Cells In Tumor-draining Lymph Nodes Research Articles

Targeting Autocrine CCL5-CCR5 Axis Reprograms Immunosuppressive Myeloid Cells and Reinvigorates Antitumor Immunity.

The tumor-promoting potential of CCL5 has been proposed but remains poorly understood. We demonstrate here that an autocrine CCL5-CCR5 axis is a major regulator of immunosuppressive myeloid cells (IMC) of both monocytic and granulocytic lineages. The absence of the autocrine CCL5 abrogated the generation of granulocytic myeloid-derived suppressor cells and tumor-associated macrophages. In parallel, enhanced maturation of intratumoral neutrophils and macrophages occurred in spite of tumor-derived CCL5. The refractory nature of ccl5-null myeloid precursors to tumor-derived CCL5 was attributable to their persistent lack of membrane-bound CCR5. The changes in the ccl5-null myeloid compartment subsequently resulted in increased tumor-infiltrating cytotoxic CD8+ T cells and decreased regulatory T cells in tumor-draining lymph nodes. An analysis of human triple-negative breast cancer specimens demonstrated an inverse correlation between "immune CCR5" levels and the maturation status of tumor-infiltrating neutrophils as well as 5-year-survival rates. Targeting the host CCL5 in bone marrow via nanoparticle-delivered expression silencing, in combination with the CCR5 inhibitor Maraviroc, resulted in strong reductions of IMC and robust antitumor immunities. Our study suggests that the myeloid CCL5-CCR5 axis is an excellent target for cancer immunotherapy. Cancer Res; 77(11); 2857-68. ©2017 AACR.

Immunoregulatory Function of Lymphatic Endothelial Cells in Tumor-draining Lymph Nodes of Human Gastric Cancer.

Lymph node metastasis is the most important prognostic factor for patients with gastric cancer. Increasing evidence suggests that lymphatic endothelial cells (LECs) regulate immune responses. The aim of this study was to examine the effect of LECs on the activation of CD4+ T cells. We examined the impact of cancer cells on the phenotype and production of cytokines of LECs derived from tumor-draining lymph nodes. We showed that LECs inhibited CD4+ T cell production of cytokines, such as IL-2, IL-10, and INF-γ. The mRNA expression of programmed death-ligand 1 (PD-L1) and indoleamine 2, 3-dioxygenase (IDO) by LECs were significantly up-regulated when the LECs and CD4+ T cells were co-cultured with cells of the gastric cancer cell line, OCUM12. Intranodal LECs may be a key player in the induction of immune tolerance against cancer and in facilitating metastasis through lymphatic vessels in gastric cancer.

The Ribosomal Protein S19 Suppresses Antitumor Immune Responses via the Complement C5a Receptor 1.

Relatively little is known about factors that initiate immunosuppression in tumors and act at the interface between tumor cells and host cells. In this article, we report novel immunosuppressive properties of the ribosomal protein S19 (RPS19), which is upregulated in human breast and ovarian cancer cells and released from apoptotic tumor cells, whereupon it interacts with the complement C5a receptor 1 expressed on tumor infiltrating myeloid-derived suppressor cells. This interaction promotes tumor growth by facilitating recruitment of these cells to tumors. RPS19 also induces the production of immunosuppressive cytokines, including TGF-β, by myeloid-derived suppressor cells in tumor-draining lymph nodes, leading to T cell responses skewed toward Th2 phenotypes. RPS19 promotes generation of regulatory T cells while reducing infiltration of CD8+ T cells into tumors. Reducing RPS19 in tumor cells or blocking the C5a receptor 1-RPS19 interaction decreases RPS19-mediated immunosuppression, impairs tumor growth, and delays the development of tumors in a transgenic model of breast cancer. This work provides initial preclinical evidence for targeting RPS19 for anticancer therapy enhancing antitumor T cell responses.

Laminarin promotes anti-cancer immunity by the maturation of dendritic cells.

