Enhancement of dendritic cell-based vaccine potency by anti-apoptotic siRNAs targeting key pro-apoptotic proteins in cytotoxic CD8(+) T cell-mediated cell death

Size-selective microfluidics delineate the effects of combinatorial immunotherapy on T-cell response dynamics at the single-cell level

Cellular communication at the single-cell level holds immense potential for uncovering response heterogeneity in immune cell behaviors. However, because of significant size diversity among different immune cell types, controlling the pairing of cells with substantial size differences remains a formidable challenge. We developed a microfluidic platform for size-selective pairing (SSP) to pair single cells with up to a fivefold difference in size, achieving over 40% pairing efficiency. We used SSP to investigate the real-time effects of combinatorial immunotherapeutic stimulation on macrophage T-cell interactions at the single-cell level via fluorescence microscopy and microfluidic sampling. While combinatorial activation involving toll-like receptor (TLR) agonists and rapamycin (an mTOR inhibitor) has improved therapeutic efficacy in mice, its clinical success has been limited. Here, we investigated immune synaptic interactions and outcomes at the single-cell level in real time and compared them with bulk-level measurements. Our findings, after tracking and computationally analyzing the effects of sequential and spatiotemporal stimulations of primary mouse macrophages, suggest a regulatory role of rapamycin in dampening inflammatory outputs in T cells.

Immunotherapies landscape and associated inhibitors for the treatment of cervical cancer

Cervical cancer ranks as the fourth most common form of cancer worldwide. There is a large number of situations that may be examined in the developing world. The risk of contracting HPV (Human Papillomavirus) due to poor sanitation and sexual activity is mostly to blame for the disease's alarming rate of expansion. Immunotherapy is widely regarded as one of the most effective medicines available. The immunotherapy used to treat cervical cancer cells relies on inhibitors that block the immune checkpoint. The poly adenosine diphosphate ribose polymer inhibited cervical cancer cells by activating both the programmed death 1 (PD-1) and programmed death ligand 1 (CTLA-1) checkpoints, a strategy that has been shown to have impressive effects. Yet, immunotherapy directed towards tumors that have already been invaded by lymphocytes leaves a positive imprint on the healing process. Immunotherapy is used in conjunction with other treatments, including chemotherapy and radiation, to provide faster and more effective outcomes. In this combination therapy, several medications such as Pembrolizumab, Durvalumab, Atezolizumab, and so on are employed in clinical trials. Recent developments and future predictions suggest that vaccinations will soon be developed with the dual goal of reducing the patient's susceptibility to illness while simultaneously strengthening their immune system. Many clinical and preclinical studies are now investigating the effectiveness of immunotherapy in slowing the progression of cervical cancer. The field of immunotherapy is expected to witness more progress toward improving outcomes. Immunotherapies landscape and associated inhibitors for the treatment of Cervical Cancer.

Fas/FasL and Complement Activation are Associated with Chronic Active Epstein-Barr Virus Hepatitis

BACKGROUND AND AIMS

Chronic active Epstein-Barr virus hepatitis (CAEBVH) is a rare and highly lethal disease characterized by hepatitis and hepatomegaly. This study aimed to investigate the clinicopathological features and pathogenic mechanisms of CAEBVH.

METHODS

Ten patients with confirmed Epstein-Barr virus hepatitis infection were enrolled. The clinicopathological characteristics of these patients were summarized and analyzed. Flow cytometry was utilized to detect peripheral blood immune cell phenotypes and whole exome sequencing was used to explore pathogenic genetic mechanisms. Lastly, immunohistochemical staining was employed to verify pathogenic mechanisms.

RESULTS

Clinical features observed in all Epstein-Barr virus hepatitis patients included fever (7/10), splenomegaly (10/10), hepatomegaly (9/10), abnormal liver function (8/10), and CD8⁺ T cell lymphopenia (6/7). Hematoxylin and eosin staining revealed lymphocytic infiltration in the liver. Positive Epstein-Barr virus-encoded small RNA in-situ hybridization (EBER-ISH) of lymphocytes of liver tissues was noted. Whole exome sequencing indicated that cytotoxic T lymphocytes and the complement system were involved. The expression of CD8, Fas, FasL, and Caspase-8 expression as well as apoptotic markers was enhanced in the Epstein-Barr virus hepatitis group relative to the controls (p<0.05). Lastly, Complement 1q and complement 3d expression, were higher in CAEBVH patients relative to controls (p<0.05).

CONCLUSIONS

CAEBVH patients developed fever, hepatosplenomegaly, and lymphadenopathy. Histopathological changes were a diffuse lymphocytic sinusoidal infiltrate with EBER-ISH positivity. Fas/FasL and complement activation were involved in CAEBVH patients.

