Identification of a new HLA-A*0201-restricted cytotoxic T lymphocyte epitope from TC2N

Identification of cytotoxic T lymphocyte (CTL) epitopes from tumor related antigens is a promising approach for malignant tumor immunotherapy. TC2N, a recently identified tumor associated antigen from human glioblastoma, is regarded as a promising target of tumor-specific immunotherapy. As one of the most widely used histocompatibility molecules in Chinese is HLA-A*0201, we were able to identify the TC2N peptides that are provided by this molecular type. A panel of antigenic peptides produced from TC2N were predicted by using a computer tool. The binding affinities of three peptides with the highest predicted score to the HLA-A*0201 molecule were evaluated after synthesis. In vitro and in vivo stimulation of the main T-cell response against the predicted peptides. The results demonstrated that TC2N (152-160) was able to release IFN-γ and lyse U251 cells in vitro as well as in vivo by eliciting peptide-specific CTLs. Our results indicated that peptide TC2N (152-160) (RLYGSVCDL) was a novel HLA-A2.1-restricted CTL epitope capable of inducing TC2N specific CTLs in vitro. As TC2N might qualify as a viable target for immunotherapeutic approaches for patients with GBM, we speculated that the newly identified epitope RLYGSVCDL would be of potential use in peptide-based, cancer-specific immunotherapy against GBM.

NF9 peptide specific cytotoxic T lymphocyte clone cross react to Y453F mutation of SARS-CoV-2 virus spike protein

The recognition by cytotoxic T cells (CTLs) is essential for the clearance of SARS-CoV-2 virus-infected cells. Several viral proteins have been described to be recognized by CTLs. Among them, the spike (S) protein is one of the immunogenic proteins. The S protein acts as a ligand for its receptors, and several mutants with different affinities for its cognate receptors have been reported, and certain mutations in the S protein, such as L452R and Y453F, have been found to inhibit the HLA-A24-restricted CTL response. In this study, we conducted a screening of candidate peptides derived from the S protein, specifically targeting those carrying the HLA-A24 binding motif. Among these peptides, we discovered that NF9 (NYNYLYRLF) represents an immunogenic epitope. CTL clones specific to the NF9 peptide were successfully established. These CTL clones exhibited the ability to recognize endogenously expressed NF9 peptide. Interestingly, the CTL clone demonstrated cross-reactivity with the Y453F peptide (NYNYLFRLF) but not with the L452R peptide (NYNYRYRLF). The CTL clone was able to identify the endogenously expressed Y453F mutant peptide. These findings imply that the NF9-specific CTL clone possesses the capability to recognize and respond to the Y453F mutant peptide.

Advancements in Cell-Based Therapies for HIV Cure

The treatment of human immunodeficiency virus (HIV-1) has evolved since the establishment of combination antiretroviral therapy (ART) in the 1990s, providing HIV-infected individuals with approaches that suppress viral replication, prevent acquired immunodeficiency syndrome (AIDS) throughout their lifetime with continuous therapy, and halt HIV transmission. However, despite the success of these regimens, the global HIV epidemic persists, prompting a comprehensive exploration of potential strategies for an HIV cure. Here, we offer a consolidated overview of cell-based therapies for HIV-1, focusing on CAR-T cell approaches, gene editing, and immune modulation. Persistent challenges, including CAR-T cell susceptibility to HIV infection, stability, and viral reservoir control, underscore the need for continued research. This review synthesizes current knowledge, highlighting the potential of cellular therapies to address persistent challenges in the pursuit of an HIV cure.

Mini-TCRs: Truncated T cell receptors to generate T cells from induced pluripotent stem cells

Allogeneic T cell platforms utilizing induced pluripotent stem cell (iPSC) technology exhibit significant promise for the facilitation of adoptive immunotherapies. While mature T cell receptor (TCR) signaling plays a crucial role in generating T cells from iPSCs, the introduction of exogenous mature TCR genes carries a potential risk of causing graft-versus-host disease (GvHD). In this study, we present the development of truncated TCRα and TCRβ chains, termed mini-TCRs, which lack variable domains responsible for recognizing human leukocyte antigen (HLA)-peptide complexes. We successfully induced cytotoxic T lymphocytes (CTLs) from iPSCs by employing mini-TCRs. Combinations of TCRα and TCRβ fragments were screened from mini-TCR libraries based on the surface localization of CD3 proteins and their ability to transduce T cell signaling. Consequently, mini-TCR-expressing iPSCs underwent physiological T cell development, progressing from the CD4 and CD8 double-positive stage to the CD8 single-positive stage. The resulting iPSC-derived CTLs exhibited comparable cytokine production and cytotoxicity in comparison to that of full-length TCR-expressing T lymphocytes when chimeric antigen receptors (CARs) were expressed. These findings demonstrate the potential of mini-TCR-carrying iPSCs as a versatile platform for CAR T cell therapy, offering a promising avenue for advancing adoptive immunotherapies.

T-lymphocytes from focused ultrasound ablation subsequently mediate cellular antitumor immunity after adoptive cell transfer immunotherapy

Background

Our previous studies found that high-intensity focused ultrasound (HIFU) stimulated tumor-specific T cells in a mouse H22 tumor model, and adoptive transfer of the T cells from HIFU-treated mice could subsequently elicit stronger inhibition on the growth and progression of the implanted tumors. The aim of this study was to investigate the mechanism of T cells from focused ultrasound ablation in HIFU-mediated immunomodulation.

Methods

Sixty H22 tumor-bearing mice were treated by either HIFU or sham-HIFU, and 30 naïve syngeneic mice served as controls. All mice were euthanized on day 14 after HIFU and splenic T cell suspensions were obtained in each group. Using an adoptive cell transfer model, a total of 1 × 106 T cells from HIFU treated-mice were intravenously injected into each syngeneic H22 tumor-bearing mouse twice on day 3 and 4, followed by the sacrifice for immunological assessments at 14 days after the adoptive transfer.

Results

T cells from HIFU-treated mice could significantly enhance the cytotoxicity of CTLs (p < 0.001), with a significant increase of TNF-α (p < 0.001) and IFN-γ secretion (p < 0.001). Compared to control and sham-HIFU groups, the number of Fas ligand+ and perforin+ tumor-infiltrating lymphocytes (TILs) and apoptotic H22 tumor cells were significantly higher (p < 0.001) in the HIFU group. There were linear correlations between apoptotic tumor cells and Fas ligand+ TILs (r = 0.9145, p < 0.001) and perforin+ TILs (r = 0.9619, p < 0.001).

Conclusion

T cells from HIFU-treated mice can subsequently mediate cellular antitumor immunity, which may play an important role in the HIFU-based immunomodulation.

Lower Circulating Cytotoxic T-Cell Frequency and Higher Intragraft Granzyme-B Expression Are Associated with Inflammatory Interstitial Fibrosis and Tubular Atrophy in Renal Allograft Recipients

Background and Objectives: Inflammatory interstitial fibrosis and tubular atrophy (i-IFTA) is an inflammation in the area of tubular atrophy and fibrosis. i-IFTA is poorly associated with graft outcome and associated with infiltration of inflammatory mononuclear cells. A cytotoxic T cell is a granzyme B⁺CD8⁺CD3⁺ T cell, mainly secret granzyme B. Granzyme B is a serine protease that may mediate allograft injury and inflammatory interstitial fibrosis and tubular atrophy (i-IFTA). However, there is no report identifying the association of granzyme B with i-IFTA after a long post-transplant interval. Material and Methods: In this study, we have measured the cytotoxic T-cell frequency with flow cytometry, serum and PBMCs culture supernatants granzyme-B levels with ELISA and intragraft granzyme-B mRNA transcript expression with the RT-PCR in RTRs in 30 patients with biopsy-proven i-IFTA and 10 patients with stable graft function. Result: The frequency of cytotoxic T cells (CD3⁺CD8⁺ granzyme B⁺) in SGF vs. i-IFTA was (27.96 ± 4.86 vs. 23.19 ± 3.85%, p = 0.011), the serum granzyme-B level was (100.82 ± 22.41 vs. 130.32 ± 46.60, p = 0.038 pg/mL) and the intragraft granzyme-B mRNA transcript expression was (1.01 ± 0.048 vs. 2.10 ± 1.02, p < 0.001 fold). The frequency of CD3⁺ T cells in SGF vs. i-IFTA was (66.08 ± 6.8 vs. 65.18 ± 9.35%; p = 0.68) and that of CD3⁺CD8⁺ T cells was (37.29 ± 4.11 vs. 34.68 ± 5.43%; p = 0.28), which were similar between the 2 groups. CTLc frequency was negatively correlated with urine proteinuria (r = -0.51, p < 0.001), serum creatinine (r = -0.28, p = 0.007) and eGFR (r = -0.28, p = 0.037). Similarly, the PBMC culture supernatants granzyme-B level was negatively correlated with urine proteinuria (r = -0.37, p < 0.001) and serum creatinine (r = -0.31, p = 0.002), while the serum granzyme-B level (r = 0.343, p = 0.001) and intragraft granzyme-B mRNA transcript expression (r = 0.38, p < 0.001) were positively correlated with proteinuria. Conclusions: A decrease in the CTLc frequency in circulation and an increased serum granzyme-B level and intragraft granzyme-B mRNA expression shows that cytotoxic T cells may mediate the allograft injury in RTRs with i-IFTA by releasing granzyme B in serum and intragraft tissue.

