Inhibition of dendritic cell migration by transforming growth factor-β1 increases tumor-draining lymph node metastasis

Development of pharmacological immunoregulatory anti-cancer therapeutics: current mechanistic studies and clinical opportunities

Immunotherapy represented by anti-PD-(L)1 and anti-CTLA-4 inhibitors has revolutionized cancer treatment, but challenges related to resistance and toxicity still remain. Due to the advancement of immuno-oncology, an increasing number of novel immunoregulatory targets and mechanisms are being revealed, with relevant therapies promising to improve clinical immunotherapy in the foreseeable future. Therefore, comprehending the larger picture is important. In this review, we analyze and summarize the current landscape of preclinical and translational mechanistic research, drug development, and clinical trials that brought about next-generation pharmacological immunoregulatory anti-cancer agents and drug candidates beyond classical immune checkpoint inhibitors. Along with further clarification of cancer immunobiology and advances in antibody engineering, agents targeting additional inhibitory immune checkpoints, including LAG-3, TIM-3, TIGIT, CD47, and B7 family members are becoming an important part of cancer immunotherapy research and discovery, as are structurally and functionally optimized novel anti-PD-(L)1 and anti-CTLA-4 agents and agonists of co-stimulatory molecules of T cells. Exemplified by bispecific T cell engagers, newly emerging bi-specific and multi-specific antibodies targeting immunoregulatory molecules can provide considerable clinical benefits. Next-generation agents also include immune epigenetic drugs and cytokine-based therapeutics. Cell therapies, cancer vaccines, and oncolytic viruses are not covered in this review. This comprehensive review might aid in further development and the fastest possible clinical adoption of effective immuno-oncology modalities for the benefit of patients.

Dendritic Cell-Based Immunotherapy: The Importance of Dendritic Cell Migration

Dendritic cells (DCs) are specialized antigen-presenting cells that are crucial for maintaining self-tolerance, initiating immune responses against pathogens, and patrolling body compartments. Despite promising aspects, DC-based immunotherapy faces challenges that include limited availability, immune escape in tumors, immunosuppression in the tumor microenvironment, and the need for effective combination therapies. A further limitation in DC-based immunotherapy is the low population of migratory DC (around 5%-10%) that migrate to lymph nodes (LNs) through afferent lymphatics depending on the LN draining site. By increasing the population of migratory DCs, DC-based immunotherapy could enhance immunotherapeutic effects on target diseases. This paper reviews the importance of DC migration and current research progress in the context of DC-based immunotherapy.

Multiple influence of immune cells in the bone metastatic cancer microenvironment on tumors

Bone is a common organ for solid tumor metastasis. Malignant bone tumor becomes insensitive to systemic therapy after colonization, followed by poor prognosis and high relapse rate. Immune and bone cells in situ constitute a unique immune microenvironment, which plays a crucial role in the context of bone metastasis. This review firstly focuses on lymphatic cells in bone metastatic cancer, including their function in tumor dissemination, invasion, growth and possible cytotoxicity-induced eradication. Subsequently, we examine myeloid cells, namely macrophages, myeloid-derived suppressor cells, dendritic cells, and megakaryocytes, evaluating their interaction with cytotoxic T lymphocytes and contribution to bone metastasis. As important components of skeletal tissue, osteoclasts and osteoblasts derived from bone marrow stromal cells, engaging in 'vicious cycle' accelerate osteolytic bone metastasis. We also explain the concept tumor dormancy and investigate underlying role of immune microenvironment on it. Additionally, a thorough review of emerging treatments for bone metastatic malignancy in clinical research, especially immunotherapy, is presented, indicating current challenges and opportunities in research and development of bone metastasis therapies.

Lymph node and tumor-associated PD-L1+ macrophages antagonize dendritic cell vaccines by suppressing CD8+ T cells

Current immunotherapies provide limited benefits against T cell-depleted tumors, calling for therapeutic innovation. Using multi-omics integration of cancer patient data, we predict a type I interferon (IFN) responseHIGH state of dendritic cell (DC) vaccines, with efficacious clinical impact. However, preclinical DC vaccines recapitulating this state by combining immunogenic cancer cell death with induction of type I IFN responses fail to regress mouse tumors lacking T cell infiltrates. Here, in lymph nodes (LNs), instead of activating CD4+/CD8+ T cells, DCs stimulate immunosuppressive programmed death-ligand 1-positive (PD-L1+) LN-associated macrophages (LAMs). Moreover, DC vaccines also stimulate PD-L1+ tumor-associated macrophages (TAMs). This creates two anatomically distinct niches of PD-L1+ macrophages that suppress CD8+ T cells. Accordingly, a combination of PD-L1 blockade with DC vaccines achieves significant tumor regression by depleting PD-L1+ macrophages, suppressing myeloid inflammation, and de-inhibiting effector/stem-like memory T cells. Importantly, clinical DC vaccines also potentiate T cell-suppressive PD-L1+ TAMs in glioblastoma patients. We propose that a multimodal immunotherapy and vaccination regimen is mandatory to overcome T cell-depleted tumors.