Virus against virus: strategies for using adenovirus vectors in the treatment of HPV-induced cervical cancer

Although most human papillomavirus (HPV) infections are harmless, persistent infection with high-risk types of HPV is known to be the leading cause of cervical cancer. Following the infection of the epithelium and integration into the host genome, the oncogenic proteins E6 and E7 disrupt cell cycle control by inducing p53 and retinoblastoma (Rb) degradation. Despite the FDA approval of prophylactic vaccines, there are still issues with cervical cancer treatment; thus, many therapeutic approaches have been developed to date. Due to strong immunogenicity, a high capacity for packaging foreign DNA, safety, and the ability to infect a myriad of cells, adenoviruses have drawn attention of researchers. Adenovirus vectors have been used for different purposes, including as oncolytic agents to kill cancer cells, carrier for RNA interference to block oncoproteins expression, vaccines for eliciting immune responses, especially in cytotoxic T lymphocytes (CTLs), and gene therapy vehicles for restoring p53 and Rb function.

Cervical Cancer Immunotherapy: Facts and Hopes

It is a sad fact that despite being almost completely preventable through human papillomavirus (HPV) vaccination and screening, cervical cancer remains the fourth most common cancer to affect women worldwide. Persistent high-risk HPV (hrHPV) infection is the primary etiologic factor for cervical cancer. Upward of 70% of cases are driven by HPV types 16 and 18, with a dozen other hrHPVs associated with the remainder of cases. Current standard-of-care treatments include radiotherapy, chemotherapy, and/or surgical resection. However, they have significant side effects and limited efficacy against advanced disease. There are a few treatment options for recurrent or metastatic cases. Immunotherapy offers new hope, as demonstrated by the recent approval of programmed cell death protein 1-blocking antibody for recurrent or metastatic disease. This might be augmented by combination with antigen-specific immunotherapy approaches, such as vaccines or adoptive cell transfer, to enhance the host cellular immune response targeting HPV-positive cancer cells. As cervical cancer progresses, it can foster an immunosuppressive microenvironment and counteract host anticancer immunity. Thus, approaches to reverse suppressive immune environments and bolster effector T-cell functioning are likely to enhance the success of such cervical cancer immunotherapy. The success of nonspecific immunostimulants like imiquimod against genital warts also suggest the possibility of utilizing these immunotherapeutic strategies in cervical cancer prevention to treat precursor lesions (cervical intraepithelial neoplasia) and persistent hrHPV infections against which the licensed prophylactic HPV vaccines have no efficacy. Here, we review the progress and challenges in the development of immunotherapeutic approaches for the prevention and treatment of cervical cancer.

Vaccination Strategies for the Control and Treatment of HPV Infection and HPV-Associated Cancer

Human papillomavirus (HPV) is the most common sexually transmitted infection, currently affecting close to 80 million Americans. Importantly, HPV infection is recognized as the etiologic factor for numerous cancers, including cervical, vulval, vaginal, penile, anal, and a subset of oropharyngeal cancers. The prevalence of HPV infection and its associated diseases are a significant problem, affecting millions of individuals worldwide. Likewise, the incidence of HPV infection poses a significant burden on individuals and the broader healthcare system. Between 2011 and 2015, there were an estimated 42,700 new cases of HPV-associated cancers each year in the United States alone. Similarly, the global burden of HPV is high, with around 630,000 new cases of HPV-associated cancer occurring each year. In the last decade, a total of three preventive major capsid protein (L1) virus-like particle-based HPV vaccines have been licensed and brought to market as a means to prevent the spread of HPV infection. These prophylactic vaccines have been demonstrated to be safe and efficacious in preventing HPV infection. The most recent iteration of the preventive HPV vaccine, a nanovalent, L1-VLP vaccine, protects against a total of nine HPV types (seven high-risk and two low-risk HPV types), including the high-risk types HPV16 and HPV18, which are responsible for causing the majority of HPV-associated cancers. Although current prophylactic HPV vaccines have demonstrated huge success in preventing infection, existing barriers to vaccine acquisition have limited their widespread use, especially in low- and middle-income countries, where the burden of HPV-associated diseases is highest. Prophylactic vaccines are unable to provide protection to individuals with existing HPV infections or HPV-associated diseases. Instead, therapeutic HPV vaccines capable of generating T cell-mediated immunity against HPV infection and associated diseases are needed to ameliorate the burden of disease in individuals with existing HPV infection. To generate a cell-mediated immune response against HPV, most therapeutic vaccines target HPV oncoproteins E6 and E7. Several types of therapeutic HPV vaccine candidates have been developed including live-vector, protein, peptide, dendritic cell, and DNA-based vaccines. This chapter will review the commercially available prophylactic HPV vaccines and discuss the recent progress in the development of therapeutic HPV vaccines.