Simultaneous targeting of PD-1 and IL-2Rβγ with radiation therapy inhibits pancreatic cancer growth and metastasis

In pancreatic ductal adenocarcinoma (PDAC) patients, we show that response to radiation therapy (RT) is characterized by increased IL-2Rβ and IL-2Rγ along with decreased IL-2Rα expression. The bispecific PD1-IL2v is a PD-1-targeted IL-2 variant (IL-2v) immunocytokine with engineered IL-2 cis targeted to PD-1 and abolished IL-2Rα binding, which enhances tumor-antigen-specific T cell activation while reducing regulatory T cell (Treg) suppression. Using PD1-IL2v in orthotopic PDAC KPC-driven tumor models, we show marked improvement in local and metastatic survival, along with a profound increase in tumor-infiltrating CD8+ T cell subsets with a transcriptionally and metabolically active phenotype and preferential activation of antigen-specific CD8+ T cells. In combination with single-dose RT, PD1-IL2v treatment results in a robust, durable expansion of polyfunctional CD8+ T cells, T cell stemness, tumor-specific memory immune response, natural killer (NK) cell activation, and decreased Tregs. These data show that PD1-IL2v leads to profound local and distant response in PDAC.

Recombinant Human Cyclophilin A in Combination with Adoptive T-cell Therapy Improves the Efficacy of Cancer Immunotherapy in Experimental Models in vivo

Adoptive T-cell therapy (ACT) is successfully applied in cancer treatment; however, its efficiency can be limited by a low viability, short persistence time, and loss of functional activity of T-cells after adoptive transfer. The search for novel immunomodulators that can improve the viability, expansion, and functions of T-cells after their infusion with the minimal side effects could contribute to the development of more efficient and safe ACT strategies. Recombinant human cyclophilin A (rhCypA) is of particular interest in this respect, as it exhibits pleiotropic immunomodulatory activity and stimulates both innate and adaptive anti-tumor immunity. Here, we evaluated the effect of rhCypA on the efficacy of ACT in the mouse EL4 lymphoma model. Lymphocytes from transgenic 1D1a mice with an inborn pool of EL4-specific T-cells were used as a source of tumor-specific T-cells for ACT. In models of immunocompetent and immunodeficient transgenic mice, the course (3 days) rhCypA administration was shown to significantly stimulate EL4 rejection and prolong the overall survival of tumor-bearing mice after adoptive transfer of lowered doses of transgenic 1D1a cells. Our studies showed that rhCypA significantly improved the efficacy of ACT by enhancing the effector functions of tumor-specific cytotoxic T-cells. These findings open up the prospects for the development of innovative strategies of adoptive T-cell immunotherapy for cancer using rhCypA as an alternative to existing cytokine therapies.

Developing Next-Generation Protein-Based Vaccines Using High-Affinity Glycan Ligand-Decorated Glyconanoparticles

Major diseases, such as cancer and COVID-19, are frightening global health problems, and sustained action is necessary to develop vaccines. Here, for the first time, ethoxy acetalated dextran nanoparticles (Ace-Dex-NPs) are functionalized with 9-N-(4H-thieno[3,2-c]chromene-2-carbamoyl)-Siaα2-3Galβ1-4GlcNAc (TCC Sia-LacNAc) targeting macrophages as a universal vaccine design platform. First, azide-containing oxidized Ace-Dex-NPs are synthesized. After the NPs are conjugated with ovalbumin (OVA) and resiquimod (Rd), they are coupled to TCC Sia-LacNAc-DBCO to produce TCC Sia-Ace-Dex-OVA-Rd, which induce a potent, long-lasting OVA-specific cytotoxic T-lymphocyte (CTL) response and high anti-OVA IgG, providing mice with superior protection against tumors. Next, this strategy is exploited to develop vaccines against infection by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). The receptor-binding domain (RBD) of the SARS-CoV-2 spike protein is the main target for neutralizing antibodies. The TCC Sia-Ace-Dex platform is preferentially used for designing an RBD-based vaccine. Strikingly, the synthetic TCC Sia-Ace-Dex-RBD-Rd elicited potent RBD-neutralizing antibodies against live SARS-CoV-2 infected Vero E6 cells. To develop a universal SARS-CoV-2 vaccine, the TCC Sia-Ace-Dex-N-Rd vaccine carrying SARS-CoV-2 nucleocapsid protein (N) is also prepared, which is highly conserved among SARS-CoV-2 and its variants of concern (VOCs), including Omicron (BA.1 to BA.5); this vaccine can trigger strong N-specific CTL responses against target cells infected with SARS-CoV-2 and its VOCs.

Overexpression of VEGF in the MOPC 315 Plasmacytoma Induces Tumor Immunity in Mice

Vascular endothelial growth factor (VEGF) has important effects on hematopoietic and immune cells. A link between VEGF expression, tumor progression, and metastasis has been established in various solid tumors; however, the impact of VEGF expression by hematopoietic neoplasias remains unclear. Here, we investigated the role of VEGF in plasma cell neoplasia. Overexpression of VEGF in MOPC 315 tumor cells (MOPCSVm) had no effect on their growth in vitro. However, constitutive ectopic expression of VEGF dramatically reduced tumorigenicity of MOPC 315 when implanted subcutaneously into BALB/c mice. Mice implanted with MOPCSVm effectively rejected tumor grafts and showed strong cytotoxic T lymphocyte (CTL) activity against parental MOPC 315 cells. MOPCSVm implants were not rejected in nude mice, suggesting the process is T-cell-dependent. Adoptive transfer of splenocytes from recipients inoculated with MOPCSVm cells conferred immunity to naïve BALB/c mice, and mice surviving inoculation with MOPCSVm rejected the parental MOPC 315 tumor cells following a second inoculation. Immunohistochemical analysis showed that MOPCSVm induced a massive infiltration of CD3+ cells and MHC class II+ cells in vivo. In addition, exogenous VEGF induced the expression of CCR3 in T cells in vitro. Together, these data are the first to demonstrate that overexpression of VEGF in plasmacytoma inhibits tumor growth and enhances T-cell-mediated antitumor immune response.

Restoring FAS Expression via Lipid-Encapsulated FAS DNA Nanoparticle Delivery Is Sufficient to Suppress Colon Tumor Growth In Vivo

Simple Summary

A key feature of human colorectal tumor is loss of FAS expression. FAS is the death receptor for FASL of activated T cells. Loss of FAS expression therefore may promote tumor cell immune escape. We aimed at determining whether restoring FAS expression is sufficient to suppress colorectal tumor growth. Mouse and human FAS cDNA was synthesized and encapsulated into cationic lipid nanoparticle DOTAP-Cholesterol to formulate DOTAP-Chol-mFAS and DOTAP-Chol-hFAS, respectively. Restoring FAS expression in metastatic mouse colon-tumor cells enabled FASL-induced elimination of FAS⁺ tumor cells in vitro and suppressed colon-tumor growth and progression in tumor-bearing mice in vivo. Restoring FAS expression induced FAS receptor auto-oligomerization and tumor cell auto-apoptosis in metastatic human colon-tumor cells in vitro. DOTAP-Chol-hFAS therapy is also sufficient to suppress metastatic human colon tumor xenograft growth in athymic mice. Tumor-selective delivery of FAS DNA nanoparticle is potentially an effective therapy for human colorectal cancer.

Abstract

A hallmark of human colorectal cancer is lost expression of FAS, the death receptor for FASL of cytotoxic T lymphocytes (CTLs). However, it is unknown whether restoring FAS expression alone is sufficient to suppress csolorectal-cancer development. The FAS promoter is hypermethylated and inversely correlated with FAS mRNA level in human colorectal carcinomas. Analysis of single-cell RNA-Seq datasets revealed that FAS is highly expressed in epithelial cells and immune cells but down-regulated in colon-tumor cells in human colorectal-cancer patients. Codon usage-optimized mouse and human FAS cDNA was designed, synthesized, and encapsulated into cationic lipid to formulate nanoparticle DOTAP-Chol-mFAS and DOTAP-Chol-hFAS, respectively. Overexpression of codon usage-optimized FAS in metastatic mouse colon-tumor cells enabled FASL-induced elimination of FAS⁺ tumor cells in vitro, suppressed colon tumor growth, and increased the survival of tumor-bearing mice in vivo. Overexpression of codon-optimized FAS-induced FAS receptor auto-oligomerization and tumor cell auto-apoptosis in metastatic human colon-tumor cells. DOTAP-Chol-hFAS therapy is also sufficient to suppress metastatic human colon tumor xenograft growth in athymic mice. DOTAP-Chol-mFAS therapy exhibited no significant liver toxicity. Our data determined that tumor-selective delivery of FAS DNA nanoparticles is sufficient for suppression of human colon tumor growth in vivo.

Steroid-resistant intestinal aGVHD and refractory CMV and EBV infections complicated by haplo-HSCT were successfully rescued by FMT and CTL infusion

Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) produces similar survival outcomes as HLA-matched sibling donor allogeneic HCST in younger patients with acquired severe aplastic anemia (SAA). This study reported a 29-years-old man with SAA and intracranial hemorrhage who underwent haplo-HSCT with a modified BU/CY + ATG conditioning regimen. Neutrophil and platelet engraftment were both achieved on day 14 after HSCT. The patient developed grade IV acute graft-versus-host disease (aGVHD) on day 20 and acquired cytomegalovirus (CMV) and Epstein-Barr virus (EBV) infections on day 47. After the failure of methylprednisolone, basiliximab, ruxolitinib, and antiviral treatment, the patient was diagnosed with steroid-resistant grade IV aGVHD and refractory CMV and EBV infections. We performed fecal microbiota transplantation and infused CMV- and EBV-specific cytotoxic T lymphocytes. After that the stool volume and frequency gradually decreased, and viral DNA was undetectable on day 80. This report provides helpful clinical experience for treating steroid-resistant aGVHD and refractory viral infections.

Upregulation of CD3ζ and L-selectin in antigen-specific cytotoxic T lymphocytes by eliminating myeloid-derived suppressor cells with doxorubicin to improve killing efficacy of neuroblastoma cells in vitro

Background

Agglomeration of myeloid‐derived suppressor cells (MDSCs) in tumors impedes immunotherapeutic effects. Doxorubicin (DOX) is currently the most specific drug used for the selective removal of MDSCs. Here, we study the feasibility and mechanism of eliminating MDSCs by DOX to improve antigen‐specific cytotoxic T lymphocyte (CTL)‐killing neuroblastoma (NB) cells in vitro.

