Increased numbers of monocyte-derived dendritic cells during successful tumor immunotherapy with immune-activating agents

Associations between serum uric acid and breast cancer incidence: A systematic review and meta-analysis

BACKGROUND

Serum uric acid (SUA) may be involved in the development of cancer by inhibiting oxidative stress, but its relationship with breast cancer remains unclear.

METHODS

The PubMed, Embase, and Web of Science databases were searched systematically for studies on SUA levels in women with breast cancer and the effect of SUA levels on the risk of breast cancer. The Newcastle‒Ottawa Quality Assessment Scale (NOS) was used to assess the quality of all relevant studies included.

RESULTS

A total of 19 studies were included, including 75,827 women with breast cancer and 508,528 healthy controls. A meta-analysis found that SUA levels were negatively correlated with breast cancer risk in women (HR = 0.94, 95% CI: 0.89 - 0.99, p = 0.003). SUA levels in female breast cancer patients were not significantly different from those in healthy controls (SMD = 0.49, 95% CI = -0.09 - 1.08, p = 0.10), while SUA levels were increased in female breast cancer patients in articles published after 2010, SUA concentration detected by spectrophotometry, and non-Asian populations, regardless of menopausal state and treatment state.

CONCLUSION

High levels of SUA may reduce the risk of breast cancer in women, suggesting that SUA was a protective factor in women.

Dendritic cells in liver transplantation immune response

Dendritic cells (DCs) are the most powerful antigen presenting cells (APCs), they are considered one of the key regulatory factors in the liver immune system. There is currently much interest in modulating DC function to improve transplant immune response. In liver transplantation, DCs participate in both the promotion and inhibition of the alloreponse by adopting different phenotypes and function. Thus, in this review, we discussed the origin, maturation, migration and pathological effects of several DC subsets, including the conventional DC (cDC), plasmacytoid DC (pDC) and monocyte-derived DC (Mo-DC) in liver transplantation, and we summarized the roles of these DC subsets in liver transplant rejection and tolerance. In addition, we also outlined the latest progress in DC-based related treatment regimens. Overall, our discussion provides a beneficial resource for better understanding the biology of DCs and their manipulation to improve the immune adaptability of patients in transplant status.

Bacteria-based immunotherapy for cancer: a systematic review of preclinical studies

Immunotherapy has been emerging as a powerful strategy for cancer management. Recently, accumulating evidence has demonstrated that bacteria-based immunotherapy including naive bacteria, bacterial components, and bacterial derivatives, can modulate immune response via various cellular and molecular pathways. The key mechanisms of bacterial antitumor immunity include inducing immune cells to kill tumor cells directly or reverse the immunosuppressive microenvironment. Currently, bacterial antigens synthesized as vaccine candidates by bioengineering technology are novel antitumor immunotherapy. Especially the combination therapy of bacterial vaccine with conventional therapies may further achieve enhanced therapeutic benefits against cancers. However, the clinical translation of bacteria-based immunotherapy is limited for biosafety concerns and non-uniform production standards. In this review, we aim to summarize immunotherapy strategies based on advanced bacterial therapeutics and discuss their potential for cancer management, we will also propose approaches for optimizing bacteria-based immunotherapy for facilitating clinical translation.

Immune profiling identifies CD8+ T-cell subset signatures as prognostic markers for recurrence in papillary thyroid cancer

Background

Thyroid tissue has a special immune microenvironment that is not well characterized. Whether immune cells have a prognostic value in the recurrence of papillary thyroid cancer (PTC) needs further investigation.

Methods

Multinodular non-toxic goiter (MNG) was taken as normal tissue for the difficulty in obtaining completely normal thyroid tissue (normal thyroid function, no thyroiditis, and no nodules). We compared the composition of mononuclear cells (MNCs) in peripheral blood and thyroid tissues from MNG and PTC patients by high-dimensional flow cytometry profiling and verified the results by multiplex immunohistochemistry. The recurrence rates of PTC patients with different CD8⁺T cell subset signatures were compared using TCGA database.

Results

We observed that the immune cell composition of MNG was different from that in peripheral blood. Thyroid tissue contains higher percentages of T cells and NK cells. Moreover, the percentages of memory T cells and Treg cells were higher in thyroid than in peripheral blood and increased in PTC tumors. We further focused on the antitumoral CD8⁺T cells and found that the expression patterns of PD-1, CD39, and CD103 on CD8⁺T cells were different between MNG and PTC. Importantly, we found higher percentages of PD-1⁺CD39⁺CD103⁺CD8⁺T and PD-1⁺CD39⁺CD103^-CD8⁺T cells in PTC tumor tissues from recurrent patients than non-recurrent patients. By analyzing PTC data from TCGA database, we found that the expression patterns of these molecules were associated with different pathologic types and genders among PTC patients. Moreover, patients with PD-1^hiCD39^loCD103^hiCD8^hi, PD-1^hiCD39^hiCD103^loCD8^hi, and PD-1^loCD39^hiCD103^hiCD8^hi expression patterns have a higher 10-year recurrence-free survival.

Conclusion

The immune microenvironment in MNG tissue is distinct from that in peripheral blood and paratumor tissue. More memory CD8⁺T cells were detected in PTC, and expression patterns of PD-1, CD39, and CD103 on CD8⁺T cells were significantly different in physiology and gender and associated with the recurrence rate of PTC. These observations indicate that CD8⁺T cell signatures may be useful prognostic markers for PTC recurrence.