Enhanced Human T Lymphocyte Antigen Priming by Cytokine-Matured Dendritic Cells Overexpressing Bcl-2 and IL-12

Dendritic cell (DC)-based vaccination is a promising immunotherapeutic strategy for cancer. However, clinical trials have shown only limited efficacy, suggesting the need to optimize protocols for human DC vaccine preparation. In this study, we systemically compared five different human DC vaccine maturation protocols used in clinical trials: (1) a four-cytokine cocktail (TNF-α, IL-6, IL-1β, and PGE2); (2) an α-DC-cytokine cocktail (TNF-α, IL-1β, IFN-α, IFN-γ, and poly I:C); (3) lipopolysaccharide (LPS)/IFN-γ; (4) TNF-α and PGE2; and (5) TriMix (mRNAs encoding CD40L, CD70, and constitutively active Toll-like receptor 4 electroporated into immature DCs). We found that the four-cytokine cocktail induced high levels of costimulatory and HLA molecules, as well as CCR7, in DCs. Mature DCs (mDCs) matured with the four-cytokine cocktail had higher viability than those obtained with the other protocols. Based on these features, we chose the four-cytokine cocktail protocol to further improve the immunizing capability of DCs by introducing exogenous genes. We showed that introducing exogenous Bcl-2 increased DC survival. Furthermore, introducing IL-12p70 rescued the inhibition of IL-12 secretion by PGE2 without impairing the DC phenotype. Introducing both Bcl-2 and IL-12p70 mRNAs into DCs induced enhanced cytomegalovirus pp65-specific CD8⁺ T cells secreting IFN-γ and TNF-α. Taken together, our data suggest that DC matured by the four-cytokine cocktail combined with exogenous Bcl-2 and IL-12p70 gene expression represents a promising approach for clinical applications in cancer immunotherapy.

Current strategies against persistent human papillomavirus infection (Review)

Human papillomavirus (HPV) is the most common sexually transmitted infection, exhibiting a tropism for the epidermis and mucosae. The link between persistent HPV infection and malignancies involving the anogenital tract as well as the head and neck has been well‑established, and it is estimated that HPV‑related cancers involving various anatomical sites account for 4.5% of all human cancers. Current prophylactic vaccines against HPV have enabled the prevention of associated malignancies. However, the sizeable population base of current infection in whom prophylactic vaccines are not applicable, certain high‑risk HPV types not included in vaccines, and the vast susceptible population in developing countries who do not have access to the costly prophylactic vaccines, put forward an imperative need for effective therapies targeting persistent infection. In this article, the life cycle of HPV, the mechanisms facilitating HPV evasion of recognition and clearance by the host immune system, and the promising therapeutic strategies currently under investigation, particularly antiviral drugs and therapeutic vaccines, are reviewed.

Induction of memory-like dendritic cell responses in vivo

Dendritic cells (DCs), a vital component of the innate immune system, are considered to lack antigen specificity and be devoid of immunological memory. Strategies that can induce memory-like responses from innate cells can be utilized to elicit protective immunity in immune deficient persons. Here we utilize an experimental immunization strategy to modulate DC inflammatory and memory-like responses against an opportunistic fungal pathogen that causes significant disease in immunocompromised individuals. Our results show that DCs isolated from protectively immunized mice exhibit enhanced transcriptional activation of interferon and immune signaling pathways. We also show long-term memory-like cytokine responses upon subsequent challenge with the fungal pathogen that are abrogated with inhibitors of specific histone modifications. Altogether, our study demonstrates that immunization strategies can be designed to elicit memory-like DC responses against infectious disease.

Wormley and colleagues present data showing that vaccine strategies can be devised to prime dendritic cells to respond in a memory-like fashion upon subsequent exposure to a pathogen.

Regulatory perspective on in vitro potency assays for human dendritic cells used in anti-tumor immunotherapy

Dendritic cells (DCs) are key connectors between the innate and adaptive immune system and have an important role in modulating other immune cells. Therefore, their therapeutic application to steer immune responses is considered in various disorders, including cancer. Due to differences in the cell source and manufacturing process, each DC medicinal product is unique. Consequently, release tests to ensure consistent quality need to be product-specific. Although general guidance concerning quality control testing of cell-based therapies is available, cell type-specific regulation is still limited. Especially guidance related to potency testing is needed, because developing an in vitro assay measuring cell properties relevant for in vivo functionality is challenging. In this review, we provide DC-specific guidance for development of in vitro potency assays for characterisation and release. We present a broad overview of in vitro potency assays suggested for DC products to determine their anti-tumor functionality. Several advantages and limitations of these assays are discussed. Also, we provide some points to consider for selection and design of a potency test. The ideal functionality assay for anti-tumor products evaluates the capacity of DCs to stimulate antigen-specific T cells. Because this approach may not be feasible for release, use of surrogate potency markers could be considered, provided that these markers are sufficiently linked to the in vivo DC biological activity and clinical response. Further elucidation of the involvement of specific DC subsets in anti-tumor responses will result in improved manufacturing processes for DC-based products and should be considered during potency assay development.