Rebalancing TGF-β/PGE2 breaks RT-induced immunosuppressive barriers by enhancing tumor-infiltrated dendritic cell homing

A better understanding of how tumor microenvironments shape immune responses after radiotherapy (RT) is required to improve patient outcomes. This study focuses on the observation that dendritic cells (DCs) infiltrating irradiated cervical tumors are retained in transforming growth factor (TGF)-β-abundant regions. We report that TGF-β secretion from cervical cancer cells was increased by irradiation in a dose-dependent manner and that this significantly suppressed the expression of allostimulatory markers and Th1 cytokines in DCs. To investigate further, we blocked the TGF-β signal in DCs and observed that RT had a dose-dependent immune-promoting effect, improving DC maturation. This suggested that proinflammatory mediators may also be induced by RT, but their effects were being counteracted by the simultaneously increased levels of TGF-β. Prostaglandin E2 (PGE2), a proinflammatory molecule, was shown to be one such mediator. Adjusting the TGF-β/PGE2 ratio by inhibiting TGF-β rebooted RT-induced DC cytoskeletal organization by stimulating myosin light chain (MLC) phosphorylation. Consequently, the homing of intra-tumorally infiltrated DCs to tumor-draining lymph nodes was enhanced, leading to the induction of more robust cytotoxic T cells. Ultimately, rebalancing the TGF-β/PGE2 ratio amplified the therapeutic effects of RT, resulting in increased intra-tumoral infiltration and activation of CD8+ T cells, and improved tumor control and overall survival rate in mice. DC depletion experiments verified that the improvement in tumor control is directly correlated with the involvement of DCs via the PGE2-MLC pathway. This study emphasizes the importance of maintaining a balanced cytokine environment during RT, particularly hypofractionated RT; and it is advisable to block TGF-β while preserving PGE2 in the tumor microenvironment in order to better stimulate DC homing and DC -T priming.

TGF-β in correlation with tumor progression, immunosuppression and targeted therapy in colorectal cancer

Colorectal cancer (CRC) is a complex malignancy responsible for the second-highest cancer deaths worldwide. TGF-β maintains normal cellular homeostasis by inhibiting the cell cycle and inducing apoptosis, but its elevated level is correlated with colorectal cancer progression, as TGF-β is a master regulator of the epithelial-to-mesenchymal transition, a critical step of metastasis. Tumors, including CRC, use elevated TGF-β levels to avoid immune surveillance by modulating immune cell differentiation, proliferation, and effector function. Presently, the treatment of advanced CRC is mainly based on chemotherapy, with multiple adverse effects. Thus, there is a need to develop alternate tactics because CRC continue to be mostly resistant to the present therapeutic regimen. TGF-β blockade has emerged as a promising therapeutic target in cancer therapy. Blocking TGF-β with phytochemicals and other molecules, such as antisense oligonucleotides, monoclonal antibodies, and bifunctional traps, alone or in combination, may be a safer and more effective way to treat CRC. Furthermore, combination immunotherapy comprising TGF-β blockers and immune checkpoint inhibitors is gaining popularity because both molecules work synergistically to suppress the immune system. Here, we summarize the current understanding of TGF-β as a therapeutic target for managing CRC and its context-dependent tumor-promoting or tumor-suppressing nature.

Single-cell analysis of myeloid cells in HPV+ tonsillar cancer

The incidence of human papillomavirus-positive (HPV⁺) tonsillar cancer has been sharply rising during the last decades. Myeloid cells represent an appropriate therapeutic target due to their proximity to virus-infected tumor cells, and their ability to orchestrate antigen-specific immunity, within the tonsil. However, the interrelationship of steady-state and inflammatory myeloid cell subsets, and their impact on patient survival remains unexplored. Here, we used single-cell RNA-sequencing to map the myeloid compartment in HPV⁺ tonsillar cancer. We observed an expansion of the myeloid compartment in HPV⁺ tonsillar cancer, accompanied by interferon-induced cellular responses both in dendritic cells (DCs) and monocyte-macrophages. Our analysis unveiled the existence of four DC lineages, two macrophage polarization processes, and their sequential maturation profiles. Within the DC lineages, we described a balance shift in the frequency of progenitor and mature cDC favoring the cDC1 lineage in detriment of cDC2s. Furthermore, we observed that all DC lineages apart from DC5s matured into a common activated DC transcriptional program involving upregulation of interferon-inducible genes. In turn, the monocyte-macrophage lineage was subjected to early monocyte polarization events, which give rise to either interferon-activated or CXCL-producing macrophages, the latter enriched in advanced tumor stages. We validated the existence of most of the single-cell RNA-seq clusters using 26-plex flow cytometry, and described a positive impact of cDC1 and interferon-activated DCs and macrophages on patient survival using gene signature scoring. The current study contributes to the understanding of myeloid ontogeny and dynamics in HPV-driven tonsillar cancer, and highlights myeloid biomarkers that can be used to assess patient prognosis.

The Beneficial Effect of IL-12 and IL-18 Transduced Dendritic Cells Stimulated with Tumor Antigens on Generation of an Antitumor Response in a Mouse Colon Carcinoma Model

The main purpose of our study was to determine the effect of dendritic cell (DC) transduction with lentiviral vectors carrying sequences of il18 and/or il12 genes on the level of antitumor activity in vitro and in vivo. We examined the ability of DCs to migrate to the tumor-draining lymph nodes and infiltrate tumor tissue and to activate the local and systemic antitumor response. On the 15th day, DCs genetically modified for production of IL-12 and/or IL-18 were administered peritumorally to C57BL/6 female mice with established MC38 tumors. Lymphoid organs and tumor tissue were collected from mice on the 3rd, 5th, and 7th days after a single administration of DCs for further analysis. Administration of DCs transduced for production of IL-12 alone and in combination with IL-18 increased the inflow and activity of CD4+ and CD8+ T lymphocytes in the tumor microenvironment and tumor-draining lymph nodes. We also found that even a single administration of such modified DCs could trigger a systemic antitumor response as well as inhibit tumor growth. Application of the developed DC-based vaccines may exert a favorable impact on stimulation of an antitumor immune response, especially if these DC vaccines are administered repeatedly.

Control of Dendritic Cell Function Within the Tumour Microenvironment

The tumour microenvironment (TME) presents a major block to anti-tumour immune responses and to effective cancer immunotherapy. The inflammatory mediators such as cytokines, chemokines, growth factors and prostaglandins generated in the TME alter the phenotype and function of dendritic cells (DCs) that are critical for a successful adaptive immune response against the growing tumour. In this mini review we discuss how tumour cells and the surrounding stroma modulate DC maturation and trafficking to impact T cell function. Fibroblastic stroma and the associated extracellular matrix around tumours can also provide physical restrictions to infiltrating DCs and other leukocytes. We discuss interactions between the inflammatory TME and infiltrating immune cell function, exploring how the inflammatory TME affects generation of T cell-driven anti-tumour immunity. We discuss the open question of the relative importance of antigen-presentation site; locally within the TME versus tumour-draining lymph nodes. Addressing these questions will potentially increase immune surveillance and enhance anti-tumour immunity.

