Endoplasmic Reticulum-Associated Degradation-Dependent Processing in Cross-Presentation and Its Potential for Dendritic Cell Vaccinations: A Review

CircRNA-loaded DC vaccine in combination with low-dose gemcitabine induced potent anti-tumor immunity in pancreatic cancer model

Although promising, dendritic cell (DC) vaccines may not suffice to fully inhibit tumor progression alone, mainly due to the short expression time of the antigen in DC vaccines, immunosuppressive tumor microenvironment, and tumor antigenic modulation. Overcoming the limitations of DC vaccines is expected to further enhance their anti-tumor effects. In this study, we constructed a circRNA-loaded DC vaccine utilizing the inherent stability of circular RNA to enhance the expression level and duration of the antigen within the DC vaccine. Meanwhile we combined it with gemcitabine and validated their therapeutic efficacy in the Panc02 tumor model. We found that the use of DC vaccine alone can reach a tumor inhibition rate of 69%, and the effect was further enhanced when combined with gemcitabine, reaching a tumor inhibition rate of 89%. The combined treatment achieved a synergistic effect, which not only reduced immunosuppressive Tregs but also induced immunogenic cell death, leading to antigen spreading and reducing immune evasion caused by tumor antigenic modulation. As a result, the survival of the mice was significantly prolonged. Our research provides a promising approach for the clinical treatment of pancreatic cancer.

Extracellular Vesicle-Inspired Minimalist Flexible Nanocapsules Assembled with Whole Active Ingredients for Highly Efficient Enhancement of DC-Mediated Tumor Immunotherapy

The development of nanovaccines capable of eliciting tumor-specific immune responses holds significant promise for tumor immunotherapy. However, many nanovaccine designs rely heavily on incorporating multiple adjuvants and carriers, increasing the biological hazards associated with these additional components. Here, this work introduces novel flexible nanocapsules (OVAnano) designed to mimic extracellular vesicles, primarily using the ovalbumin antigen and minimal polyethylenimine adjuvant components. These results show that the biomimetic flexible structure of OVAnano facilitates enhanced antigen uptake by dendritic cells (DCs), leading to efficient antigen and adjuvant release into the cytosol via endosomal escape, and ultimately, successful antigen cross-presentation by DCs. Furthermore, OVAnano modulates the intracellular nuclear factor kappa-B (NF-κB) signaling pathway, promoting DC maturation. The highly purified antigens in OVAnano demonstrate remarkable antigen-specific immunogenicity, triggering strong antitumor immune responses mediated by DCs. Therapeutic tumor vaccination studies have also shown that OVAnano administration effectively suppresses tumor growth in mice by inducing immune responses from CD8+ and CD4+ T cells targeting specific antigens, reducing immunosuppression by regulatory T cells, and boosting the populations of effector memory T cells. These findings underscore that the simple yet potent strategy of employing minimal flexible nanocapsules markedly enhances DC-mediated antitumor immunotherapy, offering promising avenues for future clinical applications.

Flt3 ligand augments immune responses to soluble PD1-based DNA vaccine via expansion of type 1 conventional DCs

DNA vaccines are prospective for their efficient manufacturing process, but their immunogenicity is limited as they cannot efficiently induce CD8+ T cell responses. A promising approach is to induce cross-presentation by targeting antigens to DCs. Flt3L can expand the number of type 1 conventional DCs and thereby improve cross-presentation. In this study, we first constructed a DNA vaccine expressing soluble PD1 and found that the therapeutic effect of targeting DCs with only the sPD1 vaccine was limited. When combined the vaccine with Flt3L, the anti-tumor effect was significantly enhanced. Considering the complexity of tumors and that a single method may not be able to activate a large number of effective CD8+ T cells, we combined different drugs and the vaccine with Flt3L based on the characteristics of different tumors. In 4T1 model, we reduced Tregs through cyclophosphamide. In Panc02 model, we increased activated DCs by using aCD40. Both strategies triggered strong CD8+ T cell responses and significantly improved the therapeutic effect. Our study provides important support for the clinical exploration of DC-targeted DNA vaccines in combination with Flt3L.

The role of dendritic cells in cancer immunity and therapeutic strategies

Dendritic cells (DCs) are asserted as the most potent antigen-presenting cells (APCs) that orchestrate both innate and adaptive immunity, being extremely effective in the induction of robust anti-cancer T cell responses. Hence, the modulation of DCs function represents an attractive target for improving cancer immunotherapy efficacy. A better understanding of the immunobiology of DCs, the interaction among DCs, immune effector cells and tumor cells in tumor microenvironment (TME) and the latest advances in biomedical engineering technology would be required for the design of optimal DC-based immunotherapy. In this review, we focus on elaborating the immunobiology of DCs in healthy and cancer environments, the recent advances in the development of enhancing endogenous DCs immunocompetence via immunomodulators as well as DC-based vaccines. The rapidly developing field of applying nanotechnology to improve DC-based immunotherapy is also highlighted.

Targeting ubiquitin signaling for cancer immunotherapy

Cancer immunotherapy has become an attractive approach of cancer treatment with tremendous success in treating various advanced malignancies. The development and clinical application of immune checkpoint inhibitors represent one of the most extraordinary accomplishments in cancer immunotherapy. In addition, considerable progress is being made in understanding the mechanism of antitumor immunity and characterizing novel targets for developing additional therapeutic approaches. One active area of investigation is protein ubiquitination, a post-translational mechanism of protein modification that regulates the function of diverse immune cells in antitumor immunity. Accumulating studies suggest that E3 ubiquitin ligases and deubiquitinases form a family of potential targets to be exploited for enhancing antitumor immunity in cancer immunotherapy.

Heat shock protein 5 and inflammatory bowel disease

Inflammatory bowel disease is a kind of chronic recurrent intestinal inflammatory disease whose occurrence and development are affected by the integrity of the mucosal barrier. As the main component of the mucosal barrier, intestinal epithelial cells mainly include Paneth cells, goblet cells, etc. Heat shock protein 5 is a key factor for endoplasmic reticulum stress, and it affects the survival and apoptosis of intestinal epithelial cells mainly through endoplasmic reticulum stress pathways, and then participates in the process of inflammatory bowel disease.