Therapeutic vaccines for high-risk HPV-associated diseases

Cancer is the second leading cause of death worldwide, and it is estimated that Human papillomavirus (HPV) related cancers account for 5% of all human cancers. Current HPV vaccines are extremely effective at preventing infection and neoplastic disease; however, they are prophylactic and do not clear established infections. Therapeutic vaccines which trigger cell-mediated immune responses for the treatment of established infections and malignancies are therefore required. The E6 and E7 early genes are ideal targets for vaccine therapy due to their role in disruption of the cell cycle and their constitutive expression in premalignant and malignant tissues. Several strategies have been investigated for the development of therapeutic vaccines, including live-vector, nucleic acid, peptide, protein-based and cell-based vaccines as well as combinatorial approaches, with several vaccine candidates progressing to clinical trials. With the current understanding of the HPV life cycle, molecular mechanisms of infection, carcinogenesis, tumour biology, the tumour microenvironment and immune response mechanisms, an approved HPV therapeutic vaccine seems to be a goal not far from being achieved. In this article, the status of therapeutic HPV vaccines in clinical trials are reviewed, and the potential for plant-based vaccine production platforms described.

Strategies to Genetically Modulate Dendritic Cells to Potentiate Anti-Tumor Responses in Hematologic Malignancies

Dendritic cell (DC) vaccination has been investigated as a potential strategy to target hematologic malignancies, while generating sustained immunological responses to control potential future relapse. Nonetheless, few clinical trials have shown robust long-term efficacy. It has been suggested that a combination of surmountable shortcomings, such as selection of utilized DC subsets, DC loading and maturation strategies, as well as tumor-induced immunosuppression may be targeted to maximize anti-tumor responses of DC vaccines. Generation of DC from CD34+ hematopoietic stem and progenitor cells (HSPCs) may provide potential in patients undergoing allogeneic HSPC transplantations for hematologic malignancies. CD34+ HSPC from the graft can be genetically modified to optimize antigen presentation and to provide sufficient T cell stimulatory signals. We here describe beneficial (gene)-modifications that can be implemented in various processes in T cell activation by DC, among which major histocompatibility complex (MHC) class I and MHC class II presentation, DC maturation and migration, cross-presentation, co-stimulation, and immunosuppression to improve anti-tumor responses.

Gene-modified dendritic cell vaccines for cancer

Dendritic cell (DC) vaccines are an immunotherapeutic approach to cancer treatment that use the antigen-presentation machinery of DCs to activate an endogenous anti-tumor response. In this treatment strategy, DCs are cultured ex vivo, exposed to tumor antigens and administered to the patient. The ex vivo culturing provides a unique and powerful opportunity to modify and enhance the DCs. As such, a variety of genetic engineering approaches have been employed to optimize DC vaccines, including the introduction of messenger RNA and small interfering RNA, viral gene transduction, and even fusion with whole tumor cells. In general, these modifications aim to improve targeting, enhance immunogenicity, and reduce susceptibility to the immunosuppressive tumor microenvironment. It has been demonstrated that several of these modifications can be employed in tandem, allowing for fine-tuning and optimization of the DC vaccine across multiple metrics. Thus, the application of genetic engineering techniques to the dendritic cell vaccine platform has the potential to greatly enhance its efficacy in the clinic.

Tracking dendritic cell migration into lymph nodes by using a novel PET probe 18F-tetrafluoroborate for sodium/iodide symporter

BACKGROUND

Recently, ¹⁸F-tetrafluoroborate (TFB) was used as a substrate for the human sodium/iodide symporter (hNIS) reporter gene. This study evaluated the feasibility of performing molecular-genetic imaging by using the new radiotracer (¹⁸F-TFB) for the hNIS gene, to track dendritic cell (DC) migration in live mice. A murine dendritic cell line (DC2.4) co-expressing the hNIS and effluc genes (DC/NF) was established. To confirm the functional cellular expression of both effluc and NIS in the inoculated DC/NF cells by bio-medical imaging, combined bioluminescence imaging (BLI) and ¹⁸F-TFB positron emission tomography/computed tomography (PET/CT) imaging was performed after intramuscular injection with parental DCs and DC/NF cells. For DC-tracking, parental DCs or DC/NF cells were injected in the left or right mouse footpad, respectively, and ¹⁸F-TFB PET/CT and BLI were performed to monitor these cells in live mice.