This research evaluates the effects of laminarin on the maturation of dendritic cells and on the in vivo activation of anti-cancer immunity. In vivo treatment of C56BL/6 mice with laminarin increased the expression levels of co-stimulatory molecules and the production of pro-inflammatory cytokines in spleen dendritic cells. Laminarin enhanced ovalbumin antigen presentation in spleen dendritic cells and promoted the proliferation of OT-I and OT-II T cells. Laminarin also induced the maturation of dendritic cells in tumor-draining lymph nodes and protected interferon-γ and tumor necrosis factor-α and proliferation of OT-I and OT-II T cells in tumors. The combination treatment of laminarin and ovalbumin inhibited B16-ovallbumin melanoma tumor growth and its liver metastasis by antigen-specific immune activation, including cytotoxic T lymphocyte activation and interferon-γ production. Thus, these data demonstrated the potential of laminarin as a new and useful immune stimulatory molecule for use in cancer immunotherapy.

Antitumor activity of orally administered maitake α-glucan by stimulating antitumor immune response in murine tumor.

Maitake α-glucan, YM-2A, isolated from Grifola frondosa, has been characterized as a highly α-1,6-branched α-1,4 glucan. YM-2A has been shown to possess an anti-virus effect in mice; however, it does not directly inhibit growth of the virus in vitro, indicating that the anti-virus effect of YM-2A might be associated with modulation of the host immune system. In this study, we found that oral administration of YM-2A could inhibit tumor growth and improve survival rate in two distinct mouse models of colon-26 carcinoma and B16 melanoma. Orally administered YM-2A enhanced antitumor immune response by increasing INF-γ-expressing CD4+ and CD8+ cells in the spleen and INF-γ-expressing CD8+ cells in tumor-draining lymph nodes. In vitro study showed that YM-2A directly activated splenic CD11b+ myeloid cells, peritoneal macrophages and bone marrow-derived dendritic cells, but did not affect splenic CD11b- lymphocytes or colon-26 tumor cells. YM-2A is more slowly digested by pancreatic α-amylase than are amylopectin and rabbit liver glycogen, and orally administered YM-2A enhanced the expression of MHC class II and CD86 on dendritic cells and the expression of MHC class II on macrophages in Peyer’s patches. Furthermore, in vitro stimulation of YM-2A increased the expression of pro-inflammatory cytokines in Peyer’s patch CD11c+ cells. These results suggest that orally administered YM-2A can activate dendritic cells and macrophages in Peyer’s patches, inducing systemic antitumor T-cell response. Thus, YM-2A might be a candidate for an oral therapeutic agent in cancer immunotherapy.

B cells inhibit the antitumor immunity against an established murine fibrosarcoma.

Despite the classic role of B cells in favoring the immune response, an inhibitory action of B lymphocytes in tumor immunity has emerged in certain studies. In methylcolanthrene-induced murine fibrosarcoma (MCC), the loss of immunogenicity and the establishment of tolerance are paralleled by systemic immune suppression and the appearance of B+IL-10+ cells in tumor-draining lymph nodes. The present study aimed to assess the role of the B+IL-10+ cell population in the immune evasion and tolerance induced by MCC through the depletion of B cells in mice at various times of tumor progression: Prior to or subsequent to tumor implantation. Tumor growth and immunological parameters were evaluated. B cell depletion prior to tumor inoculum enhanced tumor growth, initiating the onset of the tumor-induced systemic immune response; however, an increase in the T regulatory cells (Tregs) at the tumor-draining lymph node could account for tumor exacerbation. B cell depletion once the tumor was established resulted in decreased tumor growth and a delayed onset of tolerance. Additionally, B cell absence exacerbated T cell dependent-tumor rejection, reduced Tregs and increased cytotoxic CD8+ T cells. In vitro analysis showed a direct effect of B cells upon T cell proliferation. In conclusion, B cell depletion exerts opposite effects when performed prior to or subsequent to tumor implantation. In this initially immunogenic tumor, B cell absence would delay the establishment of immunological tolerance probably by unmasking a pre-existing antitumor response. The present findings elucidate the convenience of modulating B cells in the development of future and more effective immunotherapies against cancer.

Antitumor effects of oncolytic herpes simplex virus type 2 against colorectal cancer in vitro and in vivo.