Overcoming TGFβ-mediated immune evasion in cancer

Transforming growth factor-β (TGFβ) signalling controls multiple cell fate decisions during development and tissue homeostasis; hence, dysregulation of this pathway can drive several diseases, including cancer. Here we discuss the influence that TGFβ exerts on the composition and behaviour of different cell populations present in the tumour immune microenvironment, and the context-dependent functions of this cytokine in suppressing or promoting cancer. During homeostasis, TGFβ controls inflammatory responses triggered by exposure to the outside milieu in barrier tissues. Lack of TGFβ exacerbates inflammation, leading to tissue damage and cellular transformation. In contrast, as tumours progress, they leverage TGFβ to drive an unrestrained wound-healing programme in cancer-associated fibroblasts, as well as to suppress the adaptive immune system and the innate immune system. In consonance with this key role in reprogramming the tumour microenvironment, emerging data demonstrate that TGFβ-inhibitory therapies can restore cancer immunity. Indeed, this approach can synergize with other immunotherapies - including immune checkpoint blockade - to unleash robust antitumour immune responses in preclinical cancer models. Despite initial challenges in clinical translation, these findings have sparked the development of multiple therapeutic strategies that inhibit the TGFβ pathway, many of which are currently in clinical evaluation.

The Therapeutic Potential of Tackling Tumor-Induced Dendritic Cell Dysfunction in Colorectal Cancer

Colorectal cancer (CRC) is the third most diagnosed malignancy and the second leading cause of cancer-related deaths worldwide. Locally advanced and metastatic disease exhibit resistance to therapy and are prone to recurrence. Despite significant advances in standard of care and targeted (immuno)therapies, the treatment effects in metastatic CRC patients have been modest. Untreatable cancer metastasis accounts for poor prognosis and most CRC deaths. The generation of a strong immunosuppressive tumor microenvironment (TME) by CRC constitutes a major hurdle for tumor clearance by the immune system. Dendritic cells (DCs), often impaired in the TME, play a critical role in the initiation and amplification of anti-tumor immune responses. Evidence suggests that tumor-mediated DC dysfunction is decisive for tumor growth and metastasis initiation, as well as for the success of immunotherapies. Unravelling and understanding the complex crosstalk between CRC and DCs holds promise for identifying key mechanisms involved in tumor progression and spread that can be exploited for therapy. The main goal of this review is to provide an overview of the current knowledge on the impact of CRC-driven immunosuppression on DCs phenotype and functionality, and its significance for disease progression, patient prognosis, and treatment response. Moreover, present knowledge gaps will be highlighted as promising opportunities to further understand and therapeutically target DC dysfunction in CRC. Given the complexity and heterogeneity of CRC, future research will benefit from the use of patient-derived material and the development of in vitro organoid-based co-culture systems to model and study DCs within the CRC TME.

DCision-making in tumors governs T cell anti-tumor immunity

The exploitation of T cell-based immunotherapies and immune checkpoint blockade for cancer treatment has dramatically shifted oncological treatment paradigms and broadened the horizons of cancer immunology. Dendritic cells have emerged as the critical tailors of T cell immune responses, which initiate and coordinate anti-tumor immunity. Importantly, genetic alterations in cancer cells, cytokines and chemokines produced by cancer and stromal cells, and the process of tumor microenvironmental regulation can compromise dendritic cell-T cell cross-talk, thereby disrupting anti-tumor T cell responses. This review summarizes how T cell activation is controlled by dendritic cells and how the tumor microenvironment alters dendritic cell properties in the context of the anti-tumor immune cycle. Furthermore, we will highlight therapeutic options for tailoring dendritic cell-mediated decision-making in T cells for cancer treatment.

Identification of miR-203a, mir-10a, and miR-194 as predictors for risk of lymphovascular invasion in head and neck cancers

Lymphovascular invasion (LVI) is an important prognostic indicator of lymph node metastasis and disease aggressiveness but clear molecular mechanisms mediating this in head and neck cancers (HNSC) remain undefined. To identify important microRNAs (miRNAs) in HNSC that associate with and are also predictive of increased risk of LVI, we used a combination of clustering algorithms, multiple regression analyses and machine learning approaches and analyzed miRNA expression profiles in the TCGA HNSC database. As the first step, we identified miRNAs with increased association with LVI as a binary variable. In order to determine whether the identified miRNAs would show functional clusters that are also indicative of increased risk for LVI, we carried out unsupervised as well as supervised clustering. Our results identified distinct clusters of miRNAs that are predictive of increased LVI. We further refined these findings using a Random forest approach, and miR-203a-3p, mir-10a-5p, and miR-194-5p to be most strongly associated with LVI. Pathway enrichment analysis showed these miRNAs targeted genes involved in Hippo signaling and fatty acid oxidation pathways that are mediators of lymph node metastasis. Specific association was also identified between the miRNAs associated with LVI and expression of several lymphangiogenic genes that could be critical for determination of therapeutic strategies.

Osteoimmuno-Oncology: Therapeutic Opportunities for Targeting Immune Cells in Bone Metastasis

Immunotherapies provide a potential treatment option for currently incurable bone metastases. Bone marrow is an important secondary lymphoid organ with a unique immune contexture. Even at non-disease state immune cells and bone cells interact with each other, bone cells supporting the development of immune cells and immune cells regulating bone turnover. In cancer, tumor cells interfere with this homeostatic process starting from formation of pre-metastatic niche and later supporting growth of bone metastases. In this review, we introduce a novel concept osteoimmuno-oncology (OIO), which refers to interactions between bone, immune and tumor cells in bone metastatic microenvironment. We also discuss therapeutic opportunities of targeting immune cells in bone metastases, and associated efficacy and safety concerns.