RESULTS

In vivo PET/CT and BLI showed a clear signal in DC/NF injection sites but not in parental DC injection sites. The signal intensity in DC/NF cells was correlated with time. In vivo ¹⁸F-TFB PET/CT imaging showed higher radiotracer activity in the draining popliteal lymph nodes (DPLNs) in DC/NF injection sites than those in DC injection sites on day 2. BLI also showed DC/NF cell migration to the DPLNs on day 2 after the injection.

CONCLUSIONS

Migration of DCs to the lymph nodes was successfully monitored using ¹⁸F-TFB PET/CT imaging of the NIS gene and optical imaging of the effluc gene in live mice. These data support the feasibility of using ¹⁸F-TFB as a substrate for hNIS reporter gene imaging to track the migration of DCs to the lymph nodes in live animals. The use of ¹⁸F-TFB may facilitate enhanced PET imaging of the hNIS reporter gene in small animals and humans in future studies.

The current state of therapeutic and T cell-based vaccines against human papillomaviruses

Human papillomavirus (HPV) is known to be a necessary factor for many gynecologic malignancies and is also associated with a subset of head and neck malignancies. This knowledge has created the opportunity to control these HPV-associated cancers through vaccination. However, despite the availability of prophylactic HPV vaccines, HPV infections remain extremely common worldwide. In addition, while prophylactic HPV vaccines have been effective in preventing infection, they are ineffective at clearing pre-existing HPV infections. Thus, there is an urgent need for therapeutic and T cell-based vaccines to treat existing HPV infections and HPV-associated lesions and cancers. Unlike prophylactic vaccines, which generate neutralizing antibodies, therapeutic, and T cell-based vaccines enhance cell-mediated immunity against HPV antigens. Our review will cover various therapeutic and T cell-based vaccines in development for the treatment of HPV-associated diseases. Furthermore, we review the strategies to enhance the efficacy of therapeutic vaccines and the latest clinical trials on therapeutic and T cell-based HPV vaccines.

Perspectives for therapeutic HPV vaccine development

Background

Human papillomavirus (HPV) infections and associated diseases remain a serious burden worldwide. It is now clear that HPV serves as the etiological factor and biologic carcinogen for HPV-associated lesions and cancers. Although preventative HPV vaccines are available, these vaccines do not induce strong therapeutic effects against established HPV infections and lesions. These concerns create a critical need for the development of therapeutic strategies, such as vaccines, to treat these existing infections and diseases.

Main Body

Unlike preventative vaccines, therapeutic vaccines aim to generate cell-mediated immunity. HPV oncoproteins E6 and E7 are responsible for the malignant progression of HPV-associated diseases and are consistently expressed in HPV-associated diseases and cancer lesions; therefore, they serve as ideal targets for the development of therapeutic HPV vaccines. In this review we revisit therapeutic HPV vaccines that utilize this knowledge to treat HPV-associated lesions and cancers, with a focus on the findings of recent therapeutic HPV vaccine clinical trials.

Conclusion

Great progress has been made to develop and improve novel therapeutic HPV vaccines to treat existing HPV infections and diseases; however, there is still much work to be done. We believe that therapeutic HPV vaccines have the potential to become a widely available and successful therapy to treat HPV and HPV-associated diseases in the near future.

The combination of Pleurotus ferulae water extract and CpG-ODN enhances the immune responses and antitumor efficacy of HPV peptides pulsed dendritic cell-based vaccine

Our previous study reported that the combination of Pleurotus ferulae water extract (PFWE) and CpG (PFWE+CpG) enhanced the maturation and function of dendritic cells (DCs). Here, we investigated the effects of PFWE+CpG on the immune responses and antitumor efficacy of DC-based vaccine. We observed that all of HPV E6 and E7 peptides pulsed DCs (HPV-immature DCs, HPV+PFWE-, +CpG- or +PFWE+CpG-DCs) induced antigen-specific CD8(+) T cell responses and HPV+PFWE+CpG-DCs induced highest level of CD8(+) T cell responses. The antitumor efficacy of HPV-DCs vaccines was evaluated in TC-1 tumor mouse model. The early therapeutic study showed that HPV+PFWE-, +CpG- and +PFWE+CpG-DCs greatly inhibited tumor growth. Moreover, HPV+PFWE+CpG-DCs controlled tumor growth at a faster rate compared to other groups. These three groups induced HPV-specific CD8(+) T cell responses and significantly decreased the frequencies of induced regulatory T cells (iTregs: CD4(+)CD25(-)Fopx3(+)). However, only HPV+PFWE+CpG-DCs significantly decreased the frequency of natural Tregs (nTregs: CD4(+)CD25(+)Fopx3(+)). Furthermore, HPV+PFWE+CpG-DCs also significantly inhibited tumor growth in the late therapeutic study. The results showed that PFWE+CpG enhanced the immune responses and antitumor efficacy of DC-based vaccine, suggesting that PFWE+CpG might be the potential candidate for the generation of clinical-grade mature DCs.