BackgroundThe incidence of colorectal cancer (CRC) is on the rise. Furthermore, late-stage diagnoses and limited efficacious treatment options make CRC a complex clinical challenge. Therefore, a new therapeutic regimen with a completely novel therapeutic mechanism is necessary for CRC. In the present study, the therapeutic efficacy of oncolytic herpes simplex virus type 2 (oHSV2) in CRC was assessed in vitro and in vivo. oHSV2 is an oncolytic agent derived from herpes simplex virus type 2 that encodes granulocyte-macrophage colony-stimulating factor.Materials and methodsWe investigated the cytopathic effects of oHSV2 in CRC cell lines using the MTT assay. Then, cell cycle progression and apoptosis of oHSV2 were examined by flow cytometry. We generated a model of CRC with mouse CRC cell CT26 in BALB/c mice. The antitumor effects and adaptive immune response of oHSV2 were assessed in tumor-bearing mice. The therapeutic efficacy of oHSV2 was compared with the traditional chemotherapeutic agent, 5-fluorouracil.ResultsThe in vitro data showed that oHSV2 infected the CRC cell lines successfully and that the tumor cells formed a significant number of syncytiae postinfection. The oHSV2 killed cancer cells independent of the cell cycle and mainly caused tumor cells necrosis. The in vivo results showed that oHSV2 significantly inhibited tumor growth and prolonged survival of tumor-bearing mice without weight loss. With virus replication, oHSV2 not only resulted in a reduction of myeloid-derived suppressor cells and regulatory T cells in the spleen, but also increased the number of mature dendritic cells in tumor-draining lymph nodes and the effective CD4+T and CD8+T-cells in the tumor microenvironment.ConclusionOur study provides the first evidence that oHSV2 induces cell death in CRC in vitro and in vivo. These findings indicate that oHSV2 is an effective therapeutic cancer candidate that causes an oncolytic effect and recruits adaptive immune responses for an enhanced therapeutic impact, thus providing a potential therapeutic tool for treatment of CRC.

Molecular docking studies and ADMET predictions of pyrimidine coumarin scaffolds as potential IDO inhibitors

Indoleamine 2,3-dioxygenase (IDO) is emerging as an important new therapeutic drug target for the treatment of cancer. IDO catalyzes the rate-limiting step of tryptophan degradation through kynurenine pathway. Reduction in local tryptophan concentration and the production of immunomodulatory tryptophan metabolites contribute to the immunosuppressive effects of IDO. Presence of IDO on dendritic cells in tumor-draining lymph nodes leading to the activation of T cells results in formation of immunosuppressive microenvironment for the survival of tumor cells, shows the importance of IDO as a novel anticancer immunotherapy drug target. Pyrimidine has the unique ability to act through many different mechanisms and its multiple biological activities make it an ideal therapeutic agent in treating cancer. In this effort directed towards the discovery of novel, potent IDO inhibitors for the treatment of cancer. In the present study a library of pyrimidine derivatives has been designed and evaluated for their anti-cancer activity targeting IDO using various computational approaches. Twenty new pyrimidine series of compounds were designed and docking studies were performed. All of them have found to be successfully docked inside the active binding domain of IDO with a binding energy in a range of -4.59 to -9.53 Kcal/mol with predicted IC50 value range of 4.72 micro molar to 456.19 nano molar. On the other hand, calculated 2DQSAR molecular descriptor properties of the compounds showed promising ADME parameters and found to be in compliance with Lipinski's rule of five. Among all the twenty compounds tested, compound 14 (N’-(6-chloro-2-oxo-chromene-3-carbonyl)-4-(4-methoxyphenyl)-6-methyl-2-thioxo-3,4-dihydro-1H-pyrimidine-5-carbohydrazide) was found to be the best lead like molecule with a binding energy of -9.53 kcal/mol. Conclusively, newly designed compound 14 of the present study have shown promising anti-cancer potential worth considering for further evaluations.

Determination of a CD4+CD25-FoxP3+ T cells subset in tumor-draining lymph nodes of colorectal cancer secreting IL-2 and IFN-γ.

