Antitumoral efficacy of DNA nanoparticles in murine models of lung cancer and pulmonary metastasis

Nanomaterial-Interleukin Combination for Boosting NK Cell-Based Tumor Immunotherapy

The use of natural killer (NK) cell-based immunotherapy has been extensively explored in clinical trials for multiple types of tumors and has surfaced as a promising approach in tumor immunotherapy. Interleukins (ILs), a vital class of cytokines, play a crucial role in regulating several functions of NK cells, thereby becoming a focal point in the advancement of NK cell-based therapies. Nonetheless, the use of ILs as single agents is significantly constrained by their short half-life, limited efficacy, and adverse reactions. Currently, nanomaterials are being progressively employed in the delivery of ILs to enhance NK cell-based immunotherapy. However, there is currently a lack of comprehensive reviews summarizing the design of NK-cell-targeted nanomaterials and related systems for delivery of ILs. Furthermore, certain nanomaterials, either alone or in conjunction with other therapeutics, can also promote the secretion of ILs, representing a promising avenue for further exploration. Accordingly, this review begins by outlining various types of ILs and subsequently discusses the advancements in applying nanomaterials for IL delivery. It also examines the potential of nanomaterials to enhance IL secretion from other immune cells, thereby influencing the NK cell functionality. Lastly, this review addresses the challenges associated with using nanomaterials in these contexts and offers perspectives for future research. This study aims to provide valuable insights into the development of NK cell immunotherapy and innovative nanomaterial-based drug delivery systems.

Nanoformulations: Reforming treatment for non-small cell lung cancer metastasis

Non-small cell lung cancer (NSCLC) is frequently diagnosed at an advanced stage, with 20 % of cases presenting as localized disease, 25 % with regional metastasis, and 55 % with distant metastasis, contributing significantly to increased morbidity and mortality rates. Current treatments, including chemotherapy, immunotherapy, radiotherapy and targeted therapy, have shown therapeutic efficacy but are limited by issues such as lack of specificity, cytotoxicity, and therapeutic resistance. Nanoparticles (NPs) offer promising solutions to these challenges by enhancing drug penetration and retention, improving biocompatibility and stability, and achieving greater precision in targeting cancer cells. This review provides insights into various types of NPs utilized in anti-metastatic drug delivery, emphasizing their ability to enhance the efficacy of existing chemotherapeutics for the prophylaxis of metastatic NSCLC. The usage of NPs as carriers of synthetic and natural compounds aimed at inhibiting cancer cell migration and invasion have also been reviewed. Special attention has been given to biomimetic nanomaterials including extracellular vesicles, exosomes and engineered NPs, that are capable of targeting molecular pathways such as EMT, p53 and PI3K/Akt to treat metastatic NSCLC. Additionally, emphasis has been given to clinical trials of these nanoformulations and their efficacy. Although therapeutic outcomes have demonstrated certain improvements, challenges related to toxicity persist, highlighting the need for further optimization of these formulations to enhance safety and efficacy. Finally, we discuss the current limitations and future perspectives for integrating NPs into clinical settings as novel therapeutic agents for lung cancer metastasis.

A novel oncolytic Vaccinia virus armed with IL-12 augments antitumor immune responses leading to durable regression in murine models of lung cancer

Oncolytic vaccinia viruses (VVs) are potent stimulators of the immune system and induce immune-mediated tumor clearance and long-term surveillance against tumor recurrence. As such they are ideal treatment modalities for solid tumors including lung cancer. Here, we investigated the use of VVL-m12, a next-generation, genetically modified, interleukin-12 (IL-12)-armed VV, as a new therapeutic strategy to treat murine models of lung cancer and as a mechanism of increasing lung cancer sensitivity to antibody against programmed cell death protein 1 (α-PD1) therapy. The cytotoxicity and replication of VVL-m12, VVL-h12 and control VVs were assessed in lung cancer cell lines. Subcutaneous lung cancer mouse models were established to investigate the anti-tumor activity of the viruses after intratumoral delivery in an immunocompetent disease model. Synergy with α-PD1 or a VV armed with soluble PD-1 (VV-sPD1) was investigated and functional mechanisms behind efficacy probed. Tumor-targeted VVL-m12 replicated to high levels, was cytotoxic in lung cancer cell lines. VVL-m12 demonstrated superior antitumor efficacy in subcutaneous lung cancer models compared with other VVs examined. Importantly, rational combination of VVL-m12 and PD-1 blockade worked synergistically to significantly enhance survival of animals and safely cured lung cancer with no evidence of recurrence. VVL-m12 therapy induced increased intratumoral infiltration of CD4+ and CD8+ T cells and was able to clear tumor at early time points via increased induction and infiltration of effector T cells and central memory T cells (TCM). In addition, VVL-m12 increased dendritic cell activation, induced polarization of M2 macrophages towards an M1 phenotype, and inhibited tumor angiogenesis in vivo. These results demonstrate that VVL-12 has strong potential as a safe and effective antitumor therapeutic for lung cancer. Importantly, VVL-12 can sensitize lung cancers to α-PD1 antibody therapy, and the combined regime creates a highly effective treatment option for patients.