Current state in the development of candidate therapeutic HPV vaccines

The identification of human papillomavirus (HPV) as an etiological factor for HPV-associated malignancies creates the opportunity to control these cancers through vaccination. Currently, available preventive HPV vaccines have not yet demonstrated strong evidences for therapeutic effects against established HPV infections and lesions. Furthermore, HPV infections remain extremely common. Thus, there is urgent need for therapeutic vaccines to treat existing HPV infections and HPV-associated diseases. Therapeutic vaccines differ from preventive vaccines in that they are aimed at generating cell-mediated immunity rather than neutralizing antibodies. The HPV-encoded early proteins, especially oncoproteins E6 and E7, form ideal targets for therapeutic HPV vaccines since they are consistently expressed in HPV-associated malignancies and precancerous lesions, playing crucial roles in the generation and maintenance of HPV-associated disease. Our review will cover various therapeutic vaccines in development for the treatment of HPV-associated lesions and cancers. Furthermore, we review strategies to enhance vaccine efficacy and the latest clinical trials on therapeutic HPV vaccines.

The siRNA cocktail targeting interleukin 10 receptor and transforming growth factor-β receptor on dendritic cells potentiates tumour antigen-specific CD8(+) T cell immunity

Dendritic cells (DCs) are promising therapeutic agents in the field of cancer immunotherapy due to their intrinsic immune-priming capacity. The potency of DCs, however, is readily attenuated immediately after their administration in patients as tumours and various immune cells, including DCs, produce various immunosuppressive factors such as interleukin (IL)-10 and transforming growth factor (TGF)-β that hamper the function of DCs. In this study, we used small interfering RNA (siRNA) to silence the expression of endogenous molecules in DCs, which can sense immunosuppressive factors. Among the siRNAs targeting various immunosuppressive molecules, we observed that DCs transfected with siRNA targeting IL-10 receptor alpha (siIL-10RA) initiated the strongest antigen-specific CD8(+) T cell immune responses. The potency of siIL-10RA was enhanced further by combining it with siRNA targeting TGF-β receptor (siTGF-βR), which was the next best option during the screening of this study, or the previously selected immunoadjuvant siRNA targeting phosphatase and tensin homologue deleted on chromosome 10 (PTEN) or Bcl-2-like protein 11 (BIM). In the midst of sorting out the siRNA cocktails, the cocktail of siIL-10RA and siTGF-βR generated the strongest antigen-specific CD8(+) T cell immunity. Concordantly, the knock-down of both IL-10RA and TGF-βR in DCs induced the strongest anti-tumour effects in the TC-1 P0 tumour model, a cervical cancer model expressing the human papillomavirus (HPV)-16 E7 antigen, and even in the immune-resistant TC-1 (P3) tumour model that secretes more IL-10 and TGF-β than the parental tumour cells (TC-1 P0). These results provide the groundwork for future clinical development of the siRNA cocktail-mediated strategy by co-targeting immunosuppressive molecules to enhance the potency of DC-based vaccines.

Tracking of dendritic cell migration into lymph nodes using molecular imaging with sodium iodide symporter and enhanced firefly luciferase genes

We sought to evaluate the feasibility of molecular imaging using the human sodium iodide symporter (hNIS) gene as a reporter, in addition to the enhanced firefly luciferase (effluc) gene, for tracking dendritic cell (DCs) migration in living mice. A murine dendritic cell line (DC2.4) co-expressing hNIS and effluc genes (DC/NF) was established. For the DC-tracking study, mice received either parental DCs or DC/NF cells in the left or right footpad, respectively, and combined I-124 PET/CT and bioluminescence imaging (BLI) were performed. In vivo PET/CT imaging with I-124 revealed higher activity of the radiotracer in the draining popliteal lymph nodes (DPLN) of the DC/NF injection site at day 1 than DC injection site (p < 0.05). The uptake value further increased at day 4 (p < 0.005). BLI also demonstrated migration of DC/NF cells to the DPLNs at day 1 post-injection, and signals at the DPLNs were much higher at day 4. These data support the feasibility of hNIS reporter gene imaging in the tracking of DC migration to lymphoid organs in living mice. DCs expressing the NIS reporter gene could be a useful tool to optimize various strategies of cell-based immunotherapy.