CD4+CD25-FoxP3+ cells are a newly recognized subset of T cells which was first reported in autoimmune diseases. In our previous study, this subset was detected in tumor-draining lymph nodes (TDLNs) of patients with breast cancer. As little is known about their function in TDLNs of cancer patients, in this study, their frequency as well as their ability to produce interleukin (IL)-2, IL-10, or interferon (IFN)-γ were investigated in TDLNs of colorectal cancer (CRC) patients. Mononuclear cells were isolated from lymph nodes of 13 patients with CRC using Ficoll-Hypaque gradient centrifugation. Cells were stimulated in vitro and stained with CD25, CD4, FoxP3, IFN-γ, IL-10, and IL-2 or isotype matched antibodies and subjected to flow cytometry. The frequency of CD4+CD25-FoxP3+CD127dim/- cells was significantly lower than CD4+CD25+FoxP3+CD127dim/- population in TDLNs of CRC patients. The percentage of CD127dim/- cells and also the MFI of FoxP3 expression was significantly lower in CD4+CD25-FoxP3+ in comparison with CD4+CD25+FoxP3+ population. Moreover, CD4+CD25-FoxP3+ cells contained higher percentages of IL-2- and IFN-γ-producing cells than CD4+CD25+FoxP3+ subpopulation. But, no difference was seen between two subsets in terms of IL-10 production. CD4+CD25-FoxP3+ cells in TDLNs of CRC patients had lower suppressive and higher effector properties in comparison with CD4+CD25+FoxP3+ conventional regulatory T cells.

Abstract 3206: Programmed death receptor-1/programmed death receptor ligand-1 blockade improves priming of antitumor effector T cells after cytotoxic therapies

Abstract Cytotoxic lymphodepletion therapies, such as chemotherapy and radiotherapy, have been established to augment antitumor immunity. Naïve T cells elicit effector-like phenotypes and functions during recovery from lymphopenia. We and others have repeatedly demonstrated that transfer of naïve T cells into lymphopenic-tumor bearing mice delayed tumor growth. This enhancement of naïve T cells is required an activation through T-cell receptor (TCR). Programmed death receptor-1 (PD-1)/programmed death receptor ligand-1 (PD-L1) blockade therapy has been demonstrated to augment antitumor immunity. Previous studies have shown that PD-1/PD-L1 blockade therapy stimulates or restores the function of antitumor T cells in the effector phase. Because engagement of programmed death receptor-1 (PD-1) by ligand suppresses TCR signaling and inhibits T cell activation and function, there is a possibility that PD-1 regulates activation of T cells during recovery from lymphopenia after cytotoxic therapies. In the current study, we transferred naïve T cells into tumor-bearing mice following whole-body irradiation for lymphodepletion. These mice were further treated with anti-PD-1 antibodies. PD-1/PD-L1 blockade therapy after lymphodepletion significantly suppressed tumor progression. Next, we tested several kinds of cytotoxic agents to induce lymphopenia in mice. We found that the kind of cytotoxic agents affected the augmentation of antitumor efficacies of PD-1/PD-L1 blockade. Analyses of tumor-draining lymph-nodes (TDLNs) revealed that the number of tumor-specific effector T cells was significantly increased in mice treated with anti-PD-1 antibodies. By contrast, the number of effector T cells in spleens was not increased by PD-1/PD-L1 blockade therapy. These results indicate that PD-1 regulates a priming of antitumor effector T cells in TDLNs after cytotoxic lymphodepletion therapies. PD-1/PD-L1 blockade therapy is able to enhance antitumor T cell responses not only in the effector phase but also in the priming phase. Citation Format: Miho Takahashi, Satoshi Watanabe, Ko Sato, Tomohiro Tanaka, Yu Saida, Junko Baba, Aya Ohtsubo, Miyuki Sato, Rie Kondo, Masaaki Okajima, Junta Tanaka, Hiroshi Kagamu, Hirohisa Yoshizawa, Toshiaki Kikuchi. Programmed death receptor-1/programmed death receptor ligand-1 blockade improves priming of antitumor effector T cells after cytotoxic therapies. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3206.

