One of the primary goals in tumor immunotherapy is to reset the immune system from tolerogenic to immunogenic – a process in which invariant natural killer T (iNKT) cells are implicated. iNKT cells ...develop in the thymus and perform immunosurveillance against tumor cells peripherally. When optimally stimulated, iNKT cells differentiate and display more efficient immune functions. Some cells survive and act as effector memory cells. We discuss the putative roles of iNKT cells in antitumor immunity, and posit that it may be possible to develop novel therapeutic strategies to treat cancers using iNKT cells. In particular, we highlight the challenge of uniquely energizing iNKT cell-licensed dendritic cells to serve as effective immunoadjuvants for both arms of the immune system, thus coupling immunological networks.
iNKT cell subsets differentiate in the thymus, and iNKT1 cells can play a role in immune surveillance against cancer.Once optimally activated, iNKT1 cells can exert antitumor effects in peripheral tissues.Following activation, memory iNKT cells can differentiate in peripheral organs.Strategies using iNKT cell-licensed dendritic cells may constitute a promising new tool for immune enhancement in cancer immunotherapies.
CCL5 is a unique chemokine with distinct stage and cell-type specificities for regulating inflammation, but how these specificities are achieved and how CCL5 modulates immune responses is not well ...understood. Here we identify two stage-specific enhancers: the proximal enhancer mediates the constitutive CCL5 expression during the steady state, while the distal enhancer located 1.35 Mb from the promoter induces CCL5 expression in activated cells. Both enhancers are antagonized by RUNX/CBFβ complexes, and SATB1 further mediates the long-distance interaction of the distal enhancer with the promoter. Deletion of the proximal enhancer decreases CCL5 expression and augments the cytotoxic activity of tissue-resident T and NK cells, which coincides with reduced melanoma metastasis in mouse models. By contrast, increased CCL5 expression resulting from RUNX3 mutation is associated with more tumor metastasis in the lung. Collectively, our results suggest that RUNX3-mediated CCL5 repression is critical for modulating anti-tumor immunity.
Abstract
Most tumors employ multiple strategies to attenuate T-cell-mediated immune responses. In particular, immune suppression surrounding the tumor is achieved by interfering with ...antigen-presenting cells and effector T cells. Controlling both the tumor and the tumor microenvironment (TME) is critical for cancer treatment. Checkpoint blockade therapy can overcome tumor-induced immune suppression, but more than half of the patients fail to respond to this treatment; therefore, more effective cancer immunotherapies are needed. Generation of an anti-tumor immune response is a multi-step process of immune activation against the tumor that requires effector T cells to recognize and exert toxic effects against tumor cells, for which two strategies are employed—inhibition of various types of immune suppressor cells, such as myeloid cells and regulatory T cells, and establishment of anti-tumor immune surveillance including, activation of natural killer cells and cytotoxic T cells. It was recently shown that anti-cancer drugs not only directly kill tumor cells, but also influence the immune response to cancer by promoting immunogenic cell death, enhancing antigen presentation or depleting immunosuppressive cells. Herein, we review the mechanisms by which tumors exert immune suppression as well as their regulation. We then discuss how the complex reciprocal interactions between immunosuppressive and immunostimulatory cells influence immune cell dynamics in the TME. Finally, we highlight the new therapies that can reverse immune suppression in the TME and promote anti-tumor immunity.
Suppressive networks of immune cells in anti-tumor responses
The efficacy of current coronavirus disease 2019 (COVID‐19) vaccines has been demonstrated; however, emerging evidence suggests insufficient protection in certain immunocompromised cancer patients. ...We previously developed a cell‐based anti‐cancer vaccine platform involving artificial adjuvant vector cells (aAVCs) capable of inducing a strong adaptive response by enhancing the innate immunity. aAVCs are target antigen‐transfected allogenic cells that simultaneously express the natural killer T‐cell ligand–CD1d complex on their surface. In the present study, we applied this system for targeting the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) spike protein (CoV‐2‐S) using CoV‐2‐S‐expressing aAVCs (aAVC‐CoV‐2) and evaluated the immune response in a murine model. A single dose of aAVC‐CoV‐2 induced a large amount of CoV‐2‐S‐specific, multifunctional CTLs in addition to CD4+ T‐cell‐dependent anti‐CoV‐2‐S‐specific Abs. CoV‐2‐S‐specific CTLs infiltrated the lung parenchyma and persisted as long‐term memory T cells. Furthermore, we immunized mice with CoV‐2‐S‐ and tumor‐associated antigen (TAA)‐co‐expressing aAVCs (aAVC‐TAA/CoV‐2) and evaluated whether the anti‐SARS‐CoV‐2 and antitumor CTLs were elicited. We found that the aAVC‐TAA/CoV‐2‐S therapy exerted apparent antitumor effects and induced CoV‐2‐S‐specific CTLs. These findings suggest aAVC‐TAA/CoV‐2‐S therapy as a promising vaccine candidate for preventing COVID‐19, as well as enhancing the effectiveness of cancer therapies.