Methods

CTL and MDSC were prepared; then, CTLs, NB cells, MDSCs, and DOX were mixed and cultivated in different collocation patterns and divided into different groups. The levels of cluster of differentiation 3ζ chain (CD3ζ) and L‐selectin in CTL in different groups were detected. Thereafter, the killing rate of NB cells and secretion of interleukin‐2 and interferon‐γ were measured and compared.

Results

By real‐time polymerase chain reaction (PCR) and Western blot test respectively, the proliferation and killing effect of CTLs on NB cells were all inhibited by MDSC through downregulating CD3ζ (p = 0.002; p = 0.001) and L‐selectin (p = 0.006; p < 0.001). However, this inhibitory effect was reversed by DOX. Significant differences were observed in the levels of interleukin‐2 (p < 0.001), interferon‐γ (p < 0.001), and the killing rate (p < 0.001) among the groups, except between the CTL +SK‐N‐SH and CTL +SK‐N‐SH +DOX groups (p > 0.05).

Conclusions

Targeted elimination of MDSCs by DOX can improve Ag‐specific CTL killing of NB cells in vitro by upregulating CD3ζ and L‐selectin. This study provides a novel method to enhance the immunotherapeutic effects of NB.

Alterations in Immune Response Profile of Tumor-Draining Lymph Nodes after High-Intensity Focused Ultrasound Ablation of Breast Cancer Patients

Previous studies have revealed that high-intensity focused ultrasound (HIFU) ablation can trigger an antitumor immune response. The aim of this study was to investigate immune response in tumor-draining lymph nodes (TDLNs) after HIFU treatment. Forty-eight female patients with biopsy-confirmed breast cancer were divided into a control group and an HIFU group. In the control group, 25 patients underwent modified radical mastectomy, but 23 patients in the HIFU group received HIFU ablation of primary cancer, followed by the same operation. Using HE and immunohistochemical staining, the immunologic reactivity pattern and immune cell profile were assessed in paraffin-embedded axillary lymph nodes (ALNs) in all patients. The results showed that ALNs presented more evident immune reactions in the HIFU group than in the control group (100% vs. 64%). Among the ALNs, 78.3% had mixed cellular and humoral immune response, whereas 36% in the control group showed cellular immune response. The numbers of CD3⁺, CD4⁺, NK cell, and activated CTLs with Fas ligand⁺, granzyme⁺ and perforin⁺ expression were significantly higher in the ALNs in the HIFU group. It was concluded that HIFU could stimulate potent immune response and significantly increase T cell, activated CTLs and NK cell populations in the TDLNs of breast cancer.

Myeloid dendritic cells in severe aplastic anemia patients exhibit stronger phagocytosis

BACKGROUND

A deeper understanding of the pathogenesis of severe aplastic anemia (SAA) is urgently warranted to achieve better therapeutic effects. The objective of this study was to investigate the phagocytosis of myeloid dendritic cell (mDC) in SAA patients.

METHODS

Myeloid dendritic cells were induced in vitro from bone marrow mononuclear cells from 26 SAA patients and 12 normal controls (HCs). The phagocytosis of mDCs was detected by flow cytometry using FITC-Dextran (40KD), and its correlation with the immune status and severity of the disease was analyzed.

RESULTS

The phagocytosis of mDC from untreated SAA patients was significantly stronger than that from complete remission group and HC group (p < 0.05). There was no statistical difference between the latter two groups (p > 0.05). The phagocytosis of mDC from SAA patients correlated positively with the concentration of interleukin (IL)-2 (r = 0.389, p < 0.05), and IL-4 (r = 0.556, p < 0.05), negatively with CD4⁺ /CD8⁺ ratio (r = -0.421, p < 0.05). It also had negative correlations with the level of hemoglobin (r = -0.393, p < 0.05), white blood cell (r = -0.436, p < 0.05), platelet (r = -0.431, p < 0.05), and reticulocyte (r = -0.447, p < 0.05). The phagocytosis of mDC does not correlate with the response to IST.

CONCLUSIONS

The increased phagocytosis of mDC in untreated SAA patients may contribute to abnormal activation of T helper (Th) and subsequent cytotoxic T lymphocyte (CTL) activation in these patients. It may be involved in the immune pathogenesis of SAA.

Nanocomplex-Mediated In Vivo Programming to Chimeric Antigen Receptor-M1 Macrophages for Cancer Therapy

Chimeric antigen receptor-T (CAR-T) cell immunotherapy has shown impressive clinical outcomes for hematologic malignancies. However, its broader applications are challenged due to its complex ex vivo cell-manufacturing procedures and low therapeutic efficacy against solid tumors. The limited therapeutic effects are partially due to limited CAR-T cell infiltration to solid tumors and inactivation of CAR-T cells by the immunosuppressive tumor microenvironment. Here, a facile approach is presented to in vivo program macrophages, which can intrinsically penetrate solid tumors, into CAR-M1 macrophages displaying enhanced cancer-directed phagocytosis and anti-tumor activity. In vivo injected nanocomplexes of macrophage-targeting nanocarriers and CAR-interferon-γ-encoding plasmid DNA induce CAR-M1 macrophages that are capable of CAR-mediated cancer phagocytosis, anti-tumor immunomodulation, and inhibition of solid tumor growth. Together, this study describes an off-the-shelf CAR-macrophage therapy that is effective for solid tumors and avoids the complex and costly processes of ex vivo CAR-cell manufacturing.

Transplantation of Graft Anti-Host Cytotoxic T Lymphocytes Along with Allogeneic Bone Marrow Skips Macrophage-Induced Graft-Versus-Host Disease

Graft-versus-host disease (GVHD) is a physiological response of the graft to allogeneic hosts. However, the effector cells, affected organ(s), and cytokines in the GVHD remain controversially discussed, without having determined a particular cytotoxic activity of the graft against the host. After i.v. injection of C57BL/6 (H-2^b) spleen cells into irradiated BDF1 (H-2^b/d) mice, the hosts developed interferon-gamma (IFN-γ)-dependent bone marrow (BM) GVHD on days 5-17. When H-2D^dK^d transgenic H-2^b lymphoma cells were i.p. inoculated into irradiated, H-2^b splenocyte-transplanted H-2^b/d mice, the infiltration of macrophages cytotoxic against H-2D^dK^d transgenic H-2^b mouse skin epithelia (a GVHD activity) into the peritoneal cavity preceded several days the infiltration of interleukin (IL)-2-dependent cytotoxic T lymphocytes (CTLs) to achieve a graft-versus-leukemia (GVL) effect. In contrast, allogeneic BM transplanted alone into the irradiated mice did not induce GVHD for 44 days, whereas i.v. injection of graft anti-host macrophages or graft anti-host CTLs along with allogeneic BM, respectively, induced GVHD or promoted the GVL effect in the absence of GVHD. These results revealed that macrophage-induced GVHD and the CTL-mediated GVL effect were a set (Th1: IFN-γ/IL-2) response of the graft to allogeneic hosts and leukemia cells, respectively, and that graft T cell activation rather than inhibition skipped GVHD after BM transplantation.

Enhanced CXCR4 Expression of Human CD8Low T Lymphocytes Is Driven by S1P4

Although the human immune response to cancer is naturally potent, it can be severely disrupted as a result of an immunosuppressive tumor microenvironment. Infiltrating regulatory T lymphocytes contribute to this immunosuppression by inhibiting proliferation of cytotoxic CD8⁺ T lymphocytes, which are key to an effective anti-cancer immune response. Other important contributory factors are thought to include metabolic stress caused by the local nutrient deprivation common to many solid tumors. Interleukin-33 (IL-33), an alarmin released in reaction to cell damage, and sphingosine-1-phosphate (S1P) are known to control cell positioning and differentiation of T lymphocytes. In an in vitro model of nutrient deprivation, we investigated the influence of IL-33 and S1P receptor 4 (S1P₄) on the differentiation and migration of human CD8⁺ T lymphocytes. Serum starvation of CD8⁺ T lymphocytes induced a subset of CD8^Low and IL-33 receptor-positive (ST2L⁺) cells characterized by enhanced expression of the regulatory T cell markers CD38 and CD39. Both S1P₁ and S1P₄ were transcriptionally regulated after stimulation with IL-33. Moreover, expression of the chemokine receptor CXCR4 was increased in CD8⁺ T lymphocytes treated with the selective S1P₄ receptor agonist CYM50308. We conclude that nutrient deprivation promotes CD8^Low T lymphocytes, contributing to an immunosuppressive microenvironment and a poor anti-cancer immune response by limiting cytotoxic effector functions. Our results suggest that S1P₄ signaling modulation may be a promising target for anti-CXCR4 cancer immunotherapy.

Immunity beyond cancer cells: perspective from tumor tissue

Investigation of cancer as a cell-level disease has led to the development of cancer cell-directed therapies including cytotoxic T lymphocyte (CTL)-based immunotherapy; yet, many patients are refractory to these modalities of cancer treatment and acquired resistance frequently occurs. Of note, cancer environment controls the manifestation of cancerous cell phenotype. Helper T (Th) cells orchestrate immune defense responses targeting cancer cells as well as the tumor microenvironment. Recent studies have shown that in addition to interferon (IFN)-γ-producing Th1 cells, interleukin (IL)-4-producing Th2 cells function as potent anticancer effectors in part by promoting tumor stroma reconfiguration and tumor tissue repair. Such Th cell-mediated tissue-level immunity may be harnessed for novel modalities of cancer environment immunotherapy.

Combined treatment with epigenetic agents enhances anti-tumor activity of T cells by upregulating the ACRBP expression in hepatocellular carcinoma

OBJECTIVE

To evaluate the efficacy of combined epigenetic drugs of decitabine (DAC), valproic acid (VPA) and trichostatin A (TSA) on immunotherapy with a murine model of hepatocellular carcinoma (HCC).