Effect of BCG HSP70 Gene Transfection on Dendritic Cells Derived From Bone Marrow in Children With Acute Leukemia

OBJECTIVES

In this study, immature dendritic cells (imDCs) were transfected with the Bacillé Calmette-Guérin (BCG) heat shock protein 70 (HSP70) gene to investigate the impact on the maturity and function of imDCs from the bone marrow of pediatric patients with acute leukemia.

MATERIALS AND METHODS

Bone marrow mononuclear cells were isolated from pediatric patients with acute lymphoblastic leukemia who had achieved complete remission at least 6 months prior. The recombinant vector pDisplay-HSP70 was transfected into imDCs. The test groups included 5 subgroups: imDCs (imDCs without special processing), imDC-neos (imDCs transfected with the pDisplay vector), HSP70 (imDCs transfected with the pDisplay-HSP70 vector), tumor necrosis factor α (TNF-α) (imDCs induced with rhTNF-α), and HSP70+TNF-α. Mature dendritic cells (mDCs) from different groups (HSP70, TNF-α, and HSP70+TNF-α) and T cells were cultured. An equal number of lymphocytes and mDCs were used as controls. The proliferation indices of T cells and the cytokine contents (interleukin-12 and interferon-γ) were determined.

RESULTS

The HSP70 group and the TNF-α group expressed higher levels of HLA-DR, CD80, and CD86 but lower levels than the HSP70+TNF-α group; there was no significant difference between the HSP70 group and the TNF-α group. The combination of HSP70 and TNF-α induced the highest levels of interleukin-12 and interferon-γ.

CONCLUSIONS

The outcomes of this study indicated that gene transfection with BCG HSP70 evidently promoted imDC maturity and the antitumor effects of mDC-mediated T cells. It could serve as a candidate gene-modified cell vaccine for tumor immunotherapy.

Gold Glyconanoparticles Combined with 91–99 Peptide of the Bacterial Toxin, Listeriolysin O, Are Efficient Immunotherapies in Experimental Bladder Tumors

Simple Summary

We propose a novel type of immunotherapy for bladder cancer using gold nanoparticles bound to a peptide of a bacterial toxin with anti-tumor capacities as listeriolysin O called Listeria nanovaccines. Here, we present the pre-clinical experiments on a mice model of bladder cancer and blood cells of patients with bladder cancer using these Listeria nanovaccines that activate the immune system, block the tumor immunosuppression environment, and reduce the tumor size. The impact of Listeria nanovaccines on the field of immunotherapies for solid tumors can be extended to other solid tumors containing lymphocyte infiltration. Therefore, we propose Listeria nanovaccines as immunotherapy for tumors such as melanoma, urothelial bladder carcinoma, non-small cell lung carcinoma, and glioblastoma.

Abstract

This study presents proof of concept assays to validate gold nanoparticles loaded with the bacterial peptide 91–99 of the listeriolysin O toxin (GNP-LLO_91–99 nanovaccines) as immunotherapy for bladder tumors. GNP-LLO_91–99 nanovaccines showed adjuvant abilities as they induce maturation and activation of monocyte-derived dendritic cells (MoDCs) to functional antigen-presenting cells in healthy donors and patients with melanoma or bladder cancer (BC), promoting a Th1 cytokine pattern. GNP-LLO_91–99 nanovaccines were also efficient dendritic cell inducers of immunogenic tumor death using different bladder and melanoma tumor cell lines. The establishment of a pre-clinical mice model of subcutaneous BC confirmed that a single dose of GNP-LLO_91–99 nanovaccines reduced tumor burden 4.7-fold and stimulated systemic Th1-type immune responses. Proof of concept assays validated GNP-LLO_91–99 nanovaccines as immunotherapy by comparison to anti-CTLA-4 or anti-PD-1 antibodies. In fact, GNP-LLO_91–99 nanovaccines increased percentages of CD4⁺ and CD8⁺ T cells, B cells, and functional antigen-presenting DCs in tumor-infiltrated lymphocytes, while they reduced the levels of myeloid-derived suppressor cells (MDSC) and suppressor T cells (T_reg). We conclude that GNP-LLO_91–99 nanovaccines can work as monotherapies or combinatory immunotherapies with anti-CTLA-4 or anti-PD-1 antibodies for solid tumors with high T cell infiltration, such as bladder cancer or melanoma.

Dual Effect of Immune Cells within Tumour Microenvironment: Pro- and Anti-Tumour Effects and Their Triggers

Our body is constantly exposed to pathogens or external threats, but with the immune response that our body can develop, we can fight off and defeat possible attacks or infections. Nevertheless, sometimes this threat comes from an internal factor. Situations such as the existence of a tumour also cause our immune system (IS) to be put on alert. Indeed, the link between immunology and cancer is evident these days, with IS being used as one of the important targets for treating cancer. Our IS is able to eliminate those abnormal or damaged cells found in our body, preventing the uncontrolled proliferation of tumour cells that can lead to cancer. However, in several cases, tumour cells can escape from the IS. It has been observed that immune cells, the extracellular matrix, blood vessels, fat cells and various molecules could support tumour growth and development. Thus, the developing tumour receives structural support, irrigation and energy, among other resources, making its survival and progression possible. All these components that accompany and help the tumour to survive and to grow are called the tumour microenvironment (TME). Given the importance of its presence in the tumour development process, this review will focus on one of the components of the TME: immune cells. Immune cells can support anti-tumour immune response protecting us against tumour cells; nevertheless, they can also behave as pro-tumoural cells, thus promoting tumour progression and survival. In this review, the anti-tumour and pro-tumour immunity of several immune cells will be discussed. In addition, the TME influence on this dual effect will be also analysed.

