ. We found that humoral responses to low doses of B11-hCGβ could be enhanced by prior administration of GM-CSF, which upregulated MR expression in vivo. However, co-administration of the Toll-like receptor （TLR） agonists, poly-ICLC and/or CpG with B11-hCGβ was required to elicit Thl immunity, as measured by antigen-specific T-cell production of IFN-γ. The TLR agonists were shown to increase the number of vaccine-containing cells in the draining lymph nodes of immunized hMR-Tg mice. In particular, with B11-hCGβand poly-ICLC, a dramatic increase in vaccine-positive cells was observed in the T-ceU areas of the lymph nodes, compared to the vaccine alone or combined with GM-CSF. Importantly, the absence of the TLR agonists during the priming immunization led to antigen-specific tolerance. Therefore, this study provides insight into the mechanisms by which adjuvants can augment immune responses to B11-hCGβ and have implications for the rationale design of clinical studies combining MR-targeted vaccination with TLR agonists.

Recognition of HBV antigens and HBV DNA by dendritic cells

BACKGROUND: Hepatitis B virus (HBV) is a hepatotropic, noncytopathic, DNA virus which can cause acute and chronic infection. Viral persistence is associated with a weak or absent specific immune responses to HBV, particularly the cellular immune response. Dendritic cells (DCs) are professional antigen-presenting cells with a unique T cell stimulatory aptitude that play a crucial role in the instruction of adaptive immune responses upon infection. An impaired function of DCs was suggested by recent studies to account for the T and B cell hyporesponsiveness in chronic HBV infection. This review summarizes recent insights into the recognition of HBV antigens by DCs. DATA SOURCES: Studies were identified by searching MEDLINE and/or PubMed for articles using the key words 'hepatitis B virus (HBV)', 'dendritic cells', 'C-type lectins', 'mannose receptor', 'toll-like receptor', and 'dendritic cell-specific intercellular-adhesion-molecule-3 grabbing nonintegrin (DC-SIGN)' up to December 2009. Additional papers were identified by a manual search of the references from the key articles. RESULTS: DCs play an important role in the progress of hepatitis B, especially in the recognition of HBV. There are three main ways of recognition of HBV antigens by DCs. First, HBV DNA can be recognized by DCs through toll-like receptor 9 (TLR9) which activates the NF-kappa B signal pathway and p38 MAPK to up-regulate the expression of interferon (IFN) regulatory factor 7 (IRF-7) in a manner independent of type I IFN signaling, resulting in secretion of type I IFN and inflammatory cytokines, and induction of DC maturation and the adaptive immune response. Second, HBc/HBeAg cannot be recognized by DCs, but DNA or ssRNA encapsulated within HBcAg can be internalized by DCs through TLRs. Third, HBsAg can be internalized by DCs through the mannose receptor, which lacks the ability to induce DC maturation without the assistance of DC-SIGN. Meanwhile, there is some cross-talk among the three mechanisms, which induces an effective anti-viral response or HBV persistence. CONCLUSIONS: On the basis of these recognition processes, methods have been used to enhance the efficacy of DC-based vaccine against HBV and have been useful in the clinical application of HBV vaccine therapy. But the interactions between HBV antigens/HBV DNA and DCs are not clear, and cross-talk between TLRs and various ligands makes HBV antigen recognition by DCs more complicated. More efforts should be made to define the mechanisms and develop effective vaccines and therapies. (Hepatobiliary Pancreat Dis Int 2010; 9:584-592)

Clinical significance of loss of heterozygosity for M6P/IGF2R in patients with primary hepatocellular carcinoma

AIM:To investigate the relationship between loss of heterozygosity (LOH) for mannose 6-phosphate/insulin- like growth factor 2 receptor (M6P/IGF2R) and the outcomes for primary HCC patients treated with partial hepatectomy. METHODS: The LOH for M6P/IGF2R in primary HCC patients was assessed using six different gene-specific nucleotide polymorphisms. The patients studied were enrolled to undergo partial hepatectomy. RESULTS: M6P/IGF2R was found to be polymorphic in 73.3% (22/30) of the patients, and of these patients, 50.0% (11/22) had tumors showing LOH in M6P/IGF2R. Loss of heterozygosity in M6P/IGF2R was associated with significant reductions in the two year overall survival rate (24.9% vs 65.5%; P = 0.04) and the disease-free survival rate (17.8% vs 59.3%; P = 0.03). CONCLUSION: These results show M6P/IGF2R LOH predicts poor clinical outcomes in surgically resected primary HCC patients.

An antigen self-assembled and dendritic cell-targeted nanovaccine for enhanced immunity against cancer

The rise of nanotechnology has opened new horizons for cancer immunotherapy.However,most nano vaccines fabricated with nanomaterials suffer from carrier-related concerns,including low drug loading capacity,unpredictable metabolism,and potential systemic toxicity,which bring obstacles for their clinical translation.Herein,we developed an antigen self-assembled nanovaccine,which was resulted from a simple acryloyl modification of the antigen to induce self-assembly.Furthermore,a dendritic cell targeting head mannose monomer and a mevalonate pathway inhibitor zoledronic acid(Zol)were integrated or absorbed onto the nanoparticles(denoted as MEAO-Z)to intensify the immune response.The synthesized nano vaccine with a diameter of around 70 nm showed successful lymph node transportation,high dendritic cell internalization,promoted costimulatory molecule expression,and preferable antigen cross-presentation.In virtue of the above superiorities,MEAO-Z induced remarkably higher titers of serum antibody,stronger cytotoxic T lymphocyte immune responses and IFN-γsecretion than free antigen and adjuvants.In vivo,MEAO-Z significantly suppressed EG7-OVA tumor groth and prolonged the survival time of tumor-bearing mice.These results indicated the translation promise of our self-assembled nano vaccine for immune potentiation and cancer immunotherapy.

Marine-inspired molecular mimicry generates a drug-free, but immunogenic hydrogel adhesive protecting surgical anastomosis

Herein,we report the synthesis of a biomimic hydrogel adhesive that addresses the poor healing of surgical anastomosis.Dopamine-conjugated xanthan gum(Da-g-Xan)is fabricated using deep insights into the molecular similarity between mussels'adhesive and dopamine as well as the structural similarity between barnacle cement proteins and xanthan gum.The hydrogel mimics marine animals’adherence to wet tissue surfaces.Upon applying this adhesive to colonic anastomosis in a rat model,protective effects were shown by significantly improving the bursting pressure.Mechanistically,the architecture of Da-g-Xan hydrogel is maintained by dynamic intermolecular hydrogen bonds that allow the quick release of Da-g-Xan.The free Da-g-Xan can regulate the inflammatory status and induce type 2 macrophage polarization(M2)by specifically interacting with mannose receptors(CD206)revealed by RNA-sequencing and molecular binding assays.Consequently,an appropriate microenvironment for tissue healing is created by the secretion of chemokines and growth factors from M2 macrophages,strengthening the fibroblast migration and proliferation,collagen synthesis and epithelial vascularization.Overall,this study demonstrates an unprecedented strategy for generating an adhesive by synergistic mimicry inspired by two marine animals,and the results show that the Da-g-Xan adhesive augments native tissue regenerative responses,thus enabling enhanced recovery following surgical anastomosis.