A polymeric conjugate foreignizing tumor cells for targeted immunotherapy in vivo

Antigen-specific CD8(+) cytotoxic T lymphocytes (CTLs) are key elements of immunological rejection in transplantation as well as cancer immunotherapy. Most tumors, however, are not immunologically rejected because they have self antigens, which are not recognized as the foreigner by CTLs. In this study, we hypothesized that "foreignizing" tumor cells by delivering non-self foreign antigens into the tumors would result in rejection by foreign antigen-reactive CTLs. As the model system to foreignize the tumors, we prepared a polymeric conjugate consisting of hyaluronic acid as the CD44(+) tumor-targeting ligand and ovalbumin (OVA) as a foreign antigen. When the conjugate was treated with CD44(high) TC-1 tumor cells, it was effectively taken up and allowed for displaying of antigenic OVA257-264 peptide at MHC class I on the surface of the cells. In addition, the conjugate was effectively accumulated into tumor tissue after its systemic administration to mice which are immunized with a vaccine for a vaccinia virus expressing OVA to generate OVA257-264 specific CTLs, resulting in substantial inhibition of tumor growth. Overall, these results suggest that the polymeric conjugates bearing foreign antigens may be innovative and promising cancer immunotherapeutic agents by foreignizing tumor cells, leading to immunological rejection.

Apoptosis inhibitor-5 overexpression is associated with tumor progression and poor prognosis in patients with cervical cancer

BACKGROUND

The apoptosis inhibitor-5 (API5), anti-apoptosis protein, is considered a key molecule in the tumor progression and malignant phenotype of tumor cells. Here, we investigated API5 expression in cervical cancer, its clinical significance, and its relationship with phosphorylated extracellular signal-regulated kinase 1 and 2 (pERK1/2) in development and progression of cervical cancer.

METHODS

API5 effects on cell growth were assessed in cervical cancer cell lines. API5 and pERK1/2 immunohistochemical staining were performed on a cervical cancer tissue microarray consisting of 173 primary cervical cancers, 306 cervical intraepithelial neoplasias (CINs), and 429 matched normal tissues.

RESULTS

API5 overexpression promoted cell proliferation and colony formation in CaSki cells, whereas API5 knockdown inhibited the both properties in HeLa cells. Immunohistochemical staining showed that API5 expression increased during the normal to tumor transition of cervical carcinoma (P < 0.001), and this increased expression was significantly associated with tumor stage (P = 0.004), tumor grade (P < 0.001), and chemo-radiation response (P = 0.004). API5 expression levels were positively associated with pERK1/2 in cervical cancer (P < 0.001) and high grade CIN (P = 0.031). In multivariate analysis, API5+ (P = 0.039) and combined API5+/pERK1/2+ (P = 0.032) were independent prognostic factors for overall survival.

CONCLUSIONS

API5 expression is associated with pERK1/2 in a subset of cervical cancer patients and its expression predicts poor overall survival, supporting that API5 may be a promising novel target for therapeutic interventions.

Histone deacetylase inhibitor sensitizes apoptosis-resistant melanomas to cytotoxic human T lymphocytes through regulation of TRAIL/DR5 pathway

Modern immune therapies (PD-1/PD-L1 and CTLA-4 checkpoints blockade and adoptive cell transfer) have remarkably improved the response rates of metastatic melanoma. These modalities rely on the killing potential of CTL as proximal mediator of antimelanoma responses. Mechanisms of tumor resistance to and the predominant cytotoxic pathway(s) used by melanoma-reactive CTL are important outcome determinants. We hypothesized that downmodulation of death receptors (DRs) in addition to aberrant apoptotic signaling might confer resistance to death signals delivered by CTL. To test these two hypotheses, we used an in vitro model of MART CTL-resistant melanoma sublines. TCR-transgenic and patient-derived CTLs used the TRAIL cytotoxic pathway through DR5. Furthermore, recombinant human TRAIL and drozitumab (anti-DR5 agonistic mAb) were used to explicitly verify the contribution of the DR5/TRAIL pathway in killing melanomas. CTL resistance was due to DR5 downregulation and an inverted ratio of pro- to antiapoptotic molecules, both of which were reversed by the histone deacetylase inhibitor suberoylanilide hydroxanic acid. Apoptosis negative (c-IAP-2 and Bcl-xL) and positive (DR5) regulators were potential incriminators partly regulating CTL sensitivity. These preclinical findings suggest that exposure to this chromatin remodeling drug of immune-resistant melanomas can skew toward an intracellular proapoptotic milieu, increase DR expression, and overcome acquired immune resistance.