Due to the insufficient efficacy of current COVID‐19 vaccines in cancer patients, such high‐risk groups require more efficient vaccines that induce a strong memory response and provide dual protection against cancer and COVID‐19. We showed that SARS‐CoV‐2 spike protein‐expressing artificial adjuvant vector cells (aAVC‐CoV‐2) elicited the production of robust and long‐lived spike protein‐specific multifunctional cytotoxic T lymphocytes (CTLs) capable of infiltrating the lung parenchyma, thus illustrating the distinct advantage of using aAVC‐CoV‐2 as a second‐line vaccine, especially for individuals who are resistant to the current COVID‐19 vaccines. In addition, aAVCs expressing tumor‐associated antigen (TAA) and spike protein caused a dual induction of TAA‐specific CD8+ T cells and spike protein‐specific CD8+ T cells and provided sufficient protection against tumors, suggesting an effective strategy for treating cancer patients while simultaneously preventing SARS‐CoV‐2 infection.
The clinical benefits of immune checkpoint blockage (ICB) therapy have been widely reported. In patients with cancer, researchers have demonstrated the clinical potential of antitumor cytotoxic T ...cells that can be reinvigorated or enhanced by ICB. Compared to self-antigens, neoantigens derived from tumor somatic mutations are believed to be ideal immune targets in tumors. Candidate tumor neoantigens can be identified through immunogenomic or immunopeptidomic approaches. Identification of neoantigens has revealed several points of the clinical relevance. For instance, tumor mutation burden (TMB) may be an indicator of immunotherapy. In various cancers, mutation rates accompanying neoantigen loads may be indicative of immunotherapy. Furthermore, mismatch repair-deficient tumors can be eradicated by T cells in ICB treatment. Hence, immunotherapies using vaccines or adoptive T-cell transfer targeting neoantigens are potential innovative strategies. However, significant efforts are required to identify the optimal epitopes. In this review, we summarize the recent progress in the identification of neoantigens and discussed preclinical and clinical studies based on neoantigens. We also discuss the issues remaining to be addressed before clinical applications of these new therapeutic strategies can be materialized.
NY‐ESO‐1 is a cancer/testis antigen expressed in various cancer types. However, the induction of NY‐ESO‐1‐specific CTLs through vaccines is somewhat difficult. Thus, we developed a new type of ...artificial adjuvant vector cell (aAVC‐NY‐ESO‐1) expressing a CD1d‐NKT cell ligand complex and a tumor‐associated antigen, NY‐ESO‐1. First, we determined the activation of invariant natural killer T (iNKT) and natural killer (NK) cell responses by aAVC‐NY‐ESO‐1. We then showed that the NY‐ESO‐1‐specific CTL response was successfully elicited through aAVC‐NY‐ESO‐1 therapy. After injection of aAVC‐NY‐ESO‐1, we found that dendritic cells (DCs) in situ expressed high levels of costimulatory molecules and produced interleukn‐12 (IL‐12), indicating that DCs undergo maturation in vivo. Furthermore, the NY‐ESO‐1 antigen from aAVC‐NY‐ESO‐1 was delivered to the DCs in vivo, and it was presented on MHC class I molecules. The cross‐presentation of the NY‐ESO‐1 antigen was absent in conventional DC‐deficient mice, suggesting a host DC‐mediated CTL response. Thus, this strategy helps generate sufficient CD8+ NY‐ESO‐1‐specific CTLs along with iNKT and NK cell activation, resulting in a strong antitumor effect. Furthermore, we established a human DC‐transferred NOD/Shi‐scid/IL‐2γcnull immunodeficient mouse model and showed that the NY‐ESO‐1 antigen from aAVC‐NY‐ESO‐1 was cross‐presented to antigen‐specific CTLs through human DCs. Taken together, these data suggest that aAVC‐NY‐ESO‐1 has potential for harnessing innate and adaptive immunity against NY‐ESO‐1‐expressing malignancies.
In this study, we developed a new type of artificial adjuvant vector cell (aAVC‐NY‐ESO‐1) expressing a CD1d‐NKT cell ligand complex and a tumor‐associated antigen, NY‐ESO‐1. Although the induction of CTLs by vaccines for NY‐ESO‐1 is believed to be difficult, we successfully showed the NY‐ESO‐1‐specific CTLs by aAVC‐NY‐ESO‐1 therapy. As a key mechanism, we also determined that the NY‐ESO‐1 antigen from aAVC‐NY‐ESO‐1 was delivered to the DCs in situ.