Effects of Mycobacterium bovis Calmette et Guérin (BCG) in oncotherapy: Bladder cancer and beyond

The Mycobacterium bovis Bacillus Calmette et Guérin (BCG) vaccine was generated in 1921 with the efforts of a team of investigators, Albert Calmette and Camille Guérin, dedicated to the determination to develop a vaccine against active tuberculosis (TB) disease. Since then, BCG vaccination is used globally for protection against childhood and disseminated TB; however, its efficacy at protecting against pulmonary TB in adult and aging populations is highly variable. Due to the BCG generated immunity, this vaccine later proved to have an antitumor activity; though the standing mechanisms behind are still unclear. Recent studies indicate that both innate and adaptive cell responses may play an important role in BCG eradication and prevention of bladder cancer. Thus, cells such as natural killer (NK) cells, macrophages, dendritic cells, neutrophils but also MHC-restricted CD4 and CD8 T cells and γδ T cells may play an important role and can be one the main effectors in BCG therapy. Here, we discuss the role of BCG therapy in bladder cancer and other cancers, including current strategies and their impact on the generation and sustainability of protective antitumor immunity against bladder cancer.

Insights Into Dendritic Cells in Cancer Immunotherapy: From Bench to Clinical Applications

Dendritic cells (DCs) are efficient antigen-presenting cells (APCs) and potent activators of naïve T cells. Therefore, they act as a connective ring between innate and adaptive immunity. DC subsets are heterogeneous in their ontogeny and functions. They have proven to potentially take up and process tumor-associated antigens (TAAs). In this regard, researchers have developed strategies such as genetically engineered or TAA-pulsed DC vaccines; these manipulated DCs have shown significant outcomes in clinical and preclinical models. Here, we review DC classification and address how DCs are skewed into an immunosuppressive phenotype in cancer patients. Additionally, we present the advancements in DCs as a platform for cancer immunotherapy, emphasizing the technologies used for in vivo targeting of endogenous DCs, ex vivo generated vaccines from peripheral blood monocytes, and induced pluripotent stem cell-derived DCs (iPSC-DCs) to boost antitumoral immunity.

Interleukin-1 as Innate Mediator of T Cell Immunity

The three-signal paradigm tries to capture how the innate immune system instructs adaptive immune responses in three well-defined actions: (1) presentation of antigenic peptides in the context of MHC molecules, which allows for a specific T cell response; (2) T cell co-stimulation, which breaks T cell tolerance; and (3) secretion of polarizing cytokines in the priming environment, thereby specializing T cell immunity. The three-signal model provides an empirical framework for innate instruction of adaptive immunity, but mainly discusses STAT-dependent cytokines in T cell activation and differentiation, while the multi-faceted roles of type I IFNs and IL-1 cytokine superfamily members are often neglected. IL-1α and IL-1β are pro-inflammatory cytokines, produced following damage to the host (release of DAMPs) or upon innate recognition of PAMPs. IL-1 activity on both DCs and T cells can further shape the adaptive immune response with variable outcomes. IL-1 signaling in DCs promotes their ability to induce T cell activation, but also direct action of IL-1 on both CD4+ and CD8+ T cells, either alone or in synergy with prototypical polarizing cytokines, influences T cell differentiation under different conditions. The activities of IL-1 form a direct bridge between innate and adaptive immunity and could therefore be clinically translatable in the context of prophylactic and therapeutic strategies to empower the formation of T cell immunity. Understanding the modalities of IL-1 activity during T cell activation thus could hold major implications for rational development of the next generation of vaccine adjuvants.

Efficient gene knockout in primary human and murine myeloid cells by non-viral delivery of CRISPR-Cas9

Myeloid cells play critical and diverse roles in mammalian physiology, including tissue development and repair, innate defense against pathogens, and generation of adaptive immunity. As cells that show prolonged recruitment to sites of injury or pathology, myeloid cells represent therapeutic targets for a broad range of diseases. However, few approaches have been developed for gene editing of these cell types, likely owing to their sensitivity to foreign genetic material or virus-based manipulation. Here we describe optimized strategies for gene disruption in primary myeloid cells of human and murine origin. Using nucleofection-based delivery of Cas9-ribonuclear proteins (RNPs), we achieved near population-level genetic knockout of single and multiple targets in a range of cell types without selection or enrichment. Importantly, we show that cellular fitness and response to immunological stimuli is not significantly impacted by the gene editing process. This provides a significant advance in the study of myeloid cell biology, thus enabling pathway discovery and drug target validation across species in the field of innate immunity.