CD169 identifies an activated CD8+ T cell subset in regional lymph nodes that predicts favorable prognosis in colorectal cancer patients

ABSTRACTPurpose: CD169 was first identified on macrophages (Mφ) and linked to antigen presentation. Here, we showed CD169 expression on some CD8+ T lymphocytes in regional lymph nodes (LNs) and investigated the function and clinical relevance of CD169+CD8+ T cells in tumor-draining LNs of colorectal cancer (CRC) patients. Experimental design: Fresh tumor-draining LN tissues from 39 randomly enrolled patients were assessed by flow cytometry for activation and differentiation of CD169+CD8+ T cells and T cell-mediated killing of tumor cells. In total, 114 tumor-draining LN paraffin sections from CRC patients were analyzed by multiple-color immunofluorescence for CD169+CD8+ T cell distribution and clinical values. The prognostic significance of CD169+CD8+ T cells was evaluated by Kaplan–Meier analysis. Results: A fraction of CD8+ T cells in regional LNs, but not peripheral blood, tonsils, or tumors, expressed surface CD169. In situ detection of draining LNs revealed preferential localization of CD169+CD8+ T cells to subcapsular sinus and interfollicular regions, closely associated with CD169+ Mφ. CD169+CD8+ T cell ratios were significantly lower in peri-tumor LNs than distant-tumor LNs. CD169+CD8+ T cells predominantly expressed activation markers (CD69, HLA-DR, PD-1) with slightly lower CD45RA and CD62L levels. They produced high granzyme B, perforin, TNF-α, and IFNγ levels, and promoted tumor-killing efficiency ex vitro. Moreover, CD169+CD8+ T cells infiltrating tumor-draining LNs decreased with disease progression and were strongly associated with CRC patient survival. Conclusions: We identified novel activated/cytolytic CD169+CD8+ T cells selectively present in regional LNs, potentially serving as a powerful prognostic factor and indicator for selecting patients for immunotherapy.

Alteration of CD4 T cell subsets in metastatic lymph nodes of human gastric cancer.

Studies of tumor-infiltrating immune cells have revealed that immune escape plays an important role in tumor growth. The aim of the present study was to investigate the impact of metastasis affecting CD4+ T cell subsets in human clinical samples. Single-cell suspensions derived from tumor-draining lymph node (TDLN) and primary cancer specimens were assessed by flow cytometry, qRT-PCR and immunohistochemistry. In the CD4+ T cell subsets detected in TDLN, effector T cells (TE) in metastatic TDLN (mTDLN) was significantly lower than that in metastatic-free TDLN (mfTDLN). TE in mfTDLN were increased compared with normal controls. Similarly, effector memory T cells (TEM) in mTDLN was significantly lower than in control and mfTDLN. There was a significantly positive correlation between the proportion of TEM in TDLN and number of tumor-infiltrating CD4+ and CD8+ T cells. Th1 to Th2 ratio was lower in mTDLN, and Treg in mTDLN was significantly higher than in mfTDLN. CD4+ T cell and TE subsets in TDLN were significantly affected by metastasis. Immunosuppressive cells exhibit increased migration to TDLN, in which a subset of CD4+ TE is skewed towards immune tolerance in the tumor microenvironment.

Circulating CD14(+)HLA-DR(-/low) myeloid-derived suppressor cell is an indicator of poor prognosis in patients with ESCC.

Accumulating evidences demonstrate that a population of suppressive cells known as myeloid-derived suppressor cells (MDSCs) is key immune modulators which suppress antitumor immunity. In this study, we found that the level of circulating CD14(+)HLA-DR(-/low) cells in patients was significantly higher than that of healthy donors and was correlated with tumor burden, lymph node metastasis, and tumor, node, and metastasis (TNM) clinical stage. More importantly, we for the first time find the level of CD14(+)HLA-DR(-/low) is a biological indicator of poor prognosis through the analysis of 3-year overall survival. Furthermore, we evidenced that the proportion of CD14(+)HLA-DR(-/low) cells in the tumor metastatic tumor-draining lymph nodes (TDLNs) was notably higher compared to tumor-free TDLNs. Additionally, CD14(+)HLA-DR(-/low) cells from esophageal squamous cell carcinoma (ESCC) patients expressed dramatically increased programmed death ligand 1 (PD-L1) comparing to that from healthy control. Subsequently, blocking PD-L1 pathway by antibody could effectively reverse the suppressive effect on autologous T cell proliferation mediated by CD14(+)HLA-DR(-/low) cells in vitro. In conclusion, our data revealed CD14(+)HLA-DR(-/low) MDSCs which increase in ESCC patients is a novel poor prognostic indicator and may exert immunosuppressive properties through PD-L1/PD-1 pathway.