Interleukin-12 Delivery Strategies and Advances in Tumor Immunotherapy

Interleukin-12 (IL-12) is considered to be a promising cytokine for enhancing an antitumor immune response; however, recombinant IL-12 has shown significant toxicity and limited efficacy in early clinical trials. Recently, many strategies for delivering IL-12 to tumor tissues have been developed, such as modifying IL-12, utilizing viral vectors, non-viral vectors, and cellular vectors. Previous studies have found that the fusion of IL-12 with extracellular matrix proteins, collagen, and immune factors is a way to enhance its therapeutic potential. In addition, studies have demonstrated that viral vectors are a good platform, and a variety of viruses such as oncolytic viruses, adenoviruses, and poxviruses have been used to deliver IL-12-with testing previously conducted in various cancer models. The local expression of IL-12 in tumors based on viral delivery avoids systemic toxicity while inducing effective antitumor immunity and acting synergistically with other therapies without compromising safety. In addition, lipid nanoparticles are currently considered to be the most mature drug delivery system. Moreover, cells are also considered to be drug carriers because they can effectively deliver therapeutic substances to tumors. In this article, we will systematically discuss the anti-tumor effects of IL-12 on its own or in combination with other therapies based on different delivery strategies.

Nanotechnology-empowered lung cancer therapy: From EMT role in cancer metastasis to application of nanoengineered structures for modulating growth and metastasis

Lung cancer is one of the leading causes of death in both males and females, and it is the first causes of cancer-related deaths. Chemotherapy, surgery and radiotherapy are conventional treatment of lung cancer and recently, immunotherapy has been also appeared as another therapeutic strategy for lung tumor. However, since previous treatments have not been successful in cancer therapy and improving prognosis and survival rate of lung tumor patients, new studies have focused on gene therapy and targeting underlying molecular pathways involved in lung cancer progression. Nanoparticles have been emerged in treatment of lung cancer that can mediate targeted delivery of drugs and genes. Nanoparticles protect drugs and genes against unexpected interactions in blood circulation and improve their circulation time. Nanoparticles can induce phototherapy in lung cancer ablation and mediating cell death. Nanoparticles can induce photothermal and photodynamic therapy in lung cancer. The nanostructures can impair metastasis of lung cancer and suppress EMT in improving drug sensitivity. Metastasis is one of the drawbacks observed in lung cancer that promotes migration of tumor cells and allows them to establish new colony in secondary site. EMT can occur in lung cancer and promotes tumor invasion. EMT is not certain to lung cancer and it can be observed in other human cancers, but since lung cancer has highest incidence rate, understanding EMT function in lung cancer is beneficial in improving prognosis of patients. EMT induction in lung cancer promotes tumor invasion and it can also lead to drug resistance and radio-resistance. Moreover, non-coding RNAs and pharmacological compounds can regulate EMT in lung cancer and EMT-TFs such as Twist and Slug are important modulators of lung cancer invasion that are discussed in current review.

Combination of thermal ablation by focused ultrasound, pFAR4-IL-12 transfection and lipidic adjuvant provide a distal immune response

Aim:

Gene-based immunotherapy against cancer is limited by low gene transfer efficiency. In the literature, interleukin-12 (IL-12) encoding plasmid associated with sonoporation has been shown to enhance antitumoral activity. Moreover, non-viral carriers and high-frequency ultrasound have both been shown to promote immune response activation. Here, IL-12 encoding plasmid, non-viral carrier stimulating the immune response and focused ultrasound were combined in order to improve the antitumoral efficiency.