Mycobacteria-Based Vaccines as Immunotherapy for Non-urological Cancers

The arsenal against different types of cancers has increased impressively in the last decade. The detailed knowledge of the tumor microenvironment enables it to be manipulated in order to help the immune system fight against tumor cells by using specific checkpoint inhibitors, cell-based treatments, targeted antibodies, and immune stimulants. In fact, it is widely known that the first immunotherapeutic tools as immune stimulants for cancer treatment were bacteria and still are; specifically, the use of Mycobacterium bovis bacillus Calmette-Guérin (BCG) continues to be the treatment of choice for preventing cancer recurrence and progression in non-invasive bladder cancer. BCG and also other mycobacteria or their components are currently under study for the immunotherapeutic treatment of different malignancies. This review focuses on the preclinical and clinical assays using mycobacteria to treat non-urological cancers, providing a wide knowledge of the beneficial applications of these microorganisms to manipulate the tumor microenvironment aiming at tumor clearance.

Current insights into the metastasis of epithelial ovarian cancer - hopes and hurdles

BACKGROUND

Ovarian cancer is the most lethal gynecologic cancer and the fifth leading cause of cancer-related mortality in women worldwide. Despite various attempts to improve the diagnosis and therapy of ovarian cancer patients, the survival rate for these patients is still dismal, mainly because most of them are diagnosed at a late stage. Up to 90% of ovarian cancers arise from neoplastic transformation of ovarian surface epithelial cells, and are usually referred to as epithelial ovarian cancer (EOC). Unlike most human cancers, which are disseminated through blood-borne metastatic routes, EOC has traditionally been thought to be disseminated through direct migration of ovarian tumor cells to the peritoneal cavity and omentum via peritoneal fluid. It has recently been shown, however, that EOC can also be disseminated through blood-borne metastatic routes, challenging previous thoughts about ovarian cancer metastasis.

CONCLUSIONS

Here, we review our current understanding of the most updated cellular and molecular mechanisms underlying EOC metastasis and discuss in more detail two main metastatic routes of EOC, i.e., transcoelomic metastasis and hematogenous metastasis. The emerging concept of blood-borne EOC metastasis has led to exploration of the significance of circulating tumor cells (CTCs) as novel and non-invasive prognostic markers in this daunting cancer. We also evaluate the role of tumor stroma, including cancer associated fibroblasts (CAFs), tumor associated macrophages (TAMs), endothelial cells, adipocytes, dendritic cells and extracellular matrix (ECM) components in EOC growth and metastasis. Lastly, we discuss therapeutic approaches for targeting EOC. Unraveling the mechanisms underlying EOC metastasis will open up avenues to the design of new therapeutic options. For instance, understanding the molecular mechanisms involved in the hematogenous metastasis of EOC, the biology of CTCs, and the detailed mechanisms through which EOC cells take advantage of stromal cells may help to find new opportunities for targeting EOC metastasis.

Melanoma-Secreted Lysosomes Trigger Monocyte-Derived Dendritic Cell Apoptosis and Limit Cancer Immunotherapy

The recent success of checkpoint blockade therapies has established immunotherapy as one of the most promising treatments for melanoma. Nonetheless, a complete curative response following immunotherapy is observed only in a fraction of patients. To identify what factors limit the efficacy of immunotherapies, we established mouse models that cease to respond to immunotherapies once their tumors exceed a certain stage. Analysis of the immune systems of the organisms revealed that the numbers of tumor-infiltrating dendritic cells (TIDC) drastically decreased with time. Further, in contrast to the current paradigm, once melanoma was established, TIDC did not migrate into sentinel lymph nodes. Instead, they underwent local cell death due to excessive phagocytosis of lysosomes. Importantly, TIDC were required to license the cytotoxic activity of tumor CD8⁺ T cells, and in their absence, T cells did not lyse melanoma cells. Our results offer a paradigm shift regarding the role of TIDC and a framework to increase the efficacy of immunotherapies. SIGNIFICANCE: This work redefines the role of monocyte-derived dendritic cells in melanoma and provides a novel strategy to increase the efficacy of T-cell-based immunotherapies in nonresponding individuals. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/10/1942/F1.large.jpg.

MSU Crystals Enhance TDB-Mediated Inflammatory Macrophage IL-1β Secretion

The tumour microenvironment predominantly consists of macrophages with phenotypes ranging from pro-inflammatory (M1-like) to anti-inflammatory (M2-like). Trehalose-6,6'-dibehenate (TDB) displays moderate anti-tumour activity and stimulates M1-like macrophages via the macrophage inducible C-type lectin (Mincle) resulting in IL-1β production. In this study, we examined if monosodium urate (MSU), a known vaccine adjuvant, can boost IL-1β production by TDB-stimulated macrophages. We investigated the effect of MSU/TDB co-treatment on IL-1β production by GM-CSF (M1-like) and M-CSF/IL-4 (M2-like) differentiated mouse bone marrow macrophages (BMMs) and found that MSU/TDB co-treatment of GM-CSF BMMs significantly enhanced IL-1β production in a Mincle-dependent manner. Western blot analysis showed that increased IL-1β production by GM-CSF BMMs was associated with the induction of pro-IL-1β expression by TDB rather than MSU. Flow cytometry analysis showed that MSU/TDB co-stimulation of GM-CSF BMMs led to greater expansion of CD86^high/MHC II^high and CD86^low/MHC II^low subpopulations; however, only the latter showed increased production of IL-1β. Together, these findings provide evidence of the potential to use MSU/TDB co-treatment to boost IL-1β-mediated anti-tumour activity in M1-like tumour-associated macrophages.