METHODS

Dendritic cells (DCs) transduced with recombinant lentivirus expressing a cancer-testis antigen, acrosin binding protein (ACRBP), are referred to as DC/ACRBP. CD8⁺ T cells were harvested from spleens of C57BL/6 mice and activated by DC/ACRBP. Cytotoxicity of DC/ACRBP-activated T cells was analyzed by cytotoxicity and murine xenograft assays.

RESULTS

Cytotoxicity assay results revealed that DC/ACRBP-activated T cells exhibited the highest cytotoxicity against HCC cells pre-treated with triple drugs (DAC+VPA+TSA) compared with dual drugs (DAC+VPA and DAC+TSA) and single drug (DAC, VPA and TSA) respectively. Analyses of RT-PCR and immunoblotting demonstrated that the highest ACRBP expression of HCC cells was induced by the triple drugs compared with the single and dual drugs. These results indicated that DC/ACRBP-activated T cells might be ACRBP-specific lymphocytes, and the augmented cytotoxicity may be dependent on the upregulation of ACRBP expression. These assumptions were further confirmed by xenograft tumor assay. Tumor cells of mice administrated with the triple drugs exhibited increased ACRBP expression compared with those of mice without administration. As expected, DC/ACRBP-activated T cells adopted by mice injected with the triple drugs, compared with those adopted by mice without injection, remarkably impeded growth and facilitated apoptosis of tumor cells.

CONCLUSION

These data suggested that combined treatment with DAC, VPA and TSA may enhance the anti-tumor efficacy of ACRBP-specific T cells by upregulating ACRBP expression in HCC.

Imbalance of T Lymphocyte Subsets in Adult Immune Thrombocytopenia

Background

Primary immune thrombocytopenia (ITP) is defined as an acquired autoimmune disease characterized by isolated thrombocytopenia. This work is to further clarify the relationship between T cell immune dysfunction and the pathogenesis of ITP.

Methods

37 adult patients with ITP were selected and were classified into newly diagnosed ITP (nITP, n = 13), persistent ITP (pITP, n = 6) and chronic ITP (cITP n = 18). The frequency of cytotoxic T lymphocytes (Tc1, Tc2, and Tc17) and helper T cells (Th1, Th2, and Th17), Tregs, and the expression of chemokine receptors and PD-1 on CD4⁺ T cells were investigated by flow cytometry. Plasma levels of T cell-related cytokines (IL-2, IL-4, IL-6, IL-10, TNF-α, IFN-γ, IL-17) were measured by cytometric beads array (CBA).

Results

The percentage of Tc1 in cITP was greatly higher than nITP and healthy controls (p < 0.05, p < 0.01). The percentage of Treg in nITP and cITP groups was remarkably lower than those in healthy control group (p < 0.05, p < 0.001); and according to platelet count analysis (PLT<50x10⁹/L or PLT>50x10⁹/L), Treg cells in ITP group were significantly lower than those in healthy control group (p < 0.001, p < 0.05). The percentage of CD4⁺CXCR3⁺ of cITP was significantly higher than healthy controls and nITP (p < 0.01, p < 0.05). The percentage of CD4⁺CCR6⁺ in cITP was significantly higher than healthy controls and nITP (p < 0.001, p < 0.05). The expression of PD-1 in cITP patients was higher than healthy control (p < 0.05), but there was no significant difference among nITP, pITP and cITP (p = 0.25). The levels of IL-2, IFN-γ and TNFα in nITP group and cITP group were significantly higher than those in healthy control group (p < 0.01, p < 0.05; p < 0.01, p < 0.05; p < 0.05, p < 0.05), and the level of IL-10 in nITP group was significantly higher than that in pITP group (p < 0.05).

Conclusion

Our results suggest that T lymphocyte immune dysfunction does exist in adult ITP patients and plays an important role in the pathogenesis of ITP.

Complex Interplay Between MAZR and Runx3 Regulates the Generation of Cytotoxic T Lymphocyte and Memory T Cells

The BTB zinc finger transcription factor MAZR (also known as PATZ1) controls, partially in synergy with the transcription factor Runx3, the development of CD8 lineage T cells. Here we explored the role of MAZR as well as combined activities of MAZR/Runx3 during cytotoxic T lymphocyte (CTL) and memory CD8+ T cell differentiation. In contrast to the essential role of Runx3 for CTL effector function, the deletion of MAZR had a mild effect on the generation of CTLs in vitro. However, a transcriptome analysis demonstrated that the combined deletion of MAZR and Runx3 resulted in much more widespread downregulation of CTL signature genes compared to single Runx3 deletion, indicating that MAZR partially compensates for loss of Runx3 in CTLs. Moreover, in line with the findings made in vitro, the analysis of CTL responses to LCMV infection revealed that MAZR and Runx3 cooperatively regulate the expression of CD8α, Granzyme B and perforin in vivo. Interestingly, while memory T cell differentiation is severely impaired in Runx3-deficient mice, the deletion of MAZR leads to an enlargement of the long-lived memory subset and also partially restored the differentiation defect caused by loss of Runx3. This indicates distinct functions of MAZR and Runx3 in the generation of memory T cell subsets, which is in contrast to their cooperative roles in CTLs. Together, our study demonstrates complex interplay between MAZR and Runx3 during CTL and memory T cell differentiation, and provides further insight into the molecular mechanisms underlying the establishment of CTL and memory T cell pools.

CD8 T cell nigral infiltration precedes synucleinopathy in early stages of Parkinson's disease

There is no consensus on the exact role of the adaptive immune system in Parkinson's disease pathogenesis, although there is increasing evidence that it is somehow involved. Moreover, T cell infiltration in the brain has not been thoroughly studied in Parkinson's disease and no study has assessed the infiltration in incidental Lewy body diseases cases that are considered to be early presymptomatic stages of the disease. In this study, we performed an immunohistochemistry/immunofluorescence quantitative and phenotypic assessment of T cell infiltration in human substantia nigra pars compacta and analysed the correlations with neuronal death and synucleinopathy throughout different stages of the disease. We included two groups of incidental Lewy disease in the study. One of the groups, which is believed to be the earliest stage of the disease, showed α-synuclein aggregates only in the olfactory bulb. The second group also presented α-synuclein aggregates in the substantia nigra. We also assessed the formation of different α-synuclein aggregates throughout the different stages of the unified staging system for Lewy body disorders (I to IV). We found that CD8 T cells were increased in diagnosed Parkinson's disease cases compared to the control group and their density positively correlated with neuronal death. Some of the infiltrating CD8 T cells were indeed contacting dopaminergic neurons. No differences were found regarding CD4 T cells. In the earliest stage of the disease, when substantia nigra α-synuclein aggregation is absent, we found a robust CD8 T cell infiltration and no dopaminergic neuronal death yet. Conversely, in the next stage we found neuronal loss and a milder CD8 T cell infiltration. CD8 T cell infiltration paralleled that of α-synuclein accumulation and neuronal death throughout stages II to IV. We also confirmed that CD8 T cells in charge of immune surveillance and involved in the aetiopathogenesis of the disease are equipped with cytolytic enzymes (granzyme A, B and K) and/or proinflammatory cytokines (interferon gamma), and that phenotypic differences were observed between early and late stages of the disease. We also demonstrate that a high proportion of nigral CD8 T cells are tissue resident memory T cells. Our results show that nigral cytotoxic CD8 T cell infiltration is an earlier pathogenic event than α-synuclein aggregation and neuronal death and that it parallels the progression of neuronal death and synucleinopathy in Parkinson's disease. Overall, our study suggests that CD8 T cell cytotoxic attack may initiate and propagate neuronal death and synucleinopathy in Parkinson's disease.

Does Antigen Glycosylation Impact the HIV-Specific T Cell Immunity?

It is largely unknown how post-translational protein modifications, including glycosylation, impacts recognition of self and non-self T cell epitopes presented by HLA molecules. Data in the literature indicate that O- and N-linked glycosylation can survive epitope processing and influence antigen presentation and T cell recognition. In this perspective, we hypothesize that glycosylation of viral proteins and processed epitopes contribute to the T cell response to HIV. Although there is some evidence for T cell responses to glycosylated epitopes (glyco-epitopes) during viral infections in the literature, this aspect has been largely neglected for HIV. To explore the role of glyco-epitope specific T cell responses in HIV infection we conducted in silico and ex vivo immune studies in individuals with chronic HIV infection. We found that in silico viral protein segments with potentially glycosylable epitopes were less frequently targeted by T cells. Ex vivo synthetically added glycosylation moieties generally masked T cell recognition of HIV derived peptides. Nonetheless, in some cases, addition of simple glycosylation moieties produced neo-epitopes that were recognized by T cells from HIV infected individuals. Herein, we discuss the potential importance of these observations and compare limitations of the employed technology with new methodologies that may have the potential to provide a more accurate assessment of glyco-epitope specific T cell immunity. Overall, this perspective is aimed to support future research on T cells recognizing glycosylated epitopes in order to expand our understanding on how glycosylation of viral proteins could alter host T cell immunity against viral infections.