PTBP1 is necessary for dendritic cells to regulate T-cell homeostasis and antitumour immunity

Dendritic cells (DCs) play an important role in linking innate and adaptive immunity. DCs can sense endogenous and exogenous antigens and present those antigens to T cells to induce an immune response or immune tolerance. During activation, alternative splicing (AS) in DCs is dramatically changed to induce cytokine secretion and upregulation of surface marker expression. PTBP1, an RNA-binding protein, is essential in alternative splicing, but the function of PTBP1 in DCs is unknown. Here, we found that a specific deficiency of Ptbp1 in DCs could increase MHC II expression and perturb T-cell homeostasis without affecting DC development. Functionally, Ptbp1 deletion in DCs could enhance antitumour immunity and asthma exacerbation. Mechanistically, we found that Pkm alternative splicing and a subset of Ifn response genes could be regulated by PTBP1. These findings revealed the function of PTBP1 in DCs and indicated that PTBP1 might be a novel therapeutic target for antitumour treatment.

Molecular mechanisms of dendritic cell migration in immunity and cancer

Dendritic cells (DCs) are a heterogeneous population of antigen-presenting cells that act to bridge innate and adaptive immunity. DCs are critical in mounting effective immune responses to tissue damage, pathogens and cancer. Immature DCs continuously sample tissues and engulf antigens via endocytic pathways such as phagocytosis or macropinocytosis, which result in DC activation. Activated DCs undergo a maturation process by downregulating endocytosis and upregulating surface proteins controlling migration to lymphoid tissues where DC-mediated antigen presentation initiates adaptive immune responses. To traffic to lymphoid tissues, DCs must adapt their motility mechanisms to migrate within a wide variety of tissue types and cross barriers to enter lymphatics. All steps of DC migration involve cell-cell or cell-substrate interactions. This review discusses DC migration mechanisms in immunity and cancer with a focus on the role of cytoskeletal processes and cell surface proteins, including integrins, lectins and tetraspanins. Understanding the adapting molecular mechanisms controlling DC migration in immunity provides the basis for therapeutic interventions to dampen immune activation in autoimmunity, or to improve anti-tumour immune responses.

Total CD3 T Cells Are Necessary and Sufficient to Induce Colitis in Immunodeficient Mice With Dendritic Cell-Specific Deletion of TGFbR2: A Novel IBD Model to Study CD4 and CD8 T-Cell Interaction

BACKGROUND

Inflammatory bowel disease (IBD) is a multifactorial disorder, with the innate and adaptive immune cells contributing to disease initiation and progression. However, the intricate cross-talk between immune cell lineages remains incompletely understood. The role of CD8+ T cells in IBD pathogenesis has been understudied, largely due to the lack of appropriate models.

METHODS

We previously reported spontaneous colitis in mice with impaired TGFβ signaling due to dendritic cell-specific knockout of TGFbR2 (TGFβR2ΔDC). Here, we demonstrate that crossing TGFβR2ΔDC mice with a Rag1-/- background eliminates all symptoms of colitis and that adoptive transfer of unfractionated CD3+ splenocytes is sufficient to induce progressive colitis in Rag1-/-TGFβR2ΔDC mice.

RESULTS

Both CD4+ and CD8+ T cells are required for the induction of colitis accompanied by activation of both T-cell lineages and DCs, increased expression of mucosal IFNγ, TNFα, IL6, IL1β, and IL12, and decreased frequencies of CD4+FoxP3+ regulatory T cells. Development of colitis required CD40L expression in CD4+ T cells, and the disease was partially ameliorated by IFNγ neutralization.

CONCLUSIONS

This novel model provides an important tool for studying IBD pathogenesis, in particular the complex interactions among innate and adaptive immune cells in a controlled fashion, and represents a valuable tool for preclinical evaluation of novel therapeutics.

The application of nanotechnology in enhancing immunotherapy for cancer treatment: current effects and perspective

Cancer immunotherapy is emerging as a promising treatment modality that suppresses and eliminates tumors by re-activating and maintaining the tumor-immune cycle, and further enhancing the body's anti-tumor immune response. Despite the impressive therapeutic potential of immunotherapy approaches such as immune checkpoint inhibitors and tumor vaccines in pre-clinical and clinical applications, the effective response is limited by insufficient accumulation in tumor tissues and severe side-effects. Recent years have witnessed the rise of nanotechnology as a solution to improve these technical weaknesses due to its inherent biophysical properties and multifunctional modifying potential. In this review, we summarized and discussed the current status of nanoparticle-enhanced cancer immunotherapy strategies, including intensified delivery of tumor vaccines and immune adjuvants, immune checkpoint inhibitor vehicles, targeting capacity to tumor-draining lymph nodes and immune cells, triggered releasing and regulating specific tumor microenvironments, and adoptive cell therapy enhancement effects.

Impaired dendritic cell functions in lung cancer: a review of recent advances and future perspectives

Lung cancer is the leading cause of cancer mortality worldwide. Dendritic cells (DCs) are the key factors providing protective immunity against lung tumors and clinical trials have proven that DC function is reduced in lung cancer patients. It is evident that the immunoregulatory network may play a key role in the failure of the immune response to terminate tumors. Lung tumors likely employ numerous strategies to suppress DC-based anti-tumor immunity. Here, we summarize the recent advances in our understanding on lung tumor-induced immunosuppression in DCs, which affects the initiation and development of T-cell responses. We also describe which existing measures to restore DC function may be useful for clinical treatment of lung tumors. Furthering our knowledge of how lung cancer cells alter DC function to generate a tumor-supportive environment will be essential in order to guide the design of new immunotherapy strategies for clinical use.

