Regulation of autologous immunity to the mouse 5T4 oncofoetal antigen: implications for immunotherapy

Complex TNF-α B cell epitope MAP vaccine alleviates murine ulcerative colitis

The present study aimed to develop a tumor necrosis factor‑α (TNF‑α) B‑cell epitope/IL‑1β helper T lymphocyte epitope complex MAP vaccine for the alleviation of ulcerative colitis (UC) in mice. The B cell epitopes of murine TNF‑α (mTNF‑α) were predicted in silico and coupled with the universal interleukin 1β (IL‑1β) helper T‑cell epitope peptide VQGEESNDK to synthesize the eight‑branched MAP vaccine. Then, the immunological effects of the MAP vaccine were assessed in vitro and in vivo, as well as its impacts on DAI index, serum DAO levels, colon tissue tight junction protein amounts, ultrastructural changes, and MPO activity in BALB/c mice with UC. The amino acids LTLRSSSQNSSDKPV at positions 78‑92 of mTNF‑α may constitute the dominant B cell epitope. Based on this finding, an eight‑branched peptide structure, the TNF‑α B‑cell epitope/IL‑1β helper T‑cell epitope complex MAP vaccine, was synthesized. Indirect ELISA confirmed that MAP had a high affinity with commercialized mTNF‑α antibodies. Meanwhile, MAP induced high specific antibody titers in vivo, reduced the DAI score, serum MPO activity, colorectal lymph node colony count, ultrastructural injuries, colon tissue histological index score and MPO activity in UC mice, while increasing the expression levels of occludin, claudin1 and ZO1 in colon tissues. The synthetic complex MAP vaccine has good antigenicity and immunogenicity, and can alleviate UC in mouse models.

Molecular adjuvants that modulate regulatory T cell function in vaccination: A critical appraisal

Adjuvants are substances used to enhance the efficacy of vaccines. They influence the magnitude and alter the quality of the adaptive immune response to vaccine antigens by amplifying or modulating different signals involved in the innate immune response. The majority of known adjuvants have been empirically identified. The limited immunogenicity of new vaccine antigens and the need for safer vaccines have increased the importance of identifying single, well-defined adjuvants with known cellular and molecular mechanisms for rational vaccine design. Depletion or functional inhibition of CD4⁺CD25⁺FoxP3⁺ regulatory T cells (Tregs) by molecular adjuvants has become an emergent approach in this field. Different successful results have been obtained for specific vaccines, but there are still unresolved issues such as the risk of autoimmune disease induction, the involvement of cells other than Tregs and optimization for different conditions. This work provides a comprehensive analysis of current approaches to inhibit Tregs with molecular adjuvants for vaccine improvement, highlights the progress being made, and describes ongoing challenges.

Prediction and identification of B‑cell epitopes for tumor necrosis factor‑α

The aim of the present study was to predict and identify B‑cell epitopes for mouse tumor necrosis factor‑α (mTNF‑α). DNAStar and BcePred software were used to predict B‑cell epitopes for mTNF‑α. A predicted eight‑branch multiple antigenic polypeptide (MAP) was synthesized and used to immunize BALB/c mice, combined with a promiscuous helper interleukin‑1β epitope (VQGEESNDK, amino acids 163‑171). The serum titer was measured. The specificity and avidity were determined by western blotting and indirect enzyme‑linked immunosorbent assay (ELISA). Amino acids 54‑65 (MAP1) and 78‑92 (MAP2) of mTNF‑α were predicted as most likely to be B‑cell epitopes. Dynamic monitoring of antibody concentration demonstrated that MAP1 and MAP2 may induce the production of specific antibodies with a higher antibody level for MAP2. Furthermore, MAP1 and MAP2 were confirmed to induce mTNF‑α‑specific antibodies by western blotting. Indirect ELISA was used to confirm that MAP2 had the highest affinity with commercial anti‑mTNF‑α antibody. Amino acids 54‑65 and 78‑94 of mTNF‑α are B‑cell epitopes, wherein amino acids 78‑94 have the strongest immunogenicity. The present study provides a theoretical basis for further research into the mTNF‑α polypeptide antibody and a B‑cell MAP vaccine.

5T4 oncofoetal antigen: an attractive target for immune intervention in cancer

The natural history of a patient's cancer is often characterised by genetic diversity and sequential sweeps of clonal dominance. It is therefore not surprising that identifying the most appropriate tumour-associated antigen for targeted intervention is challenging. The 5T4 oncofoetal antigen was identified by searching for surface molecules shared between human trophoblast and cancer cells with the rationale that they may function to allow survival of the foetus as a semi-allograft in the mother or a tumour in its host. The 5T4 protein is expressed by many different cancers but rarely in normal adult tissues. 5T4 molecules are 72 kD, heavily N-glycosylated proteins with several leucine-rich repeats which are often associated with protein-protein interactions. 5T4 expression is associated with the directional movement of cells through epithelial mesenchymal transition, potentiation of CXCL12/CXCR4 chemotaxis and inhibition of canonical Wnt/beta-catenin while favouring non-canonical pathway signalling; all processes which help drive the spread of cancer cells. The selective pattern of 5T4 tumour expression, association with a tumour-initiating phenotype plus a mechanistic involvement with cancer spread have underwritten the clinical development of different immunotherapeutic strategies including a vaccine, a tumour-targeted superantigen and an antibody drug conjugate. In addition, a chimeric antigen receptor T cell approach targeting 5T4 expressing tumour cells is in pre-clinical development. A key challenge will include how best to combine each 5T4 targeted immunotherapy with the most appropriate standard of care treatment (or adjunct therapy) to maximise the recovery of immune control and ultimately eliminate the tumour.

Single-cell gene expression signatures reveal melanoma cell heterogeneity

It is well established that tumours are not homogenous, but comprise cells with differing invasive, proliferative and tumour-initiating potential. A major challenge in cancer research is therefore to develop methods to characterize cell heterogeneity. In melanoma, proliferative and invasive cells are characterized by distinct gene expression profiles and accumulating evidence suggests that cells can alternate between these states through a process called phenotype switching. We have used microfluidic technology to isolate single melanoma cells grown in vitro as monolayers or melanospheres or in vivo as xenografted tumours and analyse the expression profiles of 114 genes that discriminate the proliferative and invasive states by quantitative PCR. Single-cell analysis accurately recapitulates the specific gene expression programmes of melanoma cell lines and defines subpopulations with distinct expression profiles. Cell heterogeneity is augmented when cells are grown as spheres and as xenografted tumours. Correlative analysis identifies gene-regulatory networks and changes in gene expression under different growth conditions. In tumours, subpopulations of cells that express specific invasion and drug resistance markers can be identified amongst which is the pluripotency factor POUF51 (OCT4) whose expression correlates with the tumorigenic potential. We therefore show that single-cell analysis can be used to define and quantify tumour heterogeneity based on detection of cells with specific gene expression profiles.

Targeting breast cancer vaccines to dendritic cells: improved immunological responses with less protein?

The central goal of cancer immunotherapy is to control tumors through the mobilization of the patient's immune system. Vaccines targeting the Her2/neu proto-oncogene have been tested with some early encouraging responses in breast cancer. However, a more effective set of vaccines targeting specific immune cell subtypes may provide a more potent means to stimulate anti-tumor immunity. Dendritic cell-specific antibodies fused with the Her2/neu protein proved effective at generating immune responses in preclinical models. Importantly, only low amounts of protein vaccine were required to generate this response, which has potentially significant implications for the future clinical development of Her2/neu-targeted vaccines and other vaccine targets.