Thrombin-PAR1 signaling in pancreatic cancer promotes an immunosuppressive microenvironment

Essentials Elimination of PDAC tumor cell PAR1 increased cytotoxic T cells and reduced tumor macrophages. PAR1KO PDAC cells are preferentially eliminated from growing tumors. Thrombin-PAR1 signaling in PDAC tumor cells drives an immunosuppressive gene signature. Csf2 and Ptgs2 are thrombin-PAR1 downstream immune suppressor genes in PDAC tumor cells. ABSTRACT: Background Pancreatic ductal adenocarcinoma (PDAC) is characterized by a prothrombotic state and a lack of host antitumor immune responsiveness. Linking these two key features, we previously demonstrated that tumor-derived coagulation activity promotes immune evasion. Specifically, thrombin-protease-activated receptor-1 (PAR1) signaling in mouse PDAC cells drives tumor growth by evading cytotoxic CD8a+ cells. Methods Syngeneic mixed cell tumor growth, transcriptional analyses, and functional tests of immunosuppressive response genes were used to identify cellular and molecular immune evasion mechanisms mediated by thrombin-PAR-1 signaling in mouse PDAC tumor cells. Results Elimination of tumor cell PAR1 in syngeneic graft studies increased cytotoxic T lymphocyte (CTL) infiltration and decreased tumor-associated macrophages in the tumor microenvironment. Co-injection of PAR1-expressing and PAR1-knockout (PAR-1KO ) tumor cells into immunocompetent mice resulted in preferential elimination of PAR-1KO cells from developing tumors, suggesting that PAR1-dependent immune evasion is not reliant on CTL exclusion. Transcriptomics analyses revealed no PAR1-dependent changes in the expression of immune checkpoint proteins and no difference in major histocompatibility complex-I cell surface expression. Importantly, thrombin-PAR1 signaling in PDAC cells upregulated genes linked to immunosuppression, including Csf2 and Ptgs2. Functional analyses confirmed that both Csf2 and Ptgs2 are critical for PDAC syngeneic graft tumor growth and overexpression of each factor partially restored tumor growth of PAR1KO cells in immunocompetent mice. Conclusions Our results provide novel insight into the mechanisms of a previously unrecognized pathway coupling coagulation to PDAC immune evasion by identifying PAR1-dependent changes in the tumor microenvironment, a PAR1-driven immunosuppressive gene signature, and Csf2 and Ptgs2 as critical PAR1 downstream targets.

Interferon-α-Induced Dendritic Cells Generated with Human Platelet Lysate Exhibit Elevated Antigen Presenting Ability to Cytotoxic T Lymphocytes

Given the recent advancements of immune checkpoint inhibitors, there is considerable interest in cancer immunotherapy provided through dendritic cell (DC)-based vaccination. Although many studies have been conducted to determine the potency of DC vaccines against cancer, the clinical outcomes are not yet optimal, and further improvement is necessary. In this study, we evaluated the potential ability of human platelet lysate (HPL) to produce interferon-α-induced DCs (IFN-DCs). In the presence of HPL, IFN-DCs (HPL-IFN-DCs) displayed high viability, yield, and purity. Furthermore, HPL-IFN-DCs displayed increased CD14, CD56, and CCR7 expressions compared with IFN-DCs produced without HPL; HPL-IFN-DCs induced an extremely higher number of antigen-specific cytotoxic T lymphocytes (CTLs) than IFN-DCs, which was evaluated with a human leukocyte antigen (HLA)-restricted melanoma antigen recognized by T cells 1 (MART-1) peptide. Additionally, the endocytic and proteolytic activities of HPL-IFN-DCs were increased. Cytokine production of interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-α was also elevated in HPL-IFN-DCs, which may account for the enhanced CTL, endocytic, and proteolytic activities. Our findings suggest that ex-vivo-generated HPL-IFN-DCs are a novel monocyte-derived type of DC with high endocytic and proteolytic activities, thus highlighting a unique strategy for DC-based immunotherapies.

Programmed death ligand-1 induction restrains the cytotoxic T lymphocyte response against microglia

Microglial cells are the main reservoir for HIV-1 within the brain and potential exists for negative immune checkpoint blockade therapies to purge this viral reservoir. Here, we investigated cytolytic responses of CD8⁺ T lymphocytes against microglia loaded with peptide epitopes. Initially, flow cytometric analysis demonstrated efficient killing of HIV-1 p24 AI9 or YI9 peptide-loaded splenocytes in MHC-matched recipients. Cytolytic killing of microglia was first demonstrated using ovalbumin (OVA) as a model antigen for in vitro cytotoxic T lymphocyte (CTL) assays. Peptide-loaded primary microglia obtained from programmed death ligand (PD-L) 1 knockout (KO) animals showed significantly more killing than cells from wild-type (WT) animals when co-cultured with activated CD8⁺ T-cells isolated from rAd5-OVA primed animals. Moreover, when peptide loaded-microglial cells from WT animals were treated with neutralizing α-PD-L1 Ab, significantly more killing was observed compared to either untreated or IgG isotype-treated cells. Most importantly, significantly increased in vivo killing of HIV-1 p24 YI9 peptide-loaded microglia from PD-L1 KO animals, as well as AI9 peptide-loaded BALB/c microglial cells treated with α-PD-L1, was observed within brains of rAd5-p24 primed-CNS boosted C57BL/6 or BALB/c mice, respectively. Finally, ex vivo responses of brain CD8⁺ T-cells in response to AI9 stimulation showed significantly increased IFN-γ and IL-2 production when treated with α-PD-1 Abs. Greater proliferation of CD8+ T-cells from the brain was also observed following blockade. Taken together, these studies demonstrate that PD-L1 induction on microglia restrains CTL responses and indicate that immune checkpoint blockade targeting this pathway may be beneficial in clearing viral brain reservoirs.

Human Peripheral Blood Dendritic Cell and T Cell Activation by Codium fragile Polysaccharide

Natural polysaccharides exhibit an immunostimulatory effect with low toxicity in humans and animals. It has shown that polysaccharide extracted from Codium fragile (CFP) induces anti-cancer immunity by dendritic cell (DC) activation, while the effect of CFP has not examined in the human immune cells. In this study, we found that CFP promoted the upregulation of CD80, CD83 and CD86 and major histocompatibility complex (MHC) class I and II in human monocyte-derived dendritic cells (MDDCs). In addition, CFP induced the production of proinflammatory cytokines in MDDCs. Moreover, CFP directly induced the activation of Blood Dendritic Cell Antigen (BDCA)1⁺ and BDCA3⁺ subsets of human peripheral blood DCs (PBDCs). The CFP-stimulated BDCA1⁺ PBDCs further promoted activation and proliferation of syngeneic CD4 T cells. The CFP-activated BDCA3⁺ PBDCs activated syngeneic CD8 T cells, which produced cytotoxic mediators, namely, cytotoxic T lymphocytes. These results suggest that CFP may be a candidate molecule for enhancing immune activation in humans.

The Effects of Asbestos Fibers on Human T Cells

Asbestos exposure causes malignant tumors such as lung cancer and malignant mesothelioma. The effects of asbestos fibers on immunocompetent cells, however, have not been well studied. Asbestos physically comprises a fibrous substance, which differs from silica particles which are a particulate substance, although chemically it is a mineral silicate. Since silicosis patients previously exposed to silica particles often suffer from lung and autoimmune diseases, it is clear that silica exposure impairs immune tolerance. Similarly, asbestos may alter the immune system in asbestos-exposed individuals. Given that malignant tumors can result following exposure to asbestos, the attenuation of anti-tumor immunity in cases of asbestos exposure is an important area of investigation. We observed the effect of asbestos fibers on T lymphocytes, such as CD8+ cytotoxic T lymphocytes (CTLs), CD4+ helper T (Th), and regulatory T (Treg) cells, and showed that anti-tumor immunity was attenuated, as demonstrated in a system that stimulates fresh cells isolated from peripheral blood in vitro and a system that is continuously exposed to a cell line. In this manuscript, we introduce the experiments and results of studies on CTLs, as well as Th and Treg cells, and discuss how future changes in immunocompetent cells induced by asbestos fibers can be clinically linked.

Novel Survivin Peptides Screened With Computer Algorithm Induce Cytotoxic T Lymphocytes With Higher Cytotoxic Efficiency to Cancer Cells

The identification of novel biomarkers and therapeutic targets in advanced cancer is critical for improving cancer diagnosis and therapeutics. Survivin (SV) is highly expressed predominantly in most cancer cells and tissues but is absent or undetectable in terminally differentiated normal adult tissues. Therefore, it functions as an almost universal tumor antigen. Peptides are short chains of amino acids linked by peptide bonds. To obtain novel SV decamers that are able to induce SV-specific cytotoxic T lymphocytes (CTLs) with a higher cytotoxic efficiency against cancer cells, major histocompatibility complex (MHC) peptide binding algorithms were conducted to predict nine modified SV₉₅ decamers (from SV_95–2 to SV_95–10) based on the natural SV_95–104 peptide sequence of ELTLGEFLKL (here defined as SV_95–1). The fluorescent density of each SV₉₅ peptide was determined by a MHC stability assay, followed by the generation of SV₉₅-specific CTLs with each SV₉₅ peptide (from SV_95–1 to SV_95–10) and human dendritic cells (DCs) loaded with Poly(lactic-co-glycolic) acid (PLGA) nanoparticles encapsulated with SV₉₅ peptide. Finally, IFN-γ ELISpot and CytoTox 96^® Non-Radioactive Cytotoxicity Assays were employed to verify their cytotoxic efficiency of the SV₉₅-specific CTLs generated with the corresponding artificial antigen presenting cells (aAPCs) containing SV₉₅ (SV_95–1 to SV_95–10) peptide. Furthermore, the cytotoxicity of the SV₉₅ specific CTLs generated with nine mutated SV₉₅ peptides was compared to the one generated with natural SV_95–1 peptide and TIL2080 cells. The results indicated that the HLA-A2-restricted mutated SV₉₅ epitope decamers (SV_95–6 and SV_95–7) showed significant higher binding ability compared to natural peptide SV_95–1 in MHC stability assay. More importantly, SV_95–specific CTLs with higher cytotoxicity were successfully induced with both SV_95–6 and SV_95–7 peptides, which significantly eliminated target cells (not only SV_95–1 peptide pulsed T2 cells, but also both HLA-A2 and SV positive cancer cells) when compared to those generated with natural SV_95–1 peptide and TIL2080 cells. These findings suggest that the SV_95–6 and SV_95–7 peptides are two novel HLA-A2-restricted CTL epitopes and may be useful for the immunotherapy for patients with survivin expressing cancer.