TGF-β-Mediated Epithelial-Mesenchymal Transition and Cancer Metastasis

Transforming growth factor β (TGF-β) is a secreted cytokine that regulates cell proliferation, migration, and the differentiation of a plethora of different cell types. Consistent with these findings, TGF-β plays a key role in controlling embryogenic development, inflammation, and tissue repair, as well as in maintaining adult tissue homeostasis. TGF-β elicits a broad range of context-dependent cellular responses, and consequently, alterations in TGF-β signaling have been implicated in many diseases, including cancer. During the early stages of tumorigenesis, TGF-β acts as a tumor suppressor by inducing cytostasis and the apoptosis of normal and premalignant cells. However, at later stages, when cancer cells have acquired oncogenic mutations and/or have lost tumor suppressor gene function, cells are resistant to TGF-β-induced growth arrest, and TGF-β functions as a tumor promotor by stimulating tumor cells to undergo the so-called epithelial-mesenchymal transition (EMT). The latter leads to metastasis and chemotherapy resistance. TGF-β further supports cancer growth and progression by activating tumor angiogenesis and cancer-associated fibroblasts and enabling the tumor to evade inhibitory immune responses. In this review, we will consider the role of TGF-β signaling in cell cycle arrest, apoptosis, EMT and cancer cell metastasis. In particular, we will highlight recent insights into the multistep and dynamically controlled process of TGF-β-induced EMT and the functions of miRNAs and long noncoding RNAs in this process. Finally, we will discuss how these new mechanistic insights might be exploited to develop novel therapeutic interventions.

Lymphatic Migration of Immune Cells

Lymphatic vessels collect interstitial fluid that has extravasated from blood vessels and return it to the circulatory system. Another important function of the lymphatic network is to facilitate immune cell migration and antigen transport from the periphery to draining lymph nodes. This migration plays a crucial role in immune surveillance, initiation of immune responses and tolerance. Here we discuss the significance and mechanisms of lymphatic migration of innate and adaptive immune cells in homeostasis, inflammation and cancer.

TGF-β signaling in cancer

Signals from the transforming growth factor-β (TGF-β) superfamily mediate a broad spectrum of cellular processes and are deregulated in many diseases, including cancer. TGF-β signaling has dual roles in tumorigenesis. In the early phase of tumorigenesis, TGF-β has tumor suppressive functions, primarily through cell cycle arrest and apoptosis. However, in the late stage of cancer, TGF-β acts as a driver of tumor progression and metastasis by increasing tumor cell invasiveness and migration and promoting chemo-resistance. Here, we briefly review the mechanisms and functions of TGF-β signaling during tumor progression and discuss the therapeutic potentials of targeting the TGF-β pathway in cancer.

Dendritic Cells in the Cross Hair for the Generation of Tailored Vaccines

Vaccines represent the discovery of utmost importance for global health, due to both prophylactic action to prevent infections and therapeutic intervention in neoplastic diseases. Despite this, current vaccination strategies need to be refined to successfully generate robust protective antigen-specific memory immune responses. To address this issue, one possibility is to exploit the high efficiency of dendritic cells (DCs) as antigen-presenting cells for T cell priming. DCs functional plasticity allows shaping the outcome of immune responses to achieve the required type of immunity. Therefore, the choice of adjuvants to guide and sustain DCs maturation, the design of multifaceted vehicles, and the choice of surface molecules to specifically target DCs represent the key issues currently explored in both preclinical and clinical settings. Here, we review advances in DCs-based vaccination approaches, which exploit direct in vivo DCs targeting and activation options. We also discuss the recent findings for efficient antitumor DCs-based vaccinations and combination strategies to reduce the immune tolerance promoted by the tumor microenvironment.

Human dendritic cell sequestration onto the Necator americanus larval sheath during ex-sheathing: a possible mechanism for immune privilege

Despite the profound health implications of Necator americanus infection in humans, many aspects of its interaction with the host immune system are poorly understood. Here we investigated the early events at the interface of N. americanus larvae (L3) and human dendritic cells (DCs). Our data show that co-culturing DCs and the larvae trigger ex-sheathing of hookworms rapidly where a majority of DCs are sequestered onto the larval sheath allowing the ex-sheathed larvae to migrate away unchallenged. Intriguingly, DCs show negligible interaction with the ex-sheathed larvae, alluding to differences between the surface chemistry of the larva and its sheath. Furthermore, blocking of two key C-type lectin receptors on DC surface (i.e. DC-SIGN and mannose receptor) resulted in inhibition of ex-sheathing process and DC sequestration, highlighting the importance of C-type lectins on DCs in the induction of the ex-sheathing. Analyses of DC phenotype and cytokine profile after co-culture with the N. americanus larvae showed an immature phenotype as evidenced by the low expression of the maturation markers and cytokines. These data provide new insights into early events at the interface of human DCs and N. americanus larvae and could explain how L3 evade immune recognition upon initial interaction with DCs.

The Role of Transforming Growth Factor Beta-1 in the Progression of HIV/AIDS and Development of Non-AIDS-Defining Fibrotic Disorders

Even after attainment of sustained viral suppression following implementation of highly active antiretroviral therapy, HIV-infected persons continue to experience persistent, low-grade, systemic inflammation. Among other mechanisms, this appears to result from ongoing microbial translocation from a damaged gastrointestinal tract. This HIV-related chronic inflammatory response is paralleled by counteracting, but only partially effective, biological anti-inflammatory processes. Paradoxically, however, this anti-inflammatory response not only exacerbates immunosuppression but also predisposes for development of non-AIDS-related, non-communicable disorders. With respect to the pathogenesis of both sustained immunosuppression and the increased frequency of non-AIDS-related disorders, the anti-inflammatory/profibrotic cytokine, transforming growth factor-β1 (TGF-β1), which remains persistently elevated in both untreated and virally suppressed HIV-infected persons, may provide a common link. In this context, the current review is focused on two different, albeit related, harmful activities of TGF-β1 in HIV infection. First, on the spectrum of anti-inflammatory/immunosuppressive activities of TGF-β1 and the involvement of this cytokine, derived predominantly from T regulatory cells, in driving disease progression in HIV-infected persons via both non-fibrotic and profibrotic mechanisms. Second, the possible involvement of sustained elevations in circulating and tissue TGF-β1 in the pathogenesis of non-AIDS-defining cardiovascular, hepatic, pulmonary and renal disorders, together with a brief comment on potential TGF-β1-targeted therapeutic strategies.