Lipidic Aminoglycoside Derivatives: A New Class of Immunomodulators Inducing a Potent Innate Immune Stimulation

Development of simple and fully characterized immunomodulatory molecules is an active area of research to enhance current immunotherapies. Monophosphoryl lipid A (MPL), a nontoxic lipidic derivative from bacteria, is the first and currently only adjuvant approved in humans. However, its capacity to induce a potent response against weak immunogenic tumoral-associated antigens remains limited. Herein, a new generation of lipidic immunomodulators to conduct a structure-activity relationship study to determine the minimal structural elements conferring immunomodulatory properties is introduced. Two lead molecules characterized by a short succinyl linker between two oleyl chains and a polar headgroup consisting of either naturally occurring tobramycin (DOST) or kanamycin (DOSK) are identified. These two lipoaminoglycosides self-assemble in very small vesicles. In a wide variety of cells including 3D human cell culture, DOST and DOSK induce the upregulation of proinflammatory cytokines and interferon-inducible proteins in a dose and time-dependent manner via a caveolae-dependent proinflammatory mechanism and phosphatidylinositol phospholipase C activation. Furthermore, after intratumoral administration, these lipoaminoglycosides induce an efficient immune response leading to significant antitumor activity in a mouse breast cancer model. Altogether, these findings indicate that DOST and DOSK are two groundbreaking synthetic lipid immunostimulators that can be used as adjuvants to enhance current immunotherapeutic treatments.

Human Dendritic Cells: Their Heterogeneity and Clinical Application Potential in Cancer Immunotherapy

Dendritic cells (DC) are professional antigen presenting cells, uniquely able to induce naïve T cell activation and effector differentiation. They are, likewise, involved in the induction and maintenance of immune tolerance in homeostatic conditions. Their phenotypic and functional heterogeneity points to their great plasticity and ability to modulate, according to their microenvironment, the acquired immune response and, at the same time, makes their precise classification complex and frequently subject to reviews and improvement. This review will present general aspects of the DC physiology and classification and will address their potential and actual uses in the management of human disease, more specifically cancer, as therapeutic and monitoring tools. New combination treatments with the participation of DC will be also discussed.

Dendritic Cells and CD8 T Cell Immunity in Tumor Microenvironment

Dendritic cells (DCs) play a central role in the regulation of the balance between CD8 T cell immunity vs. tolerance to tumor antigens. Cross-priming, a process which DCs activate CD8 T cells by cross-presenting exogenous antigens, plays a critical role in generating anti-tumor CD8 T cell immunity. However, there are compelling evidences now that the tumor microenvironment (TME)-mediated suppression and modulation of tumor-infiltrated DCs (TIDCs) impair their function in initiating potent anti-tumor immunity and even promote tumor progression. Thus, DC-mediated cross-presentation of tumor antigens in tumor-bearing hosts often induces T cell tolerance instead of immunity. As tumor-induced immunosuppression remains one of the major hurdles for cancer immunotherapy, understanding how DCs regulate anti-tumor CD8 T cell immunity in particular within TME has been under intensive investigation. Recent reports on the Batf3-dependent type 1 conventional DCs (cDC1s) in anti-tumor immunity have greatly advanced our understanding on the interplay of DCs and CD8 T cells in the TME, highlighted by the critical role of CD103⁺ cDC1s in the cross-priming of tumor antigen-specific CD8 T cells. In this review, we will discuss recent advances in anti-tumor CD8 T cell cross-priming by CD103⁺ cDC1s in TME, and share perspective on future directions including therapeutic applications and memory CD8 T cell responses.

Hyperuricaemic UrahPlt2/Plt2 mice show altered T cell proliferation and defective tumor immunity after local immunotherapy with Poly I:C

Hyperuricaemia is associated with various metabolic dysfunctions including obesity, type 2 diabetes mellitus, hypertension and in general metabolic syndrome, which are all associated with increased risk of cancer. However, the direct association between elevated uricemia and cancer mortality still remains unclear. In this study, we used a mouse model of hyperuricemia, the Urah^plt2/plt2 (PLT2) mouse, to investigate the effect of high uric acid levels on anti-tumor immune responses and tumor growth. In normo-uricaemic C57BL/6 mice injected with B16 melanomas, immunotherapy by treatment with Poly I:C at the tumor site delayed tumor growth compared to PBS treatment. In contrast, Poly I:C-treated hyper-uricaemic PLT2 mice were unable to delay tumor growth. Conventional and monocyte-derived dendritic cells in the tumor-draining lymph nodes (dLN) of C57BL/6 and PLT2 mice were similarly increased after Poly I:C immunotherapy, and expressed high levels of CD40 and CD86. CD8⁺ T cells in the tumor-dLN and tumor of both WT and PLT2 mice were also increased after Poly I:C immunotherapy, and were able to secrete increased IFNγ upon in vitro restimulation. Surprisingly, tumor-specific CD8⁺ T cells in dLN were less abundant in PLT2 mice compared to C57BL/6, but showed a greater ability to proliferate even in the absence of cognate antigen. These data suggest that hyperuricaemia may affect the functionality of CD8⁺ T cells in vivo, leading to dysregulated T cell proliferation and impaired anti-tumor activity.

