Development of a Localized Drug Delivery System with a Step-by-Step Cell Internalization Capacity for Cancer Immunotherapy.

How to precisely reprogram tumor-associated macrophages (TAMs) and combine them with immunogenic cell death (ICD) is still a great challenge in enhancing the antitumor immunotherapeutic effect. Here, we developed a localized drug delivery system with a step-by-step cell internalization ability based on a hierarchical-structured fiber device. The chemotherapeutic agent-loaded nanomicelles are encapsulated in the internal chambers of the fiber, which could first be internalized by actively targeting tumor cells to induce ICD. Next, the rod-like microparticles can be gradually formed from long to short shape through hydrolysis of the fiber matrix in the tumor microenvironment and selectively phagocytosed by TAMs but not to tumor cells when the length becomes less than 3 µm. The toll-like receptors 7 (TLR7) agonist imiquimod could be released from these microparticles in the cytoplasm to reprogram M2-like TAMs. The in vivo results exhibit that this localized system can synergistically induce an antitumor immune response and achieve an excellent antitumor efficiency. Therefore, this system will provide a promising treatment platform for cancer immunotherapy.

Self-Blockade of PD-L1 with Bacteria-Derived Outer-Membrane Vesicle for Enhanced Cancer Immunotherapy.

The checkpoint inhibitor therapy that blocks programmed death-1 (PD-1) and its major ligand PD-L1 has achieved encouraging clinical efficacy in certain cancers. However, the binding of checkpoint inhibitors with other immune cells that express PD-L1 often results in a low response rate to the blockade and severe adverse effects. Herein, an LyP1 polypeptide-modified outer-membrane vesicle (LOMV) loaded with a PD-1 plasmid is developed to achieve self-blockade of PD-L1 in tumor cells. The nanocarriers accumulate in the tumor tissue through OMV-targeting ability and are internalized into the tumor cells via the LyP1-mediated target, subsequently delivering PD-1 plasmid into the nucleus, leading to the expression of PD-1 by the tumor cells. In addition, a magnetic particle chemiluminescence kit is developed to quantitatively detect the binding rate of PD-1/PD-L1. The self-expressed PD-1 bonded with the PD-L1 is expressed by both autologous and neighboring tumor cells, achieving self-blockade. Simultaneously, the outer-membrane protein of LOMV recruits cytotoxic lymphocyte cells and natural killer cells to tumor tissues and stimulates them to secrete IFN-γ  , improving the antitumor activity of the PD-1/PD-L1 self-blocking therapy.

Personalized Nanovaccine Coated with Calcinetin-Expressed Cancer Cell Membrane Antigen for Cancer Immunotherapy.

A cancer vaccine has been widely applied in clinical tumor therapy as one of the main strategies of immunotherapy. However, the traditional cancer vaccine for a single antigen has a low benefit rate due to the individual differences in patients. Here, we report a R837-loaded poly(lactic-co-glycolic acid) nanovaccine coated with a calcinetin (CRT)-expressed cancer cell membrane antigen for immunotherapy. The cell membrane antigen that possessed a complete antigen array was obtained by inducing immunogenic cell death in vitro, avoiding the severe systemic toxicity of chemotherapy in vivo. The nanovaccine codelivers the adjuvant R837 and the Luc-4T1 membrane antigen, triggering a personalized immune response to the corresponding tumor. Moreover, the calcinetin exposed on the surface of the nanovaccine induces the active uptake of dendritic cells, consequently enhancing the antitumor effect. Meanwhile, the nanovaccine activates immune memory cells to provide long-term protection. Our work provides a new strategy for a clinical personalized antitumor vaccine.

Polarization of Tumor-Associated Macrophages by Nanoparticle-Loaded Escherichia coli Combined with Immunogenic Cell Death for Cancer Immunotherapy.

The tumor immunosuppressive microenvironment greatly limits the efficacy of immunotherapy. Tumor-associated macrophages (TAMs) are the most abundant immunosuppressive cells in the tumor microenvironment, which can inhibit the tumor after converting it to an M1-like phenotype. In addition, immunogenic cell death (ICD) can increase the amount of T lymphocytes in tumors, activating antineoplastic immunity. Herein, tumor-associated macrophage polarization therapy supplemented with PLGA-DOX (PDOX)-induced ICD is developed for cancer treatment. The nanoparticles/bacteria complex (Ec-PR848) is fabricated for tumor targeting and TAM polarization, and PLGA-R848 (PR848) are attached to the surface of Escherichia coli (E. coli) MG1655 via electrostatic absorption. The toll-like receptor 7/8 (TLR7/8) agonist resiquimod (R848) and E. coli can greatly polarize M2 macrophages to M1 macrophages, while PDOX-induced ICD can also impair the immunosuppression of the tumor microenvironment. This strategy shows that tumor-associated macrophage polarization therapy combined with ICD induced by low-dose chemotherapeutic drugs can commendably enhance the efficacy of immunotherapy.

Bacteria-Based Cancer Immunotherapy.