Disrupted fibroblastic reticular cells and interleukin-7 expression in tumor draining lymph nodes

The immune system of patients with cancer is usually in an inhibitory state. Lymph node (LN) draining of pathological sites provides a suitable microenvironment where adaptive immune responses mainly occur. However, the microenvironment in the tumor draining lymph nodes (TDLNs) of patients with cancer appears to be in favor of tolerance. The effects of tumor cells on TDLNs have not been elaborated clearly. The present results have indicated that tumor cells may directly affect TDLNs by decreasing the fibroblastic reticular cell population that led to less interleukin-7 secretion. As a result, the number of T cells in TDLNs declined with reduced survival signals. A decreased number of T cells in TDLNs means weakened ability of immune surveillance. Clinically, these results were also confirmed in LN biopsies from patients with colon cancer at different clinical stages. Results of the present study showed that tumor cells may directly inhibit the immunological function of TDLNs.

Regulation of Innate and Adaptive Immunity by TGFβ

Immune regulation by cytokines is crucial in maintaining immune homeostasis, promoting responses to infection, resolving inflammation, and promoting immunological memory. Additionally, cytokine responses drive pathology in immune-mediated disease. A crucial cytokine in the regulation of all aspects of an immune response is transforming growth factor beta (TGFβ). Although best known as a crucial regulator of T cell responses, TGFβ plays a vital role in regulating responses mediated by virtually every innate and adaptive immune cell, including dendritic cells, B cells, NK cells, innate lymphoid cells, and granulocytes. Here, we review our current knowledge of how TGFβ regulates the immune system, highlighting the multifunctional nature of TGFβ and how its function can change depending on location and context of action.

TGFΒ-induced transcription in cancer

The Transforming Growth Factor-beta (TGFβ) pathway mediates a broad spectrum of cellular processes and is involved in several diseases, including cancer. TGFβ has a dual role in tumours, acting as a tumour suppressor in the early phase of tumorigenesis and as a tumour promoter in more advanced stages. In this review, we discuss the effects of TGFβ-driven transcription on all stages of tumour progression, with special focus on lung cancer. Since some TGFβ target genes are specifically involved in promoting metastasis, we speculate that these genes might be good targets to block tumour progression without compromising the tumour suppressor effects of the TGFβ pathway.

Migration of dendritic cells to the lymph nodes and its enhancement to drive anti-tumor responses

Better prognoses associated with increased T cell infiltration of tumors, as seen with chimeric antigen receptor (CAR) T cell therapies and immune checkpoint inhibitors, portray the importance and potential of the immune system in controlling tumors. This has rejuvenated the field of cancer immunotherapy leading to an increasing number of immunotherapies developed for cancer patients. Dendritic Cells (DCs) vaccines represent an appealing option for cancer immunotherapy since DCs have the ability to circumvent tolerance to tumors by its adjuvant properties and to induce memory T cells that can become persistent after initial tumor clearance to engage potential metastatic tumors. In the past, DC-based cancer vaccines have elicited only poor clinical response in cancer patients, which can be attributed to complex and a multitude of issues associated with generation, implementing, delivery of DC vaccine and their potential interaction with effector cells. The current review mainly focuses on migration/trafficking of DCs, as one of the key issues that affect the success of DC-based cancer vaccines, and discusses strategies to enhance it for cancer immunotherapy. Additionally, impact of maturation, route of DC delivery and negative effects of tumor microenvironment (TME) on DC homing to LN are reviewed. Moreover, strategies to increase the expression of genes involved in Lymph node homing, preconditioning of the vaccination site, enhancing lymph node ability to attract and receive DCs, while limiting negative impact of TME on DC migration are discussed.

Pancreatic cancer cell-derived IGFBP-3 contributes to muscle wasting

Background

Progressive loss of skeletal muscle, termed muscle wasting, is a hallmark of cancer cachexia and contributes to weakness, reduced quality of life, as well as poor response to therapy. Previous studies have indicated that systemic host inflammatory response regarding tumor development results in muscle wasting. However, how tumor directly regulates muscle wasting via tumor-derived secreted proteins is still largely unknown.

Methods

In this study, we performed bioinformatics analysis in two datasets of pancreatic ductal adenocarcinoma, which causes cancer cachexia and muscle wasting with the highest prevalence, and uncovered that IGFBP3, which encodes IGF-binding protein-3 (IGFBP-3), is dramatically up-regulated in pancreatic tumor samples. We also verified the wasting effect of IGFBP-3 on C2C12 muscle cells with biochemical and genetic assays.

Results

IGFBP-3 potently leads to impaired myogenesis and enhanced muscle protein degradation, the major features of muscle wasting, via IGF signaling inhibition. Moreover, conditioned medium from Capan-1 pancreatic cancer cells, which contains abundant IGFBP-3, significantly induces muscle cell wasting. This wasting effect is potently alleviated by IGFBP3 knockdown in Capan-1 cells or IGFBP-3 antibody neutralization. Strikingly, compared to muscle cells, IGF signaling and proliferation rate of Capan-1 cells were rarely affected by IGFBP-3 treatment.

Conclusions

Our results demonstrated that pancreatic cancer cells induce muscle wasting via IGFBP-3 production.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-016-0317-z) contains supplementary material, which is available to authorized users.