Role of cytotoxic T lymphocytes and interferon-γ in coronavirus infection: Lessons from murine coronavirus infections in mice

Murine coronavirus (CoV) is a beta-CoV that infects mice by binding to carcinoembryonic antigen-related cell adhesion molecule 1. Intraperitoneal infection with the murine CoV strain JHM (JHMV) induces acute mild hepatitis in mice. While both innate and acquired immune responses play a significant role in the protection against murine CoV infection in mice, CD8⁺ cytotoxic T lymphocytes (CTLs) and interferon-γ are essential for viral clearance in JHMV-induced hepatitis. In addition, CoVs are characterized by high diversity, caused by mutations, recombination, and gene gain/loss. 25V16G is an immune-escape JHMV variant, which lacks a dominant CTL epitope. By evading immune responses, 25V16G establishes persistent infections, leading to granulomatous serositis in interferon-γ-deficient mice. These examples of CoV-associated pathogenesis in mice might provide useful information on other CoV infections, including coronavirus disease 2019 (COVID-19).

The Superior Ability of Human BDCA3+ (CD141+) Dendritic Cells (DCs) to Cross-Present Antigens Derived From Necrotic Lung Cancer Cells

Dendritic cells (DCs) play a key role in initiating and regulating the immune responses to pathogens, self-antigens, and cancers. Human blood DCs comprise a family of different subsets: plasmacytoid DCs (pDCs) and CD16⁺, CD1c/BDCA1⁺, and BDCA3⁺ (CD141⁺) myeloid DCs and possess different phenotypes and functional characteristics. Lung cancer is the most common cancer, with the highest morbidity and mortality in the world. However, which DC subset plays a leading role in the lung cancer immune responses is unclear. We reanalyzed C-type lectin domain family 9 member A (CLEC9A) and CD141 (THBD) gene expression profiles from the Cancer Genome Atlas (TCGA) database and performed the Kaplan-Meier survival analysis of overall survival for several cancers according to their expression levels. Next, we investigated the capacities of five human blood DC subsets to stimulate T cell proliferation and capture, process and (cross-) present tumor antigen. Human BDCA3⁺ (CD141⁺) DCs have a superior capacity to stimulate allogeneic CD4⁺T cells proliferation and induce superior Th1 response compared with other DC subsets. Interestingly, toll-like receptor (TLR) agonists have little effect on DCs to induce the proliferation of naïve CD4⁺ T cells, but contribute to their differentiation. Importantly, BDCA3⁺ (CD141⁺) DCs possess the most potent ability to cross-present human tumor antigen after their uptake of necrotic lung cancer cells despite their lower antigen uptake. These findings suggest that human BDCA3⁺ (CD141⁺) DCs are critical mediators of cytotoxic T lymphocyte responses against EGFR-positive lung cancer. Therefore, our findings may provide theoretical basis for the development of DC-based antitumor vaccines.

Peptide vaccine as an adjuvant therapy for glypican-3-positive hepatocellular carcinoma induces peptide-specific CTLs and improves long prognosis

There is no established postoperative adjuvant therapy for hepatocellular carcinoma (HCC), and improvement of patient prognosis has been limited. We conducted long‐term monitoring of patients within a phase II trial that targeted a cancer antigen, glypican‐3 (GPC3), specifically expressed in HCC. We sought to determine if the GPC3 peptide vaccine was an effective adjuvant therapy by monitoring disease‐free survival and overall survival. We also tracked GPC3 immunohistochemical (IHC) staining, CTL induction, and postoperative plasma GPC3 for a patient group that was administered the vaccine (n = 35) and an unvaccinated patient group that underwent surgery only (n = 33). The 1‐y recurrence rate after surgery was reduced by approximately 15%, and the 5‐y and 8‐y survival rates were improved by approximately 10% and 30%, respectively, in the vaccinated group compared with the unvaccinated group. Patients who were positive for GPC3 IHC staining were more likely to have induced CTLs, and 60% survived beyond 5 y. Vaccine efficacy had a positive relationship with plasma concentration of GPC3; high concentrations increased the 5‐y survival rate to 75%. We thus expect GPC3 vaccination in patients with HCC, who are positive for GPC3 IHC staining and/or plasma GPC3 to induce CTL and have significantly improved long‐term prognosis.

E. coli-Produced Monophosphoryl Lipid a Significantly Enhances Protective Immunity of Pandemic H1N1 Vaccine

Emerging influenza viruses pose an extreme global risk to human health, resulting in an urgent need for effective vaccination against influenza infection. Adjuvants are vital components that can improve vaccine efficacy, yet only a few adjuvants have been licensed in human vaccines. Here, we investigate the adjuvant effects of Escherichia coli-produced monophosphoryl lipid A (MPL), named EcML, in enhancing the immunogenicity and efficacy of an influenza vaccine. Similar to MPL, EcML activated dendritic cells and enhanced the antigen processing of cells in vitro. Using ovalbumin (OVA) as a model antigen, EcML increased OVA-specific antibody production, cytotoxic T lymphocyte activity. The safety of EcML was demonstrated as being similar to that of MPL by showing not significant in vitro cell cytotoxicity but transient systemic inflammatory responses within 24 h in OVA immunized mice. Importantly, mice vaccinated with pandemic H1N1 (pH1N1) vaccine antigen, combined with EcML, were fully protected from pH1N1 virus infection by enhanced influenza-specific antibody titers, hemagglutination inhibition titers, and IFN-γ- secreting cells. Taken together, our results strongly suggest that EcML might be a promising vaccine adjuvant for preventing influenza virus infection.

Induction of adaptive immune responses against antigens incorporated within the capsid of simian virus 40

Simian virus 40 (SV40) is a monkey polyomavirus. The capsid structure is icosahedral and comprises VP1 units that measure 45 nm in diameter. Five SV40 VP1 molecules form one pentamer subunit, and a single icosahedral subunit comprises 72 pentamers; a single SV40 VP1 capsid comprises 360 SV40 VP1 molecules. In a previous study, we showed that an influenza A virus matrix protein 1 (M1) CTL epitope inserted within SV40 virus-like particles (VLPs) induced cytotoxic T lymphocytes (CTLs) without the need for an adjuvant. Here, to address whether SV40 VLPs induce adaptive immune responses against VLP-incorporated antigens, we prepared SV40 VLPs containing M1 or chicken ovalbumin (OVA). This was done by fusing M1 or OVA with the carboxyl terminus of SV40 VP2 and co-expressing them with SV40 VP1 in insect cells using a baculovirus vector. Intraperitoneal (i.p.) or intranasal administration of SV40 VLPs incorporating M1 induced the production of CTLs specific for the M1 epitope without the requirement for adjuvant. The production of antibodies against SV40 VLPs was also induced by i.p. administration of SV40 VLPs in the absence of adjuvant. Finally, the administration of SV40 VLPs incorporating OVA induced anti-OVA antibodies in the absence of adjuvant; in addition, the level of antibody production was comparable with that after i.p. administration of OVA plus alum adjuvant. These results suggest that the SV40 capsid incorporating foreign antigens can be used as a vaccine platform to induce adaptive immune responses without the need for adjuvant.

Cancer immunotherapy using a polysaccharide from Codium fragile in a murine model

Natural polysaccharides have shown immune modulatory effects with low toxicity in both animal and human models. A previous study has shown that the polysaccharide from Codium fragile (CFP) promotes natural killer (NK) cell activation in mice. Since NK cell activation is mediated by dendritic cells (DCs), we examined the effect of CFP on DC activation and evaluated the subsequent induction of anti-cancer immunity in a murine model. Treatment with CFP induced activation of bone marrow-derived dendritic cells (BMDCs). Moreover, subcutaneous injection of CFP promoted the activation of spleen and lymph node DCs in vivo. CFP also induced activation of DCs in tumor-bearing mice, and combination treatment with CFP and ovalbumin (OVA) promoted OVA-specific T cell activation, which consequently promoted infiltration of IFN-γ-and TNF-α-producing OT-1 and OT-II cells into the tumors. Moreover, combination treatment using CFP and cancer self-antigen efficiently inhibited B16 tumor growth in the mouse model. Treatment with CFP also enhanced anti-PD-L1 antibody mediated anti-cancer immunity in the CT-26 carcinoma-bearing BALB/c mice. Taken together these data suggest that CFP may function as an adjuvant in the treatment of cancer by enhancing immune activation.

Abbreviations

CFP: Codium fragile polysaccharide; NK: natural killer; IFN: interferon; TNF: tumor necrosis factor; IL: interleukin; tdLN: tumor draining lymph node; BMDC: bone marrow-derived dendritic cell; OVA: ovalbumin; Ab: antibody; Ag: antigen; DC: dendritic cell; CTL: cytotoxic T lymphocyte; APC: antigen-presenting cell; pDC: plasmacytoid dendritic cell; mDC: myeloid dendritic cell; MHC: major histocompatibility complex; CR3: complement receptor type 3; TLR: Toll-like receptor; LPS: lipopolysaccharide; SP: sulfated polysaccharide; TRP2: tyrosinase-related protein 2; SR-A: scavenger receptor-A

Annona muricata L.-Derived Polysaccharides as a Potential Adjuvant to a Dendritic Cell-Based Vaccine in a Thymoma-Bearing Model

Dendritic cells (DCs) are powerful antigen-presenting cells that are often used to evaluate adjuvants, particularly for adjuvant selection for various vaccines. Here, polysaccharides (named ALP) isolated from leaves of Annona muricata L., which are used in traditional medicine such as for bacterial infections and inflammatory diseases, were evaluated as an adjuvant candidate that can induce anti-tumor activity. We first confirmed the phenotypic (surface molecules, cytokines, antigen uptake, and antigen-presenting ability) and functional alterations (T cell proliferation/activation) of DCs in vitro. We also confirmed the adjuvant effect by evaluating anti-tumor activity and immunity using an ALP-treated DC-immunized mouse model. ALP functionally induced DC maturation by up-regulating the secretion of Th1-polarizing pro-inflammatory cytokines, the expression of surface molecules, and antigen-presenting ability. ALP triggered DC maturation, which is dependent on the activation of the MAPK and NF-κB signaling pathways. ALP-activated DCs showed an ample capacity to differentiate naive T cells to Th1 and activated CD8⁺ T cells effectively. The systemic administration of DCs that pulse ALP and ovalbumin peptides strongly increased cytotoxic T lymphocyte (CTL) activity (by 9.5% compared to that in the control vaccine groups), the generation of CD107a-producing multifunctional T cells, and Th1-mediated humoral immunity, and caused a significant reduction (increased protection by 29% over that in control vaccine groups) in tumor growth. ALP, which triggers the Th1 and CTL response, provides a basis for a new adjuvant for various vaccines.