Methods:

In order to enhance a gene-based antitumoral immune response, home-made lipids Toll-like receptor 2 (TLR2) agonists and plasmid free of antibiotic resistance version 4 (pFAR4), a mini-plasmid, encoding the IL-12 cytokine were combined with high-intensity focused ultrasound (HIFU). The lipid composition and the combination conditions were selected following in vitro and in vivo preliminary studies. The expression of IL-12 from our plasmid construct was measured in vitro and in vivo. The combination strategy was evaluated in mice bearing colon carcinoma cells (CT26) tumors following their weight, tumor volume, interferon-gamma (IFN-γ), and tumor necrosis factor-alpha (TNF-α) levels in the serum and produced by splenocytes exposed to CT26 tumor cells.

Results:

Lipid-mediated cell transfection and intratumoral injection into CT26 tumor mice using pFAR4-IL-12 led to the secretion of the IL-12 cytokine into cell supernatant and mice sera, respectively. Conditions of thermal deposition using HIFU were optimized. The plasmid encoding pFAR4-IL-12 or TLR2 agonist alone had no impact on tumor growth compared with control mice, whereas the complete treatment consisting of pFAR4-IL-12, TLR2 lipid agonist, and HIFU limited tumor growth. Moreover, only the complete treatment increased significantly mice survival and provided an abscopal effect on a metastatic CT26 model.

Conclusions:

The HIFU condition was highly efficient to stop tumor growth. The combined therapy was the most efficient in terms of IL-12 and IFN-γ production and mice survival. The study showed the feasibility and the limits of this combined therapy which has the potential to be improved.

Integrating disulfides into a polyethylenimine gene carrier selectively boosts significant transfection activity in lung tissue enabling robust IL-12 gene therapy against metastatic lung cancers

Bioreducible polyethylenimines (SSPEIs) are promising non-viral carriers for cancer gene therapy. However, the availability of significant gene transfection activity by SSPEIs remains a challenge. Herein, an essential step was taken to ascertain whether or not the disulfide bonds of SSPEIs play a critical role in promoting significant gene transfection activity in different tissues. Initially, a disulfide-linked linear polyethylenimine (denoted as SSLPEI) consisting of one 5.0 kDa LPEI main chain and three disulfide-linked 5.7 kDa LPEI grafts was designed and prepared to possess similar molecular weight with commercialized 25 kDa LPEI as a positive control. The SSLPEI could induce superior in vitro transfection activity in different cells to the LPEI control as well as low cytotoxicity. Notably, such enhanced in vitro transfection effect by the SSLPEI was more marked in type-II alveolar epithelial cells compared to different cancer cells. In a Balb/c nude mouse model bearing SKOV-3 tumor, the SSLPEI caused parallel level of transgene expression with the LPEI control in the tumor but significantly higher level in the mouse lung. Furthermore, the SSLPEI and LPEI groups afforded an identical antitumor efficacy against the SKOV-3 tumor via intravenous delivery of a shRNA for silencing VEGF expression in the tumor. However, via intravenous delivery of an interleukin-12 (IL-12) gene into metastatic lung cancers in a C57BL/6 mouse model, the SSLPEI group exerted markedly higher IL-12 expression level in the mouse lung and peripheral blood as compared to the LPEI group, thereby boosting IL-12 immunotherapy against the lung metastasis with longer medium survival time. The results of this work elicit that the disulfide bonds of SSPEIs play a pivotal role in enhancing gene transfection activity selectively in the lung tissue rather than solid tumor, enabling high translational potential of SSPEIs for non-viral gene therapy against metastatic lung cancers.

Nanoparticle-mediated tumor cell expression of mIL-12 via systemic gene delivery treats syngeneic models of murine lung cancers

Treatment of cancers in the lung remains a critical challenge in the clinic for which gene therapy could offer valuable options. We describe an effective approach through systemic injection of engineered polymer/DNA nanoparticles that mediate tumor-specific expression of a therapeutic gene, under the control of the cancer-selective progression elevated gene 3 (PEG-3) promoter, to treat tumors in the lungs of diseased mice. A clinically tested, untargeted, polyethylenimine carrier was selected to aid rapid transition to clinical studies, and a CpG-free plasmid backbone and coding sequences were used to reduce inflammation. Intravenous administration of nanoparticles expressing murine single-chain interleukin 12, under the control of PEG-3 promoter, significantly improved the survival of mice in both an orthotopic and a metastatic model of lung cancer with no marked symptoms of systemic toxicity. These outcomes achieved using clinically relevant nanoparticle components raises the promise of translation to human therapy.