Mesothelioma tumor cells modulate dendritic cell lipid content, phenotype and function.

Dendritic cells (DCs) play an important role in the generation of anti-cancer immune responses, however there is evidence that DCs in cancer patients are dysfunctional. Lipid accumulation driven by tumor-derived factors has recently been shown to contribute to DC dysfunction in several human cancers, but has not yet been examined in mesothelioma. This study investigated if mesothelioma tumor cells and/or their secreted factors promote increases in DC lipid content and modulate DC function. Human monocyte-derived DCs (MoDCs) were exposed to human mesothelioma tumor cells and tumor-derived factors in the presence or absence of lipoproteins. The data showed that immature MoDCs exposed to mesothelioma cells or factors contained increased lipid levels relative to control DCs. Lipid accumulation was associated with reduced antigen processing ability (measured using a DQ OVA assay), upregulation of the co-stimulatory molecule, CD86, and production of the tolerogenic cytokine, IL-10. Increases in DC lipid content were further enhanced by co-exposure to mesothelioma-derived factors and triglyceride-rich lipoproteins, but not low-density lipoproteins. In vivo studies using a murine mesothelioma model showed that the lipid content of tumor-infiltrating CD4+CD8α- DCs, CD4-CD8α- DCs DCs and plasmacytoid DCs increased with tumor progression. Moreover, increasing tumor burden was associated with reduced proliferation of tumor-antigen-specific CD8+ T cells in tumor-draining lymph nodes. This study shows that mesothelioma promotes DC lipid acquisition, which is associated with altered activation status and reduced capacity to process and present antigens, which may impair the ability of DCs to generate effective anti mesothelioma T cell responses.

Cryo-ablation improves anti-tumor immunity through recovering tumor educated dendritic cells in tumor-draining lymph nodes.

BackgroundIn addition to minimally invasive destruction of tumors, cryo-ablation of tumors to some extent modulated anti-tumor immunity. Cryo-ablated tumors in glioma mice models induced anti-tumor cellular immunologic response which increases the percentage of CD3+ and CD4+T cells in blood as well as natural killer cells. As a crucial role in triggering anti-tumor immunity, dendritic cells (DCs) were educated by tumors to adopt a tolerance phenotype which helps the tumor escape from immune monitoring. This study aims to study whether cryo-ablation could influence the tolerogenic DCs, and influence anti-tumor immunity in tumor-draining lymph nodes (TDLNs).MethodsUsing the GL261 subcutaneous glioma mouse model, we created a tumor bearing group, cryo-ablation group, and surgery group. We analyzed alteration in phenotype and function of tolerogenic DCs, and evaluated the factors of anti-tumor immunity inhibition.ResultsDCs in TDLNs in GL261 subcutaneous glioma mouse model expressed tolerogenic phenotype. In contrast to surgery, cryo-ablation improved the quantity and quality of these tolerogenic DCs. Moreover, the DCs decreased the expression of intracellular interleukin-10 (IL-10) and extra-cellular IL-10. In vitro, DCs from the cryo-ablation group recovered their specific function and induced potent anti-tumor immunity through triggering T cells. In vivo, cryo-ablation showed weak anti-tumor immunity, only inhibiting the growth of rechallenged tumors. But many IL-10-low DCs, rather than IL-10-high DCs, infiltrated the tumors. More importantly, Tregs inhibited the performance of these DCs; and depletion of Tregs greatly improved anti-tumor immunity in vivo.ConclusionCryo-ablation could recover function of tumor induced tolerogenic DCs in vitro; and depletion of Tregs could improve this anti-tumor effect in vivo. The Tregs/CD4+T and Tregs/CD25+T cells in TDLNs inhibit DCs’ activity and function.