Clec9A+ Dendritic Cells Are Not Essential for Antitumor CD8+ T Cell Responses Induced by Poly I:C Immunotherapy

In the steady state, tumors harbor several populations of dendritic cells (DCs) and myeloid cells that are key regulators of the intratumoral immune environment. Among these cells, migratory CD103⁺ cross-presenting DCs are thought to be critical for tumor-specific CTL responses and tumor resistance. However, it is unclear whether this prominent role also extends to immunotherapy. We used a murine orthotopic mammary tumor model, as well as Clec9A-diphtheria toxin receptor mice that can be depleted of the specialized cross-presenting CD8α⁺ and CD103⁺ DC1 subsets, to investigate the role of these DCs in immunotherapy. Treatment with monosodium urate crystals and mycobacteria at the tumor site delayed tumor growth and required DC1s for efficacy. In contrast, treatment with poly I:C was equally effective regardless of DC1 depletion. Neither treatment affected myeloid-derived suppressor cell numbers in the spleen or tumor. Similar experiments using subcutaneous B16 melanoma tumors in BATF3-knockout mice confirmed that CD103⁺ DCs were not necessary for successful poly I:C immunotherapy. Nevertheless, adaptive immune responses were essential for the response to poly I:C, because mice depleted of CD8⁺ T cells or all DC subsets were unable to delay tumor growth. In vivo experiments showed that DC1 and DC2 subsets were able to take up tumor Ags, with DC2s making up the larger proportion of lymph node DCs carrying tumor material. Both DC subsets were able to cross-present OVA to OT-I T cells in vitro. Thus, immunotherapy with poly I:C enables multiple DC subsets to cross-present tumor Ag for effective antitumor immune responses.

Dendritic cells in cancer: the role revisited

Dendritic cells (DCs) with their potent antigen presenting ability are long considered as critical factor in antitumor immunity. Despite high potential in promoting antitumor responses, tumor-associated DCs are largely defective in their functional activity and can contribute to immune suppression in cancer. In recent years existence of immune suppressive regulatory DCs in tumor microenvironment was described. Monocytic myeloid derived suppressor cells (M-MDSCs) can contribute to the pool of tumor associated DCs by differentiating to inflammatory DCs (inf-DCs), which appear to have specific phenotype and is critical component of antitumor response. Here we examine the role of inf-DCs along with other DC subsets in the regulation of immune responses in cancer. These novel data expand our view on the role of DCs in cancer and may provide new targets for immunotherapy.

Clients and Oncogenic Roles of Molecular Chaperone gp96/grp94

As an endoplasmic reticulum heat shock protein (HSP) 90 paralogue, glycoprotein (gp) 96 possesses immunological properties by chaperoning antigenic peptides for activation of T cells. Genetic studies in the last decade have unveiled that gp96 is also an essential master chaperone for multiple receptors and secreting proteins including Toll-like receptors (TLRs), integrins, the Wnt coreceptor, Low Density Lipoprotein Receptor-Related Protein 6 (LRP6), the latent TGFβ docking receptor, Glycoprotein A Repetitions Predominant (GARP), Glycoprotein (GP) Ib and insulin-like growth factors (IGF). Clinically, elevated expression of gp96 in a variety of cancers correlates with the advanced stage and poor survival of cancer patients. Recent preclinical studies have also uncovered that gp96 expression is closely linked to cancer progression in multiple myeloma, hepatocellular carcinoma, breast cancer and inflammation-associated colon cancer. Thus, gp96 is an attractive therapeutic target for cancer treatment. The chaperone function of gp96 depends on its ATPase domain, which is structurally distinct from other HSP90 members, and thus favors the design of highly selective gp96-targeted inhibitors against cancer. We herein discuss the strategically important oncogenic clients of gp96 and their underlying biology. The roles of cell-intrinsic gp96 in T cell biology are also discussed, in part because it offers another opportunity of cancer therapy by manipulating levels of gp96 in T cells to enhance host immune defense.

Poly (I:C) enhances the anti-tumor activity of canine parvovirus NS1 protein by inducing a potent anti-tumor immune response

The canine parvovirus NS1 (CPV2.NS1) protein selectively induces apoptosis in the malignant cells. However, for an effective in vivo tumor treatment strategy, an oncolytic agent also needs to induce a potent anti-tumor immune response. In the present study, we used poly (I:C), a TLR3 ligand, as an adjuvant along with CPV2.NS1 to find out if the combination can enhance the oncolytic activity by inducing a potent anti-tumor immune response. The 4T1 mammary carcinoma cells were used to induce mammary tumor in Balb/c mice. The results suggested that poly (I:C), when given along with CPV2.NS1, not only significantly reduced the tumor growth but also augmented the immune response against tumor antigen(s) as indicated by the increase in blood CD4+ and CD8+ counts and infiltration of immune cells in the tumor tissue. Further, blood serum analysis of the cytokines revealed that Th1 cytokines (IFN-γ and IL-2) were significantly upregulated in the treatment group indicating activation of cell-mediated immune response. The present study reports the efficacy of CPV2.NS1 along with poly (I:C) not only in inhibiting the mammary tumor growth but also in generating an active anti-tumor immune response without any visible toxicity. The results of our study may help in developing CPV2.NS1 and poly (I: C) combination as a cancer therapeutic regime to treat various malignancies.