Nucleic Acid-Based Approaches for Tumor Therapy

Within the last decade, the introduction of checkpoint inhibitors proposed to boost the patients' anti-tumor immune response has proven the efficacy of immunotherapeutic approaches for tumor therapy. Furthermore, especially in the context of the development of biocompatible, cell type targeting nano-carriers, nucleic acid-based drugs aimed to initiate and to enhance anti-tumor responses have come of age. This review intends to provide a comprehensive overview of the current state of the therapeutic use of nucleic acids for cancer treatment on various levels, comprising (i) mRNA and DNA-based vaccines to be expressed by antigen presenting cells evoking sustained anti-tumor T cell responses, (ii) molecular adjuvants, (iii) strategies to inhibit/reprogram tumor-induced regulatory immune cells e.g., by RNA interference (RNAi), (iv) genetically tailored T cells and natural killer cells to directly recognize tumor antigens, and (v) killing of tumor cells, and reprograming of constituents of the tumor microenvironment by gene transfer and RNAi. Aside from further improvements of individual nucleic acid-based drugs, the major perspective for successful cancer therapy will be combination treatments employing conventional regimens as well as immunotherapeutics like checkpoint inhibitors and nucleic acid-based drugs, each acting on several levels to adequately counter-act tumor immune evasion.

Cytokines in clinical cancer immunotherapy

Cytokines are soluble proteins that mediate cell-to-cell communication. Based on the discovery of the potent anti-tumour activities of several pro-inflammatory cytokines in animal models, clinical research led to the approval of recombinant interferon-alpha and interleukin-2 for the treatment of several malignancies, even if efficacy was only modest. These early milestones in immunotherapy have been followed by the recent addition to clinical practice of antibodies that inhibit immune checkpoints, as well as chimeric antigen receptor T cells. A renewed interest in the anti-tumour properties of cytokines has led to an exponential increase in the number of clinical trials that explore the safety and efficacy of cytokine-based drugs, not only as single agents, but also in combination with other immunomodulatory drugs. These second-generation drugs under clinical development include known molecules with novel mechanisms of action, new targets, and fusion proteins that increase half-life and target cytokine activity to the tumour microenvironment or to the desired effector immune cells. In addition, the detrimental activity of immunosuppressive cytokines can be blocked by antagonistic antibodies, small molecules, cytokine traps or siRNAs. In this review, we provide an overview of the novel trends in the cytokine immunotherapy field that are yielding therapeutic agents for clinical trials.

New trends in antitumor vaccines in melanoma

Antitumor therapeutic vaccines aim at priming an effector immune response able to recognize and kill tumor cells. Antitumor vaccines are composed of at least two main components: the tumor antigens and the adjuvant. Metastatic advanced melanoma has been a model disease to test novel advances in vaccine design due to the intrinsic immunogenicity of this tumor and the accessibility to melanoma lesions to monitor the immune response. In spite of a large number of clinical trials, clinical benefit remains elusive. The clinical success of monoclonal antibodies targeting immune check-points has renewed interest in novel vaccine strategies such as personalized neoantigen-based vaccines.

Genetic Modification of the Lung Directed Toward Treatment of Human Disease

Genetic modification therapy is a promising therapeutic strategy for many diseases of the lung intractable to other treatments. Lung gene therapy has been the subject of numerous preclinical animal experiments and human clinical trials, for targets including genetic diseases such as cystic fibrosis and α1-antitrypsin deficiency, complex disorders such as asthma, allergy, and lung cancer, infections such as respiratory syncytial virus (RSV) and Pseudomonas, as well as pulmonary arterial hypertension, transplant rejection, and lung injury. A variety of viral and non-viral vectors have been employed to overcome the many physical barriers to gene transfer imposed by lung anatomy and natural defenses. Beyond the treatment of lung diseases, the lung has the potential to be used as a metabolic factory for generating proteins for delivery to the circulation for treatment of systemic diseases. Although much has been learned through a myriad of experiments about the development of genetic modification of the lung, more work is still needed to improve the delivery vehicles and to overcome challenges such as entry barriers, persistent expression, specific cell targeting, and circumventing host anti-vector responses.