Molecular docking and dynamic simulation studies evidenced plausible immunotherapeutic anticancer property by Withaferin A targeting indoleamine 2,3-dioxygenase

Indoleamine 2,3-dioxygenase (IDO) is emerging as an important new therapeutic drug target for the treatment of cancer characterized by pathological immune suppression. IDO catalyzes the rate-limiting step of tryptophan degradation along the kynurenine pathway. Reduction in local tryptophan concentration and the production of immunomodulatory tryptophan metabolites contribute to the immunosuppressive effects of IDO. Presence of IDO on dentritic cells in tumor-draining lymph nodes leading to the activation of T cells toward forming immunosuppressive microenvironment for the survival of tumor cells has confirmed the importance of IDO as a promising novel anticancer immunotherapy drug target. On the other hand, Withaferin A (WA) – active constituent of Withania Somnifera ayurvedic herb has shown to be having a wide range of targeted anticancer properties. In the present study conducted here is an attempt to explore the potential of WA in attenuating IDO for immunotherapeutic tumor arresting activity and to elucidate the underlying mode of action in a computational approach. Our docking and molecular dynamic simulation results predict high binding affinity of the ligand to the receptor with up to −11.51 kcal/mol of energy and 3.63 nM of IC50 value. Further, de novo molecular dynamic simulations predicted stable ligand interactions with critically important residues SER167; ARG231; LYS377, and heme moiety involved in IDO’s activity. Conclusively, our results strongly suggest WA as a valuable small ligand molecule with strong binding affinity toward IDO.

Nanovaccine loaded with poly I:C and STAT3 siRNA robustly elicits anti-tumor immune responses through modulating tumor-associated dendritic cells in vivo

Although cancer vaccine-based immunotherapy holds great potential for cancer treatment, tumor-induced dendritic cell (DC) dysfunction remains to be the major obstacle for developing effective vaccines. Compared with normal DCs, tumor-associated DCs (TADCs) are less matured with poor responsiveness to Toll-like receptor (TLR) stimulation, which has been related with STAT3 hyperactivity. In the present study, Poly I:C (PIC, a TLR3 agonist), STAT3 siRNA and OVA antigen were co-encapsulated by poly (ethylene glycol)-b-poly (l-lysine)-b-poly (l-leucine) (PEG-PLL-PLLeu) polypeptide micelles to generate PMP/OVA/siRNA nanovaccine, which was aimed to effectively overcome DC dysfunction in vivo by deleting STAT3 gene in situ. The results showed that PMP/OVA/siRNA simultaneously facilitated the cellular uptake of OVA antigen and siRNA about 3–200 folds, and decreased STAT3 expression in TADCs over 50% both in vitro and in vivo. PMP/OVA/siRNA also elevated CD86 and CD40 expression as well as IL-12 production by TADCs more effectively than PMP/OVA did, indicating its strong potency of inducing TADC maturation and activation. Moreover, the immunization of PMP/OVA/siRNA rather than PMP/OVA effectively abrogated immunosuppression in the tumor microenvironment by increasing mature DCs and decreasing immunosuppressive cells in tumor-draining lymph nodes, which thereby led to potent anti-tumor immune responses and dramatic tumor regression with prolonged survival. Hence, in vivo co-delivery of immunopotentiator (PIC) and immunosuppressive gene silencer (STAT3 siRNA) by nanovaccines are expected to be a promising strategy to improve the therapeutic efficacy of cancer vaccines by modulating TADCs and overcoming tumor immunosupression.

Cytotoxic T lymphocyte antigen-4 blockade enhances antitumor immunity by stimulating melanoma-specific T-cell motility.