Monocyte-Derived Dendritic Cells Are Essential for CD8(+) T Cell Activation and Antitumor Responses After Local Immunotherapy

Tumors harbor several populations of dendritic cells (DCs) with the ability to prime tumor-specific T cells. However, these T cells mostly fail to differentiate into armed effectors and are unable to control tumor growth. We have previously shown that treatment with immunostimulatory agents at the tumor site can activate antitumor immune responses and is associated with the appearance of a population of monocyte-derived DCs (moDCs) in the tumor and tumor-draining lymph node (dLN). Here, we use depletion of DCs or monocytes and monocyte transfer to show that these moDCs are critical to the activation of antitumor immune responses. Treatment with the immunostimulatory agents monosodium urate crystals and Mycobacterium smegmatis induced the accumulation of monocytes in the dLN, their upregulation of CD11c and MHCII, and expression of iNOS, TNFα, and IL12p40. Blocking monocyte entry into the lymph node and tumor through neutralization of the chemokine CCL2 or inhibition of colony-stimulating factor-1 receptor signaling prevented the generation of moDCs, the infiltration of tumor-specific T cells into the tumor, and antitumor responses. In a reciprocal fashion, monocytes transferred into mice depleted of CD11c(+) cells were sufficient to rescue CD8(+) T cell priming in lymph node and delay tumor growth. Thus, monocytes exposed to the appropriate conditions become powerful activators of tumor-specific CD8(+) T cells and antitumor immunity.

The role of chemotherapy and operation on lymphocytes accumulation in peripheral blood obtained from patients with oral squamous cell carcinoma

The "Cancer Immunoediting" concept has provided critical insights suggesting dual functions of immune system during the cancer initiation and development. However, the dynamics and roles of CD4(+) and CD8(+) T cells, CD19(+) B cells, and CD56(+) NK cells in the patients with oral squamous cell carcinoma during treatment remain unclear. A total of 43 patients with OSCC were divided into different groups according to different clinical factors (TNM staging, pathological patterns, age and genders) for assessment of relations with CD3(+)CD4(+) T cells, CD3(+)CD8(+) T cells, CD3(-)CD19(+) B cells and CD3(-)CD16(+)CD56(+) NK cells and different chemotherapy and radical operation. The expression of CD3(+)CD4(+) T cells were significantly increased in advanced tumor stage, large tumor size and positive lymph nodes metastasis, compared to that in early groups. The accumulation of CD3(+)CD4(+) T cells were significantly increased in OSCC patients received 2 cycles CT and radical operation. Moreover, the accumulation of CD3(+)CD8(+) T cells were significantly decreased in OSCC patients received 2 cycles CT and radical operation. The distribution of circulating CD3(-)CD19(+) B cells was related with radical operation in patients with OSCC. This study indicate that CD4(+) T cells have opposing roles in OSCC progression and outcomes, which provides new insights relevant for the development of effective cancer immunotherapeutic approaches. 2 cycles TP regime chemotherapy and radical therapy may contribute to increase the effects of anti-tumor immunity on patients with OSCC.

Uric acid enhances the antitumor immunity of dendritic cell-based vaccine

Uric acid (UA) released from dying cells has been recognized by the immune system as a danger signal. In response to UA, dendritic cells (DC) in the immune system mature and enhance the T cell response to foreign antigens. It is conceivable that the antitumor immunity of a tumor vaccine could be promoted by the administration of UA. To test this concept, we applied UA as an adjuvant to a DC-based vaccine, and discovered that the administration of UA as an adjuvant significantly enhanced the ability of the tumor lysate-pulsed DC vaccine in delaying the tumor growth. The antitumor activity was achieved with adoptively transferred lymphocytes, and both CD8⁺ T cells and NK cells were required to achieve effective immunity. This resulted in an increased accumulation of activated CD8⁺ T cells and an elevated production of IFN-γ. Collectively, our study shows that the administration of UA enhances the antitumor activity of tumor lysate-pulsed DC vaccine, thus providing the preclinical rationale for the application of UA in DC-based vaccine strategies.

Repeated fine-needle aspiration of solid tumours in mice allows the identification of multiple infiltrating immune cell types

This paper describes a novel method for following the changes in mouse tumour-infiltrating immune cell populations by repeated sampling of tumours by fine needle aspiration (FNA), followed by flow cytometry. Using this technique we were able to collect samples from P815 mouse mastocytomas, and identify and enumerate six tumour-infiltrating immune cell types at multiple time points for each mouse. We demonstrate good agreement between cell percentages obtained from FNA samples and matched whole tumour digests (WTDs). We also demonstrate that neither survival nor the incidence of liver metastasis is adversely affected by the procedure. Our method has a clear advantage over the common practice of sacrificing mice and collecting tissue at pre-determined time points, as the technique allows 1) repeated sampling of each mouse over time, thus many fewer mice are required, and 2) the correlation of survival data with tumour-infiltrating immune cell types at different time points. This potentially allows immune cell types associated with increased or decreased survival to be identified. Therefore, our technique should greatly facilitate the characterisation of anti-tumour immunity induced in response to cancer therapy in small animal models.