Chronic Gastrointestinal Nematode Infection Mutes Immune Responses to Mycobacterial Infection Distal to the Gut

Helminth infections have been suggested to impair the development and outcome of Th1 responses to vaccines and intracellular microorganisms. However, there are limited data regarding the ability of intestinal nematodes to modulate Th1 responses at sites distal to the gut. In this study, we have investigated the effect of the intestinal nematode Heligmosomoides polygyrus bakeri on Th1 responses to Mycobacterium bovis bacillus Calmette-Guérin (BCG). We found that H. polygyrus infection localized to the gut can mute BCG-specific CD4(+) T cell priming in both the spleen and skin-draining lymph nodes. Furthermore, H. polygyrus infection reduced the magnitude of delayed-type hypersensitivity (DTH) to PPD in the skin. Consequently, H. polygyrus-infected mice challenged with BCG had a higher mycobacterial load in the liver compared with worm-free mice. The excretory-secretory product from H. polygyrus (HES) was found to dampen IFN-γ production by mycobacteria-specific CD4(+) T cells. This inhibition was dependent on the TGF-βR signaling activity of HES, suggesting that TGF-β signaling plays a role in the impaired Th1 responses observed coinfection with worms. Similar to results with mycobacteria, H. polygyrus-infected mice displayed an increase in skin parasite load upon secondary infection with Leishmania major as well as a reduction in DTH responses to Leishmania Ag. We show that a nematode confined to the gut can mute T cell responses to mycobacteria and impair control of secondary infections distal to the gut. The ability of intestinal helminths to reduce DTH responses may have clinical implications for the use of skin test-based diagnosis of microbial infections.

Dendritic cell defects in the colorectal cancer

Colorectal cancer (CRC) results from the accumulation of both genetic and epigenetic alterations of the genome. However, also the formation of an inflammatory milieu plays a pivotal role in tumor development and progression. Dendritic cells (DCs) play a relevant role in tumor by exerting differential pro-tumorigenic and anti-tumorigenic functions, depending on the local milieu. Quantitative and functional impairments of DCs have been widely observed in several types of cancer, including CRC, representing a tumor-escape mechanism employed by cancer cells to elude host immunosurveillance.

Understanding the interactions between DCs and tumors is important for comprehending the mechanisms of tumor immune surveillance and escape, and provides novel approaches to therapy of cancer. This review summarizes updated information on the role of the DCs in colon cancer development and/or progression.

Human mesothelioma induces defects in dendritic cell numbers and antigen-processing function which predict survival outcomes

Mesothelioma is an almost invariably fatal tumor with chemotherapy extending survival by a few months. One immunotherapeutic strategy is to target dendritic cells (DCs), key antigen-presenting cells involved in antigen presentation, to induce antigen-specific T cell responses. However, DC-targeting will only be effective if DCs are fit-for-purpose, and the functional status of DCs in mesothelioma patients was not clear. We found that mesothelioma patients have significantly decreased numbers of circulating myeloid (m)DC1 cells, mDC2 cells and plasmacytoid (p)DCs relative to healthy age and gender-matched controls. Blood monocytes from patients could not differentiate into immature monocyte-derived DCs (MoDCs), indicated by a significantly reduced ability to process antigen and reduced expression of costimulatory (CD40, CD80 and CD86) and MHC (HLA-DR) molecules, relative to controls. Activation of mesothelioma-derived MoDCs with LPS+/-IFNγ generated partially mature MoDCs, evident by limited upregulation of the maturation marker, CD83, and the costimulatory markers. Attempts to rescue mesothelioma-derived DC function using CD40Ligand(L) also failed, indicated by maintenance of antigen-processing capacity and limited upregulation of CD40, CD83, CD86 and HLA-DR. These data suggest that mesothelioma patients have significant numerical and functional DC defects and that their reduced capacity to process antigen and reduced expression of costimulatory molecules could induce anergized/tolerized T cells. Nonetheless, survival analyses revealed that individuals with mesothelioma and higher than median levels of mDC1s and/or whose MoDCs matured in response to LPS, IFNγ or CD40L lived longer, implying their selection for DC-targeting therapy could be promising especially if combined with another treatment modality.

The TGF-β superfamily in dendritic cell biology

The TGF-β superfamily consists of a large group of pleiotropic cytokines that are involved in the regulation of many developmental, physiological and pathological processes. Dendritic cells are antigen-presenting cells that play a key role in innate and adaptive immune responses. Dendritic cells have a complex relationship with the TGF-β cytokine superfamily being both source and targets for many of these cytokines. Some TGF-β family members are expressed by dendritic cells and modulate immune responses, for instance through the induction of T cell polarization. Others play a crucial role in the development and function of the different dendritic cell subsets. This review summarizes the current knowledge on the role of TGF-β family cytokines in dendritic cell biology, focusing on TGF-β as well as on other, less characterized, members of these important immune mediators.

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.

Immunosuppressive effect of renal cell carcinoma on phenotype and function of dendritic cells

Dendritic cells (DCs) play an important role in anti-renal cell carcinoma (RCC) immunity. The aim of the study was to investigate effect of mimic RCC microenvironment on phenotype and function of DCs. We isolated conditioned media (CM) from supernatants of culturing RCC cells and adjacent non-RCC cells in patients. CD14+ monocytes were obtained from healthy donors. The monocytes derived DCs were treated by RCC CM and non-RCC CM. Maturation markers CD80, CD83, CD86, and HLA-DR on DCs were analyzed using flow cytometry, while the levels of IL-10, TGF-β, and IL12p70 in supernatants were examined by ELISA. The DCs migration treated with RCC CM and non-RCC CM was investigated using transwell assay. The DCs treated and allogenic T cells were co-cultured for detecting T-cell proliferation and change of phenotype on the T cells. Our results indicated that RCC CM inhibited the up-regulation of CD80,CD83, CD86, and HLA-DR in response to LPS in treated DCs and increased IL-10 and TGF-β secretion but reduced IL12p70 production. Moreover, the migration ability of DCs treated with RCC CM was also inhibited, compared to DCs treated with adjacent non-RCC CM. In addition, T-cell proliferation was suppressed in co-culture assay with DCs treated with RCC CM; proportion CD25+Foxp3+ regulatory T cells were induced to increase. This study suggests that RCC CM can inhibit maturation of DCs and impair its function; moreover, DCs treated with RCC CM induce regulatory T cells increase, thus could contribute RCC escape from antitumor immunity.