Doxorubicin Hydrochloride Loaded Zymosan-Polyethylenimine Biopolymeric Nanoparticles for Dual 'Chemoimmunotherapeutic' Intervention in Breast Cancer

OBJECTIVE

To utilize nanoparticles produced by condensation of zymosan (an immunotherapeutic polysaccharide) with pegylated polyethylenimine (PEG-PEI) for dual intervention in breast cancer by modulating tumor microenvironment and direct chemotherapy.

METHOD

Positively charged PEG-PEI and negatively charged sulphated zymosan were utilized for electrostatic complexation of chemoimmunotherapeutic nanoparticles (ChiNPs). ChiNPs were loaded with doxorubicin hydrochloride (DOX) for improved delivery at tumor site and were tested for in-vivo tolerability. Biodistribution studies were conducted to showcase their effective accumulation in tumor hypoxic regions where tumor associated macrophages (TAMs) are preferentially recruited.

RESULTS

ChiNPs modulated TAMs differentiation resulting in decrement of CD206 positive population. This immunotherapeutic action was furnished by enhanced expression of Th1 specific cytokines. ChiNPs also facilitated an anti-angiogenetic effect which further reduces the possibility of tumor progression and metastasis.

Gene therapy approaches against cancer using in vivo and ex vivo gene transfer of interleukin-12

IL-12 is an immunostimulatory cytokine with strong antitumor properties. Systemic administration of IL-12 in cancer patients led to severe toxic effects, prompting the development of gene therapy vectors able to express this cytokine locally in tumors. Both nonviral and viral vectors have demonstrated a high antitumor efficacy in preclinical tumor models. Some of these vectors, including DNA electroporation, adenovirus and ex vivo transduced dendritic cells, were tested in patients, showing low toxicity and moderate antitumor efficacy. IL-12 activity can be potentiated by molecules with immunostimulatory, antiangiogenic or cytotoxic activity. These combination therapies are of clinical interest because they could lower the threshold for IL-12 efficacy, increasing the therapeutic potential of gene therapy and preventing the toxicity mediated by this cytokine.

STING, nanoparticles, autoimmune disease and cancer: a novel paradigm for immunotherapy?

DNA has potent immunogenic properties that are useful to enhance vaccine efficacy. DNA also incites hyperinflammation and autoimmunity if DNA sensing is not regulated. Paradoxically, DNA regulates immunity and autoimmunity when administered systemically as DNA nanoparticles. DNA nanoparticles regulated immunity via cytosolic DNA sensors that activate the signaling adaptor stimulator of interferon genes. In this review, we describe how DNA sensing to activate stimulator of interferon genes promotes regulatory responses and discuss the biological and clinical implications of these responses for understanding disease progression and designing better therapies for patients with chronic inflammatory diseases, such as autoimmune syndromes or cancer.

Cytosolic DNA sensing via the stimulator of interferon genes adaptor: Yin and Yang of immune responses to DNA

DNA is immunogenic and many cells express cytosolic DNA sensors that activate the stimulator of interferon genes (STING) adaptor to trigger interferon type I (IFN-β) release, a potent immune activator. DNA sensing to induce IFN-β triggers host immunity to pathogens but constitutive DNA sensing can induce sustained IFN-β release that incites autoimmunity. Here, we focus on cytosolic DNA sensing via the STING/IFN-β pathway that regulates immune responses. Recent studies reveal that cytosolic DNA sensing via the STING/IFN-β pathway induces indoleamine 2,3 dioxygenase (IDO), which catabolizes tryptophan to suppress effector and helper T-cell responses and activate Foxp3-lineage CD4(+) regulatory T (Treg) cells. During homeostasis, and in some inflammatory settings, specialized innate immune cells in the spleen and lymph nodes may ingest and sense cytosolic DNA to reinforce tolerance that prevents autoimmunity. However, malignancies and pathogens may exploit DNA-induced regulatory responses to suppress natural and vaccine-induced immunity to malignant and infected cells. In this review, we discuss the biologic significance of regulatory responses to DNA and novel approaches to exploit DNA-induced immune responses for therapeutic benefit. The ability of DNA to drive tolerogenic or immunogenic responses highlights the need to evaluate immune responses to DNA in physiologic settings relevant to disease progression or therapy.