In the past decade, bacteria-based cancer immunotherapy has attracted much attention in the academic circle due to its unique mechanism and abundant applications in triggering the host anti-tumor immunity. One advantage of bacteria lies in their capability in targeting tumors and preferentially colonizing the core area of the tumor. Because bacteria are abundant in pathogen-associated molecular patterns that can effectively activate the immune cells even in the tumor immunosuppressive microenvironment, they are capable of enhancing the specific immune recognition and elimination of tumor cells. More attractively, during the rapid development of synthetic biology, using gene technology to enable bacteria to be an efficient producer of immunotherapeutic agents has led to many creative immunotherapy paradigms. The combination of bacteria and nanomaterials also displays infinite imagination in the multifunctional endowment for cancer immunotherapy. The current progress report summarizes the recent advances in bacteria-based cancer immunotherapy with specific foci on the applications of naive bacteria-, engineered bacteria-, and bacterial components-based cancer immunotherapy, and at the same time discusses future directions in this field of research based on the present developments.

Development of a pH-responsive polymersome inducing endoplasmic reticulum stress and autophagy blockade.

Autophagy is involved in the occurrence and development of tumors. Here, a pH-responsive polymersome codelivering hydroxychloroquine (HCQ) and tunicamycin (Tuni) drugs is developed to simultaneously induce endoplasmic reticulum (ER) stress and autophagic flux blockade for achieving an antitumor effect and inhibiting tumor metastasis. The pH response of poly(ß-amino ester) and HCQ synergistically deacidifies the lysosomes, thereby blocking the fusion of autophagosomes and lysosomes and lastly blocking autophagic flux. The function mechanism of regulating autophagy was systematically investigated on orthotopic luciferase gene-transfected, 4T1 tumor-bearing BALB/c mice through Western blot and immunohistochemistry analyses. The Tuni triggers ER stress to regulate the PERK/Akt signaling pathway to increase the autophagic level. The "autophagic stress" generated by triggering ER stress-induced autophagy and blocking autophagic flux is effective against tumors. The reduced expression of matrix metalloproteinase-2 due to ER stress and reduced focal adhesions turnover due to the blockade of autophagic flux synergistically inhibit tumor metastasis.

Zinc protects against cadmium-induced toxicity by regulating oxidative stress, ions homeostasis and protein synthesis.

The widespread environmental toxin cadmium (Cd) is associated with numerous human diseases. The essential trace element zinc (Zn) strongly counteracts Cd-induced toxicity; however, the mechanism is incompletely understood. Here, we conducted RNA sequencing and bioinformatics analyses to determine the global gene expression profiles of yeast cells exposed to Cd or Cd plus Zn. We identified 912 Cd-induced and 627 Cd plus Zn-induced differentially expressed genes (DEGs). Adding Zn during Cd exposure efficiently reversed the expression of 92.1% of Cd-induced DEGs; that of 48.7% was entirely reversed. Gene Ontology, Cluster of Orthologous Group and KEGG Ontology analyses revealed that the response of yeasts to Cd or Cd plus Zn was mainly involved in metal-specific oxidative stress; energy production and conversion; ion homeostasis and ribosome biogenesis and translation. Exposure of yeasts to Cd plus Zn protected them from oxidative stress by efficiently inhibiting the expression of genes associated with Cd-triggered oxidative stress and preventing the disruption of Fe- and Zn-ion homeostasis and reduced glutathione and partially restored mitochondrial membrane potential. Moreover, Zn reduced the intracellular level of Cd to prevent the replacement by Cd of elements required for antioxidant enzyme activity and to protect protein sulphydryl groups against oxidation by free radicals. Further, Zn inhibited the synthesis alterations of Cd-induced ribosomal proteins, S-containing amino acids, S-rich proteins and antioxidant enzymes. Conversely, the investigation results of our study on the yeast model revealed that the Cd-treated protective effects of Zn on Cd-induced toxicity might be partially protective.

RNA-Seq identifies redox balance related gene expression alterations under acute cadmium exposure in yeast.

The nonessential metal cadmium can cause cell toxicity and is associated with a range of human diseases including cardiovascular diseases, neurodegenerative diseases and cancers. In this study, cadmium-induced global gene expression profile of yeast was obtained using RNA Sequencing (RNA-Seq) and further analyzed by means of informatics and experiments. A total of 912 Differentially Expressed Genes (DEGs) (FDR of q < 0.01), including 415 Cd-inducible and 497 Cd-repressed genes were identified. Based on the DEGs, 25 cadmium responsive Clusters of Orthologous Group (COG) and three types of cadmium-induced Gene Ontology (GO) including cellular components, molecular functions and biological processes were analyzed in details. Thereafter, 79 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways under cadmium exposure were assigned. Collectively, 108 redox balance related genes were extracted under cadmium exposure. Meanwhile, cadmium exposure lowered cellular Mitochondrial Membrane Potential (MMP) and increased Reactive Oxygen Species (ROS) levels significantly in the context of mitochondrial dysfunction. Furthermore, cadmium exposure increased cellular GSH levels and decreased GSSG levels and also lowered GSSG/GSH ratio of cells, which supports experimentally our claim that the redox balance is the primary mechanism for cadmium toxicity. The results present in this study may provide new strategies for cadmium detoxification and prevention or therapies of cadmium-associated diseases.