IL-1βR-dependent priming of antitumor CD4+ T cells and sustained antitumor immunity after peri-tumoral treatment with MSU and mycobacteria

Local immune-activating therapies seek to improve the presentation of tumor antigen, thereby promoting the activation of antitumor CD8⁺ T cells and delaying tumor growth. Surprisingly, little is known about the ability of these therapies to stimulate antitumor CD4⁺ T cells. We examined tumor-specific CD4⁺ T cell responses after peri-tumoral administration of the TLR3 agonist polyinosinic-polycytidylic acid (poly I:C), or the danger signal monosodium urate crystals in combination with Mycobacterium smegmatis (MSU + Msmeg) in mice. Both treatments delayed tumor growth, however, only MSU + Msmeg induced proliferation of tumor-specific CD4⁺ T cells in the draining lymph node (dLN). In line with the proliferation data, administration of MSU + Msmeg, but not poly I:C, enhanced the infiltration of CD4⁺FoxP3⁻ T cells into the tumor, increased their capacity to produce IFNγ and TNF-α, and decreased PD-1 expression on tumor-infiltrating CD8⁺ T cells. Induction of CD4⁺ T cell proliferation by treatment with MSU + Msmeg required IL-1βR signaling, as it was blocked by administration of the IL-1βR antagonist Anakinra. In addition, treatment with Anakinra or with anti-CD4 also reversed the increased survival after tumor challenge in MSU + Msmeg treated mice. Thus, peri-tumoral treatment with MSU + Msmeg results in IL-1βR-dependent priming of antitumor CD4⁺ T cells in the LN, with consequent superior activation of CD4⁺ and CD8⁺ T cells within the tumor, and sustained antitumor activity.

CD3+ CD4+ and CD3+ CD8+ lymphocyte subgroups and their surface receptors NKG2D and NKG2A in patients with non-small cell lung cancer

BACKGROUND

To explore the prevalence of lymphocyte subgroups CD3+ CD4+ and CD3+ CD8+ and their surface receptors NKG2D and NKG2A in patients with non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

A total of 40 patients with NSCLC were divided into different groups according to different clinical factors (TNM staging, pathological patterns and genders) for assessment of relations with CD3+ CD4+ and CD3+ CD8+ and the surface receptors NKG2D and NKG2A of T lymphocytes in peripheral blood by flow cytometry.

RESULTS

Patients in the advanced group had evidently lower levels of CD3+ CD4+ but markedly higher levels of CD3+ CD8+ in peripheral blood than those with early lesions (p<0.05). In addition, NSCLC patients in the advanced group had obviously higher CD3+ CD4+ NKG2D and CD3+ CD8+ NKG2A expression rates but lower CD3+ CD4+ NKG2A and CD3+ CD8+ NKG2D expression rates (p<0.05). However, there were no significant differences between NSCLC patients with different genders and pathological patterns in expression levels of lymphocyte subgroups CD3+ CD4+ and CD3+ CD8+ and their surface receptors NKG2D and NKG2A.

CONCLUSIONS

Unbalanced expression of surface receptors NKG2D and NKG2A in CD3+ CD4+ and CD3+ CD8+ lymphocytes may be associated with a poor prognosis, greater malignancy and immunological evasion by advanced cancers, related to progression of lung cancer.

Tumor-infiltrating dendritic cells exhibit defective cross-presentation of tumor antigens, but is reversed by chemotherapy

Cross-presentation defines the unique capacity of an APC to present exogenous Ag via MHC class I molecules to CD8(+) T cells. DCs are specialized cross-presenting cells and as such have a critical role in antitumor immunity. DCs are routinely found within the tumor microenvironment, but their capacity for endogenous or therapeutically enhanced cross-presentation is not well characterized. In this study, we examined the tumor and lymph node DC cross-presentation of a nominal marker tumor Ag, HA, expressed by the murine mesothelioma tumor AB1-HA. We found that tumors were infiltrated by predominantly CD11b(+) DCs with a semimature phenotype that could not cross-present tumor Ag, and therefore, were unable to induce tumor-specific T-cell activation or proliferation. Although tumor-infiltrating DCs were able to take up, process, and cross-present exogenous cell-bound and soluble Ags, this was significantly impaired relative to lymph node DCs. Importantly, however, systemic chemotherapy using gemcitabine reversed the defect in Ag cross-presentation of tumor DCs. These data demonstrate that DC cross-presentation within the tumor microenvironment is defective, but can be reversed by chemotherapy. These results have important implications for anticancer therapy, particularly regarding the use of immunotherapy in conjunction with cytotoxic chemotherapy.

A critical role for natural killer cells in dendritic cell-based anticancer immunotherapy

Multipronged immunotherapies that activate both T cells and natural killer (NK) cells may result in more robust and durable anticancer responses. The successful outcome of dendritic cell (DC)-based vaccination therapy involves a hitherto unrecognized role for NK cells. Combinatorial regimens that enhance the contribution of NK cells to the anticancer immune response may therefore improve clinical outcomes.

Monocyte-derived dendritic cells: Emerging players in the antitumor immune response

The elicitation of efficient antitumor immune responses requires the optimal activation of tumor-associated dendritic cells (DCs). Our comparison of the effect of various immunostimulatory treatments on DCs revealed that the best predictor of the success of immunotherapy is not the activation of existing DC populations, but the appearance of a population of monocyte-derived DC in tumor-draining lymph nodes.