It is now clear that anti-CTLA-4 (α-CTLA-4) antibodies stimulate tumor immunity either by relieving inhibition of effector T-cell function or by depletion of regulatory T cells (Treg). Several recent reports, however, have suggested that these antibodies may deliver a "go" signal to effector T cells, thus interrupting T-cell receptor signaling and subsequent T-cell activation. We examined the behavior of melanoma-specific CD8+ pmel-1 T cells in the B16/BL6 mouse model using intravital microscopy. Pmel-1 velocities in progressively growing tumors were lower than their velocities in tumors given a therapeutic combination that included α-CTLA-4 antibodies, suggesting that successful immunotherapy correlates with greater T-cell motility. When α-CTLA-4 antibodies were injected during imaging, the velocities of pmel-1 T cells in tumor-draining lymph nodes also increased. Because α-CTLA-4 Fab fragments had the same effect as the intact antibody, the higher T-cell motility does not seem to be due to CTLA-4 inhibitory signaling but rather to the release of nonproductive stable interactions between tumor-infiltrating T cells and tumor targets or antigen-presenting cells subsequent to CTLA-4 blockade. This phenomenon resembles the recently described reversal of the antiviral T-cell motility paralysis by programmed death 1 (PD-1)-specific antibodies during T-cell exhaustion in persistent viral infections.

A commercially available preparation of Staphylococcus aureus bio-products potently inhibits tumour growth in a murine model of mesothelioma.

Mesothelioma is an incurable cancer with a rising global incidence. Intrapleural delivery of a commercially available compound made up of proteins produced by Staphylococcus aureus has been used clinically to induce pleurodesis. We investigate if this bacterial compound has anti-tumoural activities against pleural malignancies, in addition to its pleurodesing effect. The effects of the treatment on mesothelioma cells were evaluated in vitro and further tested in two validated murine models. This S. aureus bio-product mixture effectively kills mesothelioma cells and induces the release of interleukin (IL)-8, monocyte chemotactic protein (MCP)-1 and vascular endothelial growth factor from primary human mesothelial cells but not malignant pleural mesothelioma cells in vitro. Intratumoural delivery of the treatment in BALB/c mice induced tumour necrosis and local activation of T cells. Tumour growth was significantly inhibited in the treatment group during and after the treatment period (size of tumour 58.8 ± 10.3 mm(2) vs 118.3 ± 6.7 mm(2) from saline controls at day 23, n = 9-12 per group), P < 0.001. Tumour growth resumed on cessation of treatment, confirming the inhibition was treatment related. Treatment benefits were further validated in an orthotopic peritoneal model of mesothelioma and the compound significantly reduced the mesothelioma load (P < 0.05 vs saline controls). Mice in the treatment group had a significant increase in the percentage of activated CD4(+) and CD8(+) T cells in tumour-draining lymph nodes. No histological side-effects were observed with the treatment. This proof-of-principle study demonstrates promising antitumoural activity of a commercially available compound of S. aureus bio-products against mesothelioma.

PD-1(+) CD8(+) T cells are exhausted in tumours and functional in draining lymph nodes of colorectal cancer patients.

Background:The blockade of PD-1–PD-L1 pathway is emerging as an effective therapeutic strategy for several advanced cancers. But the immune regulatory role of PD-1–PD-L1 pathway is not clear in colorectal cancer (CRC) patients. This study aims to evaluate the role of PD-1–PD-L1 pathway in CD8+ T-cell functions in tumour-draining lymph nodes (TDLNs) and tumours of CRC patients.Methods:PD-1 expression on CD8+ T cells was examined by flow cytometry, and PD-L1 expression in TDLNs and tumour tissues were examined by immunohistochemistry. Production of IFN-γ, IL-2 and expression of granzyme B, perforin in CD8+ T cells were detected by intracellular staining.Results:PD-1 expression is markedly upregulated on CD8+ T cells in TDLNs and tumours compared with that in peripheral blood. PD-1-expressing CD8+ T cells are competent for production of cytokine (IL-2 and IFN-γ) and perforin in the tumour-free lymph nodes (TFLNs), but exhibit exhausted phenotypes in tumours. In addition, PD-L1 is highly expressed in tumours rather than TFLNs, which is closely correlated with the impairment of IFN-γ production of tumour-infiltrating PD-1+ CD8+ T cells.Conclusions:Our findings suggest a suppressive effect of PD-1 on CD8+ T-cell function in tumours, but not in TFLNs.