A systematic re-examination of processing of MHCI-bound antigenic peptide precursors by endoplasmic reticulum aminopeptidase 1

Endoplasmic reticulum aminopeptidase 1 (ERAP1) trims antigenic peptide precursors to generate mature antigenic peptides for presentation by major histocompatibility complex class I (MHCI) molecules and regulates adaptive immune responses. ERAP1 has been proposed to trim peptide precursors both in solution and in preformed MHCI-peptide complexes, but which mode is more relevant to its biological function remains controversial. Here, we compared ERAP1-mediated trimming of antigenic peptide precursors in solution or when bound to three MHCI alleles, HLA-B*58, HLA-B*08, and HLA-A*02. For all MHCI-peptide combinations, peptide binding onto MHCI protected against ERAP1-mediated trimming. In only a single MHCI-peptide combination, trimming of an HLA-B*08-bound 12-mer progressed at a considerable rate, albeit still slower than in solution. Results from thermodynamic, kinetic, and computational analyses suggested that this 12-mer is highly labile and that apparent on-MHC trimming rates are always slower than that of MHCI-peptide dissociation. Both ERAP2 and leucine aminopeptidase, an enzyme unrelated to antigen processing, could trim this labile peptide from preformed MHCI complexes as efficiently as ERAP1. A pseudopeptide analogue with high affinity for both HLA-B*08 and the ERAP1 active site could not promote the formation of a ternary ERAP1/MHCI/peptide complex. Similarly, no interactions between ERAP1 and purified peptide-loading complex were detected in the absence or presence of a pseudopeptide trap. We conclude that MHCI binding protects peptides from ERAP1 degradation and that trimming in solution along with the dynamic nature of peptide binding to MHCI are sufficient to explain ERAP1 processing of antigenic peptide precursors.

Identification of Novel Cytotoxic T Lymphocyte Epitopes of Drug- Resistance Related Protein InhA from Mycobacterium tuberculosis

BACKGROUND

Tuberculosis (TB) caused by Mycobacterium tuberculosis (MTB), especially the drug-resistant MTB, poses serious challenges to human healthcare worldwide. Cytotoxic T lymphocytes (CTLs) play a vital role in immune defense against MTB.

OBJECTIVE

To identify novel CTL epitopes that could induce cellular immunity against MTB infections.

METHODS

The HLA-A*0201 restricted CTL epitopes of the drug-resistant protein InhA from MTB were predicted by online algorisms and synthesized by the Fmoc solid phase method. The candidate peptides were used to induce CTLs from human peripheral blood mononuclear cells (PBMCs) of HLA-A*0201 healthy donors and the HLA-2.1/Kb mice. IFN-γ productions of CTLs were detected by enzyme linked immunospot assay (ELISPOT), flow cytometry and enzyme-linked immunosorbent assay (ELISA), and cytotoxicity was analyzed by lactate dehydrogenase (LDH) assay.

RESULTS

A group of 4 epitopes were screened out with high affinities to HLA-A*0201. ELISPOT and flow cytometry analysis indicated these peptides significantly induced that IFN-γ release of CTLs from the HLA-A*0201+/PPD+ donors, as the mutant analogues had more potent stimulation effects. LDH assay showed that CTLs from PPD+ donors and the immunized mice exhibited significant cytotoxicity and low cross-reactivity. ELISA analysis revealed comparative levels of IFN-γ were released by CTLs isolated from the mice spleen.

CONCLUSION

Our study has identified 4 novel CTL epitopes of InhA that could elicit potent CTL immunity, establishing a foundation for the development of multivalent peptide vaccines against the drug-resistant MTB.

Yonsei Criteria, a Potential Linkage to Intratumoral Foxp3⁺/CD8⁺ Ratio for the Prediction of Oncologic Outcomes in Resected Left-Sided Pancreatic Cancer

PURPOSE

This study sought to investigate associations among Yonsei criteria (tumor confined to the pancreas, intact fascia layer between the distal pancreas and the left adrenal gland and kidney, and tumor located more than 1-2 cm from the celiac axis) and tumor infiltrating lymphocytes in pancreatic cancer.

MATERIALS AND METHODS

Patients who underwent curative distal pancreatectomy due to left-sided pancreatic cancer from January 2000 to December 2011 were enrolled. Follow-up was completed September 30, 2015.

RESULTS

Fifty patients were enrolled. Having ≥ two metastatic lymph nodes (LNs, p=0.002), intraoperative transfusion (p=0.011), low levels of tumor infiltrating CD8⁺ T-cells (p=0.001), and a high Foxp3⁺/CD8⁺ ratio (p=0.009) were independent risk factors for disease-free survival. Not satisfying the Yonsei criteria (p=0.021), having ≥ two metastatic LNs (p=0.032), low levels of tumor infiltrating CD8⁺ T-cells (p=0.040) and a high Foxp3⁺/CD8⁺ ratio (p=0.032) were associated with unfavorable overall survival. High levels of CA19-9 and not satisfying the Yonsei criteria were significantly associated with a high Foxp3⁺/CD8⁺ ratio [Exp(β)=3.558; 95% confidence inverval: 1.000-12.658; p=0.050].

CONCLUSION

Yonsei criteria may be clinically detectable biologic marker with which to predict immunologic status and survival in pancreatic cancer patients.

Trial watch: chemotherapy-induced immunogenic cell death in immuno-oncology

The term ‘immunogenic cell death’ (ICD) denotes an immunologically unique type of regulated cell death that enables, rather than suppresses, T cell-driven immune responses that are specific for antigens derived from the dying cells. The ability of ICD to elicit adaptive immunity heavily relies on the immunogenicity of dying cells, implying that such cells must encode and present antigens not covered by central tolerance (antigenicity), and deliver immunostimulatory molecules such as damage-associated molecular patterns and cytokines (adjuvanticity). Moreover, the host immune system must be equipped to detect the antigenicity and adjuvanticity of dying cells. As cancer (but not normal) cells express several antigens not covered by central tolerance, they can be driven into ICD by some therapeutic agents, including (but not limited to) chemotherapeutics of the anthracycline family, oxaliplatin and bortezomib, as well as radiation therapy. In this Trial Watch, we describe current trends in the preclinical and clinical development of ICD-eliciting chemotherapy as partner for immunotherapy, with a focus on trials assessing efficacy in the context of immunomonitoring.

Abscopal effect following nivolumab induction in a patient with metastatic renal cell carcinoma-unique pathological features of the primary specimen: A case report

The case of a patient with metastatic renal cell carcinoma who exhibited the abscopal effect following treatment by anti-programmed death-1 (PD-1) antibody is presented. A 40-year-old woman was diagnosed with an 8.2-cm renal tumor without distant metastases, and radical nephrectomy was subsequently performed. Pathological examination revealed a clear cell renal cell carcinoma. At 3 months after surgery, the patient developed one lung metastasis. Following treatment with interferon and three types of tyrosine kinase inhibitors, anti-PD1 antibody (nivolumab) was started. During the treatment, para-aortic/supraclavicular lymph nodes and several lung lesions remained, although other lesions decreased markedly. The patient was subsequently treated by palliative radiotherapy to the para-aortic and supraclavicular lymph nodes for pain control. After the radiotherapy, the lung lesions previously refractory to nivolumab started to decrease, probably due to an abscopal effect. Additionally, the laboratory data and Karnofsky Performance Status improved. Histological re-examination of the primary lesion revealed heterogeneity of the immunological microenvironment, which may be associated with the heterogeneity of treatment sensitivity.

A new in vitro model of polymyositis reveals CD8+ T cell invasion into muscle cells and its cytotoxic role

Objectives

The hallmark histopathology of PM is the presence of CD8⁺ T cells in the non-necrotic muscle cells. The aim of this study was to clarify the pathological significance of CD8⁺ T cells in muscle cells.

Methods

C2C12 cells were transduced retrovirally with the genes encoding MHC class I (H2K^b) and SIINFEKL peptide derived from ovalbumin (OVA), and then differentiated to myotubes (H2K^bOVA-myotubes). H2K^bOVA-myotubes were co-cultured with OT-I CD8⁺ T cells derived from OVA-specific class I restricted T cell receptor transgenic mice as an in vitro model of PM to examine whether the CD8⁺ T cells invade into the myotubes and if the myotubes with the invasion are more prone to die than those without. Muscle biopsy samples from patients with PM were examined for the presence of CD8⁺ T cells in muscle cells. The clinical profiles were compared between the patients with and without CD8⁺ T cells in muscle cells.

Results

Analysis of the in vitro model of PM with confocal microscopy demonstrated the invasion of OT-I CD8⁺ T cells into H2K^bOVA-myotubes. Transmission electron microscopic analysis revealed an electron-lucent area between the invaded CD8⁺ T cell and the cytoplasm of H2K^bOVA-myotubes. The myotubes invaded with OT-I CD8⁺ T cells died earlier than the uninvaded myotubes. The level of serum creatinine kinase was higher in patients with CD8⁺ T cells in muscle cells than those without these cells.