Activation of the STING adaptor attenuates experimental autoimmune encephalitis

Cytosolic DNA sensing activates the stimulator of IFN genes (STING) adaptor to induce IFN type I (IFN-αβ) production. Constitutive DNA sensing to induce sustained STING activation incites tolerance breakdown, leading to autoimmunity. In this study, we show that systemic treatments with DNA nanoparticles (DNPs) induced potent immune regulatory responses via STING signaling that suppressed experimental autoimmune encephalitis (EAE) when administered to mice after immunization with myelin oligodendrocyte glycoprotein (MOG), at EAE onset, or at peak disease severity. DNP treatments attenuated infiltration of effector T cells into the CNS and suppressed innate and adaptive immune responses to myelin oligodendrocyte glycoprotein immunization in spleen. Therapeutic responses were not observed in mice treated with cargo DNA or cationic polymers alone, indicating that DNP uptake and cargo DNA sensing by cells with regulatory functions was essential for therapeutic responses to manifest. Intact STING and IFN-αβ receptor genes, but not IFN-γ receptor genes, were essential for therapeutic responses to DNPs to manifest. Treatments with cyclic diguanylate monophosphate to activate STING also delayed EAE onset and reduced disease severity. Therapeutic responses to DNPs were critically dependent on IDO enzyme activity in hematopoietic cells. Thus, DNPs and cyclic diguanylate monophosphate attenuate EAE by inducing dominant T cell regulatory responses via the STING/IFN-αβ/IDO pathway that suppress CNS-specific autoimmunity. These findings reveal dichotomous roles for the STING/IFN-αβ pathway in either stimulating or suppressing autoimmunity and identify STING-activating reagents as a novel class of immune modulatory drugs.

Targeted immunomodulation using antigen-conjugated nanoparticles

The growing prevalence of nanotechnology in the fields of biology, medicine, and the pharmaceutical industry is confounded by the relatively small amount of data on the impact of these materials on the immune system. In addition to concerns surrounding the potential toxicity of nanoparticle (NP)-based delivery systems, there is also a demand for a better understanding of the mechanisms governing interactions of NPs with the immune system. Nanoparticles can be tailored to suppress, enhance, or subvert recognition by the immune system. This 'targeted immunomodulation' can be achieved by delivery of unmodified particles, or by modifying particles to deliver drugs, proteins/peptides, or genes to a specific site. In order to elicit the desired, beneficial immune response, considerations should be made at every step of the design process: the NP platform itself, ligands, and other modifiers, the delivery route, and the immune cells that will encounter the conjugated NPs can all impact host immune responses.

Availability of polymeric nanoparticles for specific enhanced and targeted drug delivery

Over the past 20–30 years there has been quite a number of studies interested in polymeric nanoparticle (PNP) systems as a pharmaceutical approach for poorly soluble drugs, peptide drugs, gene and antibodies. Now, the products based on the PNP technologies are used in the fields of medical science, pharmaceutical science, tissue engineering and clothing, food and housing. This review focuses attention on PNPs for specific enhanced and targeted drug delivery of therapeutic drugs including peptide drugs as well as drug delivery applications of such systems. Outcomes from recent studies on polymers, how to make PNPs, pharmacokinetics and pharmacodynamics of PNPs, and the release profiles from PNPs and related systems are also described, including their pharmacokinetics and pharmacodynamics, if available. In addition, the latest PNP trends and will be described.

Delivery of therapeutic nucleic acids via transferrin and transferrin receptors: lipoplexes and other carriers

INTRODUCTION

The overexpression of transferrin (Tf) receptors on cancer cells renders them a useful target for the delivery of small-molecule drugs and nucleic acid therapeutics to these cells. This approach could alleviate the non-target effects of the drugs.

AREAS COVERED

The function of the Tf receptor, the development of Tf-lipid-DNA complexes (Tf lipoplexes), therapeutic use of lipoplexes and polymer-DNA complexes (poylplexes), and the therapeutic use of Tf-lipoplexes and anti-Tf-receptor antibody-lipoplexes are outlined. The literature search for this review was based primarily on the terms 'lipoplexes,' 'lipopolyplexes' 'transferrin,' 'transferrin receptor,' and 'gene therapy.' However, the review was not intended to be comprehensive.