The generation of tumor-directed cytotoxic T lymphocytes is considered crucial for the induction of antitumor immunity. To activate these CD8+ T cells, antigen-presenting cells (APCs) must initially ...acquire tumor cell-associated antigens. The major source of tumor antigens is dead tumor cells, but little is known about how APCs in draining lymph nodes acquire and crosspresent these antigens. Here we show that CD169+ macrophages phagocytose dead tumor cells transported via lymphatic flow and subsequently crosspresent tumor antigens to CD8+ T cells. Subcutaneous immunization with irradiated tumor cells protects mice from syngenic tumor. However, tumor antigen-specific CD8+ T cell activation and subsequent antitumor immunity are severely impaired in mice depleted with CD169+ macrophages. Neither migratory dendritic cells (DCs) nor lymph node-resident conventional DCs are essential for the crosspresentation of tumor antigens. Thus, we have identified CD169+ macrophages as lymph node-resident APCs dominating early activation of tumor antigen-specific CD8+ T cells.
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► Dead tumor cells in periphery accumulate in the draining lymph node sinus ► CD169+ macrophages phagocytose and crosspresent dead cell-associated antigens ► CD169+ macrophage-depleted mice fail to crossprime tumor-specific CD8 T cells ► CD169+ macrophages link tumor cell death and induction of antitumor immunity
Cancer is categorized into two types based on the microenvironment: cold and hot tumors. The former is challenging to stimulate through immunity. The immunogenicity of cancer relies on the quality ...and quantity of cancer antigens, whether recognized by T cells or not. Successful cancer immunotherapy hinges on the cancer cell type, antigenicity and subsequent immune reactions. The T cell response is particularly crucial for secondary epitope spreading, although the factors affecting these mechanisms remain unknown. Prostate cancer often becomes resistant to standard therapy despite identifying several antigens, placing it among immunologically cold tumors. We aim to leverage prostate cancer antigens to investigate the potential induction of epitope spreading in cold tumors. This study specifically focuses on identifying factors involved in secondary epitope spreading based on artificial adjuvant vector cell (aAVC) therapy, a method established as invariant natural killer T (iNKT) -licensed DC therapy.
We concentrated on three prostate cancer antigens (prostate-specific membrane antigen (PSMA), prostate-specific antigen (PSA), and prostatic acid phosphatase (PAP)). By introducing allogeneic cells with the antigen and murine CD1d mRNA, followed by α-galactosylceramide (α-GalCer) loading, we generated five types of aAVCs, i.e, monovalent, divalent and trivalent antigen-expressing aAVCs and four types of prostate antigen-expressing cold tumors. We evaluated iNKT activation and antigen-specific CD8+ T cell responses against tumor cells prompted by the aAVCs.
Our study revealed that monovalent aAVCs, expressing a single prostate antigen, primed T cells for primary tumor antigens and also induced T cells targeting additional tumor antigens by triggering a tumor antigen-spreading response. When we investigated the immune response by trivalent aAVC (aAVC-PROS), aAVC-PROS therapy elicited multiple antigen-specific CD8+ T cells simultaneously. These CD8+ T cells exhibited both preventive and therapeutic effects against tumor progression.
The findings from this study highlight the promising role of tumor antigen-expressing aAVCs, in inducing efficient epitope spreading and generating robust immune responses against cancer. Our results also propose that multivalent antigen-expressing aAVCs present a promising therapeutic option and could be a more comprehensive therapy for treating cold tumors like prostate cancer.
(K0.5Na0.5)NbO3 (KNN) + x (= 1, 0.5, 0.05, and 0) wt%Co3O4 single crystals were fabricated by a solid-state crystal growth method with a KTaO3 seed crystal and a KNN atmosphere powder, and the ...effects of the sintering aid content x and the addition of Co3O4 to the atmosphere powder on the growth of the single crystals were investigated. The formation of pores in the single crystals was suppressed by a decrease of x, which, however, decreased the crystal growth length. On the other hand, dense and large KNN single crystals could be fabricated by sintering with a KNN + 5 wt%Co3O4 atmosphere at x = 0. The dielectric, ferroelectric, and piezoelectric properties of the KNN single crystals were comparable to those of reported (K,Na)NbO3 single crystals. These results would be useful for fabricating dense and large single crystals by the solid-state crystal growth method.
Abstract
Influenza viruses are a major public health problem. Vaccines are the best available countermeasure to induce effective immunity against infection with seasonal influenza viruses; however, ...the breadth of antibody responses in infection versus vaccination is quite different. Here, we show that nasal infection controls two sequential processes to induce neutralizing IgG antibodies recognizing the hemagglutinin (HA) of heterotypic strains. The first is viral replication in the lung, which facilitates exposure of shared epitopes that are otherwise hidden from the immune system. The second process is the germinal center (GC) response, in particular, IL-4 derived from follicular helper T cells has an essential role in the expansion of rare GC-B cells recognizing the shared epitopes. Therefore, the combination of exposure of the shared epitopes and efficient proliferation of GC-B cells is critical for generating broadly-protective antibodies. These observations provide insight into mechanisms promoting broad protection from virus infection.
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