TGF-β1 precursor and CD8 are potential prognostic and predictive markers in operated breast cancer

The transforming growth factor β1 (TGF-β1) and CD8-positive T cells are two important immune factors that function at opposite directions. The purpose of this study was to verify the relationship between the two factors and their associations with long-term effects of adjuvant chemotherapy or endocrine therapy in breast cancer. Expression of TGF-β1 precursor and CD8 was immunohistochemically detected on surgically-obtained tumor samples of 130 (stage I-III) invasive breast carcinomas from Chinese subjects, who were followed up for a mean time of 112 months. Interstitial CD8-positive cells and TGF-β1 precursor-positive cells adjacent to tumor nests were counted. Infiltration of CD8-positive lymphocytes into tumor nests and TGF-β1 precursor expression in tumor cells were observed and survival analysis was performed. Our results showed that density of interstitial CD8-positive lymphocytes was an independent adverse prognostic factor for distant disease-free survival (DDFS) (HR=8.416, 95% CI=1.636-43.292, P=0.011) in hormone receptor-positive patients who were on adjuvant endocrine therapy. For breast cancer patients who did not receive adjuvant chemotherapy, those without infiltration of CD8-positive cells into tumor nests had a shorter overall survival (OS) than their counterparts with CD8-positive cell infiltration into tumor nests (Log-Rank, P=0.003). But OS of patients without infiltration of CD8-positive cells into tumor nests was significantly prolonged by adjuvant chemotherapy (Log-Rank, P=0.013) and paralleled that of patients with CD8-positive cell infiltration. Although OS was shorter in the tumor cell TGF-β1 precursor (t-TGF-β1-pre)-positive patients than in the negative patients in patients without receiving chemotherapy (P=0.053), OS of t-TGF-β1-pre-positive patients was significantly prolonged by adjuvant chemotherapy (P=0.035) and was longer than that of t-TGF-β1-pre-negative patients. Analysis showed that t-TGF-β1-pre was an independent positive prognostic factor for DDFS (HR=0.392 95% CI=0.157-0.978, P=0.045) in patients who received adjuvant chemotherapy. This study suggested that density of interstitial CD8-positive lymphocytes was of prognostic value in hormone receptor-positive patients who received adjuvant endocrine therapy. Our study verified that adverse immunologic signatures consisting of absence of CD8-positive cells in tumor nests or expression of TGF-β1 precursor in tumor cells in breast cancer were associated with worse prognosis and significantly improved long-term survival with adjuvant chemotherapy, respectively.

Transforming growth factor beta 1 induces CXCL16 and leukemia inhibitory factor expression in osteoclasts to modulate migration of osteoblast progenitors

The processes of bone resorption and bone formation are tightly coupled in young adults, which is crucial to maintenance of bone integrity. We have documented that osteoclasts secrete chemotactic agents to recruit osteoblast lineage cells, contributing to coupling. Bone formation subsequent to bone resorption becomes uncoupled with aging, resulting in significant bone loss. During bone resorption, osteoclasts release and activate transforming growth factor beta 1 (TGF-β1) from the bone matrix; thus, elevated bone resorption increases the level of active TGF-β in the local environment during aging. In this study, we examined the influences of TGF-β1 on the ability of osteoclasts to recruit osteoblasts. TGF-β1 increased osteoclast expression of the chemokine CXCL16 to promote osteoblast migration. TGF-β1 also directly stimulated osteoblast migration; however, this direct response was blocked by conditioned medium from TGF-β1-treated osteoclasts due to the presence of leukemia inhibitory factor (LIF) in the medium. CXCL16 and LIF expression was dependent on TGF-β1 activation of Smad2 and Smad3. These results establish that TGF-β1 induces CXCL16 and LIF production in osteoclasts, which modulate recruitment of osteoblasts to restore the bone lost during the resorptive phase of bone turnover.

Bronchioloalveolar invasion in non-small cell lung cancer is associated with expression of transforming growth factor-β1

Background

Adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) with fibrous stromal invasion are newly introduced subtypes of small lung adenocarcinoma. AIS is a small localized adenocarcinoma in which growth is restricted to neoplastic cells along preexisting alveolar structures without fibrous stromal invasion. In MIA, by contrast, tumor cells have infiltrated the myofibroblastic stroma. Transforming growth factor (TGF)-β is known to be produced by progressor tumors, and excessive TGF-β contributes to a pathological excess of tissue fibrosis. TGF-β1 is the most abundant isoform, and its expression is a key event fostering tumor invasion and metastasis. We therefore analyzed the relationship between TGF-β1 expression and clinicopathological microinvasion in patients with small lung adenocarcinoma.

Methods

The study participants were 45 patients who underwent curative surgery for AIS and MIA 3 cm or less in size. Those tumors were assessed based on immunohistochemical staining using anti-TGF-β1 antibody. The TGF-β1 status was assessed immunohistochemically using the Allred 8-unit system.

Results

The rates of TGF-β1 positivity in the AIS and MIA groups were 27.3% and 65.2%, respectively (P <0.05). The median of Allred score was 0.5 (range 0–5) in the AIS group and 3.0 (range 0–6) in the MIA group (P = 0.0017).

Conclusions

We suggest that TGF-β1 expression is likely to be significantly stronger in patients with MIA than in those with AIS, and the increased expression may be associated with minimal invasion and infiltration of the myofibroblastic stroma.