EXPERT OPINION

Complexes of Tf with cationic liposomes and nucleic acids, or liposomes with covalently attached Tf or anti-transferrin receptor antibodies have been used for the delivery of therapeutic genes, antisense oligodeoxynucleotides, and short interfering RNA. Although such targeted nonviral delivery vehicles may benefit from further enhancement of their efficacy, current achievements at the cell culture and animal model level should be translated into clinical applications, restricted initially to localized delivery into accessible tissues to avoid potential systemic side-effects and non-target delivery.

Altered tryptophan metabolism as a paradigm for good and bad aspects of immune privilege in chronic inflammatory diseases

The term "immune privilege" was coined to describe weak immunogenicity (hypo-immunity) that manifests in some transplant settings. We extended this concept to encompass hypo-immunity that manifests at local sites of inflammation relevant to clinical diseases. Here, we focus on emerging evidence that enhanced tryptophan catabolism is a key metabolic process that promotes and sustains induced immune privilege, and discuss the implications for exploiting this knowledge to improve treatments for hypo-immune and hyper-immune syndromes using strategies to manipulate tryptophan metabolism.

Engineering DNA nanoparticles as immunomodulatory reagents that activate regulatory T cells

Nanoparticles containing DNA complexed with the cationic polymer polyethylenimine are efficient vehicles to transduce DNA into cells and organisms. DNA/polyethylenimine nanoparticles (DNPs) also elicit rapid and systemic release of proinflammatory cytokines that promote antitumor immunity. In this study, we report that DNPs possess previously unrecognized immunomodulatory attributes due to rapid upregulation of IDO enzyme activity in lymphoid tissues of mice. IDO induction in response to DNP treatment caused dendritic cells and regulatory T cells (Tregs) to acquire potent regulatory phenotypes. As expected, DNP treatment stimulated rapid increase in serum levels of IFN type I (IFN-αβ) and II (IFN-γ), which are both potent IDO inducers. IDO-mediated Treg activation was dependent on IFN type I receptor signaling, whereas IFN-γ receptor signaling was not essential for this response. Moreover, systemic IFN-γ release was caused by TLR9-dependent activation of NK cells, whereas TLR9 signaling was not required for IFN-αβ release. Accordingly, DNPs lacking immunostimulatory TLR9 ligands in DNA stimulated IFN-αβ production, induced IDO, and promoted regulatory outcomes, but did not stimulate potentially toxic, systemic release of IFN-γ. DNP treatment to induce IDO and activate Tregs blocked Ag-specific T cell responses elicited in vivo following immunization and suppressed joint pathology in a model of immune-mediated arthritis. Thus, DNPs lacking TLR9 ligands may be safe and effective reagents to protect healthy tissues from immune-mediated destruction in clinical hyperimmune syndromes.

Antitumoral efficacy by systemic delivery of heparin conjugated polyethylenimine-plasmid interleukin-15 complexes in murine models of lung metastasis

Gene therapy shows promising application in cancer therapy, but the lack of an ideal gene delivery system is still a tough challenge for cancer gene therapy. Previously, we prepared a novel cationic nanogel, heparin-polyethylenimine (HPEI), which had potential application in gene delivery. In the present study, we constructed a plasmid with high expression efficiency of interleukin-15 (IL15) and investigated the effects HPEI-plasmid IL15 (HPEI-pIL15) complexes on the distribution level of the lung. We then evaluated the anticancer effect of HPEI-pIL15 complexes on lung metastases of B16-F10 melanoma and CT26 colon carcinoma. These results demonstrated that intravenous injection of the HPEI-pIL15 complex exhibited the highest plasmid distribution level in the lung compared with that of PEI2K-pIL15 and PEI25K-pIL15, and mice treated with HPEI-pIL15 had a lower tumor metastasis index compared with other treatment groups. Moreover, the number of natural killer cells, which were intermingled among the tumor cells, and the level of tumor necrosis factor-α and interferon-γ in the serum also increased in the pIL15-treated mice. Furthermore, the cytotoxic activity of spleen cells also increased significantly in the HPEI-pIL15 group. In addition, induction of apoptosis and inhibition of cell proliferation in lung tumor foci in the HPEI-pIL15 group was observed. Taken together, treating lung metastasis cancer with the HPEI nanogels delivered by plasmid IL15 might be a new and interesting cancer gene therapy protocol.