Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide with limited therapeutic options. HCC-induced immunosuppression often leads to ineffectiveness of immuno-promoting therapies. Currently, suppressing the suppressors has become the potential strategy for cancer immunotherapy. So, figuring out the immunosuppressive mechanisms induced and employed by HCC will be helpful to the design and application of HCC immunotherapy. Here, we identified one new subset of human CD14+CTLA-4+ regulatory dendritic cells (CD14+DCs) in HCC patients, representing ˜13% of peripheral blood mononuclear cells. CD14+DCs significantly suppress T-cell response in vitro through interleukin (IL)-10 and indoleamine-2,3-dioxygenase (IDO). Unexpectedly, CD14+DCs expressed high levels of cytotoxic T-lymphocyte antigen-4 (CTLA-4) and programmed death-1, and CTLA-4 was found to be essential to IL-10 and IDO production. So, we identified a novel human tumor-induced regulatory DC subset, which suppresses antitumor immune response through CTLA-4-dependent IL-10 and IDO production, thus indicating the important role of nonregulatory T-cell-derived CTLA-4 in tumor-immune escape or immunosuppression. Conclusions : These data outline one mechanism for HCC to induce systemic immunosuppression by expanding CD14+DCs, which may contribute to HCC progression. This adds new insight to the mechanism for HCC-induced immunosuppression and may also provide a previously unrecognized target of immunotherapy for HCC. (Hepatology 2014;59:567–579)

Adoptive transfer of chimeric antigen receptor (CAR)-modified natural killer (NK) cells represents a transformative approach that has significantly advanced clinical outcomes in patients with malignant hematological conditions. However, the efficacy of CAR-NK cells in treating solid tumors is limited by their exhaustion, impaired infiltration and poor persistence in the immunosuppressive tumor microenvironment (TME). As NK cell functional states are associated with IL-2 cascade, we engineered mesothelin-specific CAR-NK cells that secrete neoleukin-2/15 (Neo-2/15), an IL-2Rβγ agonist, to resist immunosuppressive polarization within TME. The adoptively transferred Neo-2/15-armored CAR-NK cells exhibited enhanced cytotoxicity, less exhaustion and longer persistence within TME, thereby having superior antitumor activity against pancreatic cancer and ovarian cancer. Mechanistically, Neo-2/15 provided sustained and enhanced downstream IL-2 receptor signaling, which promotes the expression of c-Myc and nuclear respiratory factor 1 (NRF1) in CAR-NK cells. This upregulation was crucial for maintaining mitochondrial adaptability and metabolic resilience, ultimately leading to increased cytotoxicity and pronounced persistence of CAR-NK cells within the TME. The resistance against TME immunosuppressive polarization necessitated the upregulation of NRF1, which is essential to the augmentative effects elicited by Neo-2/15. Overexpression of NRF1 significantly bolsters the antitumor efficacy of CAR-NK cells both in vitro and in vivo, with increased ATP production. Collectively, Neo-2/15-expressing CAR-NK cells exerts superior antitumor effects by exhaustion-resistance and longer survival in solid tumors.

As a common gastrointestinal tumor, the incidence of pancreatic cancer has been increasing in recent years. The disease shows multi-gene, multi-step complex evolution from occurrence to dissemination. Furthermore, pancreatic cancer has an insidious onset and an extremely poor prognosis, so it is difficult to obtain cinical specimens at different stages of the disease, and it is, therefore, difficult to observe tumorigenesis and tumor development in patients with pancreatic cancer. At present, no standard protocols stipulate clinical treatment of pancreatic cancer, and the benefit rate of new targeted therapies is low. For this reason, a well-established preclinical model of pancreatic cancer must be established to allow further exploration of the occurrence, development, invasion, and metastasis mechanism of pancreatic cancer, as well as to facilitate research into new therapeutic targets. A large number of animal models of pancreatic cancer are currently available, including a cancer cell line-based xenograft, a patient-derived xenograft, several mouse models (including transgenic mice), and organoid models. These models have their own characteristics, but they still cannot perfectly predict the clinical outcome of the new treatment. In this paper, we present the distinctive features of the currently popular pancreatic cancer models, and discuss their preparation methods, clinical relations, scientific purposes and limitations.

For decades, tumor-bearing murine models established using tumor cell lines have been the most commonly used models to study human cancers. Even though there are several studies reported that implant sites caused disparities in tumor behaviors, few of them illuminated the positional effect on immunotherapy. Herein, we describe surgical techniques for a novel orthotopic implantation of syngeneic pancreatic ductal adenocarcinoma (PDAC) tissue slices. This method has a high success modeling rate and stable growth kinetics, which makes it useful for testing novel therapeutics. Pathological examination indicated that the orthotopic tumor displayed poor vascularization, desmoplastic stromal reaction, and a highly immunosuppressive tumor microenvironment. This unique microenvironment resulted in limited response to PD1/CTLA4 blockade therapy and anti-MUC1 (αMUC1) CAR-T transfer treatment. To reverse the suppressive tumor microenvironment, we developed gene modified T-cells bearing a chimeric receptor in which activating receptor NKG2D fused to intracellular domains of 4-1BB and CD3ζ (NKG2D CAR). The NKG2D CAR-T cells target myeloid-derived suppressor cells (MDSCs), which overexpress Rae1 (NKG2D ligands) within the TME. Results indicated that NKG2D CAR-T cells eliminated MDSCs and improved antitumor activity of subsequently infused CAR-T cells. Moreover, we generated a bicistronic CAR-T, including αMUC1 CAR and NKG2D CAR separated by a P2A element. Treatment with the dual targeted bicistronic CAR-T cells also resulted in prolonged survival of orthotopic model mice. In summary, this study describes construction of a novel orthotopic PDAC model through implantation of tissue slices and discusses resistance to immunotherapy from the perspective of a PDAC microenvironment. Based on the obtained results, it is evident that elimination MDSCs by NKG2D CAR could rescue the impaired CAR-T cell activity.

Regulatory T cells can restrict the uncontrolled immune response and inflammation, avoiding pathologic immune injury to the host and thus playing important roles in the maintenance of immune homeostasis. Until recently, many subsets of CD4 and CD8 regulatory T cells have been reported. In this study, we identified CD11c^highCD8⁺ T cells as a new subset of CD8⁺ regulatory T cells. During Listeria monocytogenes and Staphylococcus aureus infection, two subsets of CD8 T cells were classified according to the expression level of CD11c, including CD11c^lowCD8⁺ and CD11c^highCD8⁺ T cells. CD11c^lowCD8⁺ T cells, existing during the whole period of infection, act as conventional activated T cells to kill target cells in a perforin-dependent manner. Interestingly, CD11c^highCD8⁺ T cells appeared only at a late stage of infection, expressed relatively high CD122 and low CD69, did not secrete IFN-γ, IL-10, TGF-β, and exhibited much more potent cytotoxicity against target cells via Fas ligand–Fas pathway in an Ag-independent manner. Ligation of CD11c was important in the cytotoxicity of CD11c^highCD8⁺ T cells. Furthermore, CD11c^highCD8⁺ T cells could directly kill the activated CD4 T cells both in vitro and in vivo, whereas CD11c^lowCD8⁺ T cells could not. Thus, we identified an infection-induced new subset of CD11c^highCD8⁺ regulatory T cells, which might contribute to protect host from pathological immune injure. Our results indicate that CD11c⁺CD8⁺ T cells are constitute a heterogeneous population that can be divided further into regulatory CD11c^highCD8⁺ T cell subset and effector CD11c^lowCD8⁺ T cell subset, thus adding insight to the role of CD8 T cells in immune response and regulation.