Conclusion

CD8⁺ T cells invade into muscle cells and contribute to muscle injury in PM. Our in vitro model of PM is useful to examine the mechanisms underlying muscle injury induced by CD8⁺ T cells.

Efficacy of the NCCV Cocktail-1 vaccine for refractory pediatric solid tumors: A phase I clinical trial

Pediatric refractory solid tumors are aggressive malignant diseases, resulting in an extremely poor prognosis. KOC1, FOXM1, and KIF20A are cancer antigens that could be ideal targets for anticancer immunotherapy against pediatric refractory solid tumors with positive expression for these antigens. This nonrandomized, open‐label, phase I clinical trial evaluated the safety and efficacy of the NCCV Cocktail‐1 vaccine, which is a cocktail of cancer peptides derived from KOC1, FOXM1, and KIF20A, in patients with pediatric refractory solid tumors. Twelve patients with refractory pediatric solid tumors underwent NCCV Cocktail‐1 vaccination weekly by intradermal injections. The primary endpoint was the safety of the NCCV Cocktail‐1 vaccination, and the secondary endpoints were the immune response, as measured by interferon‐r enzyme‐linked immunospot assay, and the clinical outcomes including tumor response and progression‐free survival. The NCCV Cocktail‐1 vaccine was well tolerated. The clinical response of this trial showed that 4 patients had stable disease after 8 weeks and 2 patients maintained remission for >11 months. In 4, 8, and 5 patients, the NCCV Cocktail‐1 vaccine induced the sufficient number of peptide‐specific CTLs for KOC1, FOXM1, and KIF20A, respectively. Patients with high peptide‐specific CTL frequencies for KOC1, FOXM1, and KIF20A had better progression‐free survival than those with low frequencies. The findings of this clinical trial showed that the NCCV Cocktail‐1 vaccine could be a novel therapeutic strategy, with adequate effects against pediatric refractory solid tumors. Future large‐scale trials should evaluate the efficacy of the NCCV Cocktail‐1 vaccination.

The Role of Nanovaccine in Cross-Presentation of Antigen-Presenting Cells for the Activation of CD8+ T Cell Responses

Explosive growth in nanotechnology has merged with vaccine development in the battle against diseases caused by bacterial or viral infections and malignant tumors. Due to physicochemical characteristics including size, viscosity, density and electrostatic properties, nanomaterials have been applied to various vaccination strategies. Nanovaccines, as they are called, have been the subject of many studies, including review papers from a material science point of view, although a mode of action based on a biological and immunological understanding has yet to emerge. In this review, we discuss nanovaccines in terms of CD8+ T cell responses, which are essential for antiviral and anticancer therapies. We focus mainly on the role and mechanism, with particular attention to the functional aspects, of nanovaccines in inducing cross-presentation, an unconventional type of antigen-presentation that activates CD8+ T cells upon administration of exogenous antigens, in dendritic cells followed by activation of antigen-specific CD8+ T cell responses. Two major intracellular mechanisms that nanovaccines harness for cross-presentation are described; one is endosomal swelling and rupture, and the other is membrane fusion. Both processes eventually allow exogenous vaccine antigens to be exported from phagosomes to the cytosol followed by loading on major histocompatibility complex class I, triggering clonal expansion of CD8+ T cells. Advancement of nanotechnology with an enhanced understanding of how nanovaccines work will contribute to the design of more effective and safer nanovaccines.

Regulation of programmed death-ligand 1 expression in response to DNA damage in cancer cells: Implications for precision medicine

Anti‐programmed death‐1 (PD‐1)/programmed death‐ligand 1 (PD‐L1) therapy, which is one of the most promising cancer therapies, is licensed for treating various tumors. Programmed death‐ligand 1, which is expressed on the surface of cancer cells, leads to the inhibition of T lymphocyte activation and immune evasion if it binds to the receptor PD‐1 on CTLs. Anti‐PD‐1/PD‐L1 Abs inhibit interactions between PD‐1 and PD‐L1 to restore antitumor immunity. Although certain patients achieve effective responses to anti‐PD‐1/PD‐L1 therapy, the efficacy of treatment is highly variable. Clinical trials of anti‐PD‐1/PD‐L1 therapy combined with radiotherapy/chemotherapy are underway with suggestive evidence of favorable outcome; however, the molecular mechanism is largely unknown. Among several molecular targets that can influence the efficacy of anti‐PD‐1/PD‐L1 therapy, PD‐L1 expression in tumors is considered to be a critical biomarker because there is a positive correlation between the efficacy of combined treatment protocols and PD‐L1 expression levels. Therefore, understanding the mechanisms underlying the regulation of PD‐L1 expression in cancer cells, particularly the mechanism of PD‐L1 expression following DNA damage, is important. In this review, we consider recent findings on the regulation of PD‐L1 expression in response to DNA damage signaling in cancer cells.

Dendritic cells loaded with CD44+ CT-26 colon cell lysate evoke potent antitumor immune responses

Increasing evidence supports the concept that cancer stem cells (CSCs) are responsible for cancer progression and metastasis, therapy resistance and relapse. In addition to conventional therapies for colon cancer, the development of immunotherapies targeting cancer stem cells appears to be a promising strategy to suppress tumor recurrence and metastasis. In the present study, dendritic cells (DCs) were pulsed with whole-tumor cell lysates or total RNA of CD44⁺ colon cancer stem cells (CCSCs) isolated from mouse colon adenocarcinoma CT-26 cell cultures and investigated for their antitumor immunity against CCSCs in vivo and in vitro. In a model of colon adenocarcinoma using BALB/c mice, a sequential reduction in tumor volume and weight was associated with an extended survival in tumor-bearing mice vaccinated with DCs pulsed with RNA or CCSC lysate. In addition, a lactate dehydrogenase assay indicated that cytotoxic T-cells derived from the treated mice exhibited strong cytotoxic activity. Additionally, an enzyme-linked immunosorbent assay revealed that the cytotoxic T-cells of the treated mice released higher levels of interferon-γ against CCSCs compared with those of the control group. In all experiments, the antitumor efficacy of the lysate-pulsed DC-treated and RNA-pulsed DC-treated groups were significantly higher compared with that of the DC-treated and control groups. The results of the present study indicated the potential use of DCs pulsed with cancer stem cell lysates as a potent therapeutic antigen to target CSCs in colon cancer. Additionally, the results provided a rationale for using lysate-pulsed DCs in vivo to eliminate residual tumor deposits in post-operative patients.

Heat shock protein 105 peptide vaccine could induce antitumor immune reactions in a phase I clinical trial

Heat shock protein 105 (HSP105) is overexpressed in many cancers, including colorectal cancer (CRC) and esophageal cancer (EC). We carried out a phase I clinical trial of HLA-A24- and HLA-A2-restricted HSP105 peptide vaccines in patients with CRC or EC. In this additional study of the trial, we examined the immunological efficacy of the novel vaccine. Thirty patients with advanced CRC or EC underwent HSP105 peptide vaccination. Immunological responses were evaluated by ex vivo and in vitro γ-interferon enzyme-linked immunospot assays and their correlation with patients' prognosis was analyzed. The HSP105 peptide vaccines induced peptide-specific CTLs in 15 of 30 patients. Among HLA-A24 patients (n = 15), 7 showed induction of CTLs only ex vivo, whereas among HLA-A2 patients (n = 15), 4 showed the induction ex vivo and 6 in vitro. Heat shock protein 105-specific CTL induction correlated with suppression of cancer progression and was revealed as a potential predictive biomarker for progression-free survival (P = .008; hazard ratio = 3.03; 95% confidence interval, 1.34-6.85) and overall survival (P = .025; hazard ratio = 2.72; 95% confidence interval, 1.13-6.52). Production of cytokines by HSP105 peptide-specific CTLs was observed at the injection sites (skin) and tumor tissues, suggesting that HSP105-specific CTLs not only accumulated at vaccination sites but also infiltrated tumors. Furthermore, we established 2 HSP105 peptide-specific CTL clones, which showed HSP105-specific cytokine secretion and cytotoxicity. Our results suggest that the HSP105 peptide vaccine could induce immunological effects in cancer patients and improve their prognosis.

Cx43-Gap Junctions Accumulate at the Cytotoxic Immunological Synapse Enabling Cytotoxic T Lymphocyte Melanoma Cell Killing

Upon tumor antigen recognition, cytotoxic T lymphocytes (CTLs) and target cells form specialized supramolecular structures, called cytotoxic immunological synapses, which are required for polarized delivery of cytotoxic granules. In previous reports, we described the accumulation of connexin 43 (Cx43)-formed gap junctions (GJs) at natural killer (NK) cell–tumor cell cytotoxic immunological synapse. In this report, we demonstrate the functional role of Cx43-GJs at the cytotoxic immunological synapse established between CTLs and melanoma cells during cytotoxicity. Using confocal microscopy, we evaluated Cx43 polarization to the contact site between CTLs isolated from pMEL-1 mice and B16F10 melanoma cells. We knocked down Cx43 expression in B16F10 cells and evaluated its role in the formation of functional GJs and the cytotoxic activity of CTLs, by calcein transfer and granzyme B activity assays, respectively. We found that Cx43 localizes at CTL/B16F10 intercellular contact sites via an antigen-dependent process. We also found that pMEL-1 CTLs but not wild-type naïve CD8⁺ T cells established functional GJs with B16F10 cells. Interestingly, we observed that Cx43-GJs were required for an efficient granzyme B activity in target B16F10 cells. Using an HLA-A2-restricted/MART-1-specific CD8⁺ T-cell clone, we confirmed these observations in human cells. Our results suggest that Cx43-channels are relevant components of cytotoxic immunological synapses and potentiate CTL-mediated tumor cell killing.