Improving the in vivo persistence, distribution and function of cytotoxic T lymphocytes by inhibiting the tumor immunosuppressive microenvironment

Adoptive cell transfer immunotherapy of malignant tumors has the problem of symbiosis between effector cells and tumor cells, a short in vivo residence time, and a poor killing efficiency of effector cells. Thus, releasing effector cells from the cancer immunosuppressive microenvironment and improving their effective time and functional status in vivo would seem to be ideal strategies for facilitating immunotherapy. Low-dose cyclophosphamide administration can effectively break immunotolerance by inhibiting regulatory T cells. In the present study, in order to verify whether the persistence, distribution and function of effector cells can be improved by inhibiting immunosuppressive microenvironment, low-dose cyclophosphamide was previously intraperitoneally injected into melanoma-bearing C57BL/6 mice, thereafter, CFSE-labeled cytotoxic T lymphocytes were transfused intravenously, and their effective time, distributive pattern, and killing efficiency in different groups were observed by measuring the fluorescence intensity and cell cycle of cytotoxic T lymphocytes distributed in various organs, in comparison with tumor growth. We found down-regulating Tregs in vivo can simultaneously reduce the levels of interleukin-10 and transforming growth factor-β. Migration and distribution of cytotoxic T lymphocytes in vivo was found to vary with time. Inhibition of immunotolerance can significantly improve the persistence, distribution, and function of cytotoxic T lymphocytes. Correspondingly, significantly higher secretion of perforin, granzyme B, IL-2, and IFN-γ in tumor tissues with decreased tumor growth was seen in the cyclophosphamide injection group than in the control group. Our study may provide useful information on the cyclophosphamide-mediated mechanism for facilitating tumor immunotherapy by inhibiting the immunosuppressive tumor microenvironment.

Targeted treatments for cervical cancer: a review

Cervical cancer is the second most common cause of cancer death in women worldwide and the development of new diagnosis, prognostic, and treatment strategies merits special attention. Although surgery and chemoradiotherapy can cure 80%–95% of women with early stage cancer, the recurrent and metastatic disease remains a major cause of cancer death. Many efforts have been made to design new drugs and develop gene therapies to treat cervical cancer. In recent decades, research on treatment strategies has proposed several options, including the role of HPV E6 and E7 oncogenes, which are retained and expressed in most cervical cancers and whose respective oncoproteins are critical to the induction and maintenance of the malignant phenotype. Other efforts have been focused on antitumor immunotherapy strategies. It is known that during the development of cervical cancer, a cascade of abnormal events is induced, including disruption of cellular cycle control, perturbation of antitumor immune response, alteration of gene expression, and deregulation of microRNA expression. Thus, in this review article we discuss potential targets for the treatment of cervical cancer associated with HPV infection, with special attention to immunotherapy approaches, clinical trials, siRNA molecules, and their implications as gene therapy strategies against cervical cancer development.

Nanog signaling in cancer promotes stem-like phenotype and immune evasion

Adaptation of tumor cells to the host is a major cause of cancer progression, failure of therapy, and ultimately death. Immune selection drives this adaptation in human cancer by enriching tumor cells with a cancer stem cell-like (CSC-like) phenotype that makes them resistant to CTL-mediated apoptosis; however, the mechanisms that mediate CSC maintenance and proliferation are largely unknown. Here, we report that CTL-mediated immune selection drives the evolution of tumor cells toward a CSC-like phenotype and that the CSC-like phenotype arises through the Akt signaling pathway via transcriptional induction of Tcl1a by Nanog. Furthermore, we found that hyperactivation of the Nanog/Tcl1a/Akt signaling axis was conserved across multiple types of human cancer. Inhibition of Nanog in a murine model of colon cancer rendered tumor cells susceptible to immune-mediated clearance and led to successful, long-term control of the disease. Our findings establish a firm link among immune selection, disease progression, and the development of a stem-like tumor phenotype in human cancer and implicate the Nanog/Tcl1a/Akt pathway as a central molecular target in this process.

Inhibition of mechanistic target of rapamycin promotes dendritic cell activation and enhances therapeutic autologous vaccination in mice

Dendritic cells (DCs) are potent inducers of T cell immunity, and autologous DC vaccination holds promise for the treatment of cancers and chronic infectious diseases. In practice, however, therapeutic vaccines of this type have had mixed success. In this article, we show that brief exposure to inhibitors of mechanistic target of rapamycin (mTOR) in DCs during the period that they are responding to TLR agonists makes them particularly potent activators of naive CD8+ T cells and able to enhance control of B16 melanoma in a therapeutic autologous vaccination model in the mouse. The improved performance of DCs in which mTOR has been inhibited is correlated with an extended life span after activation and prolonged, increased expression of costimulatory molecules. Therapeutic autologous vaccination with DCs treated with TLR agonists plus the mTOR inhibitor rapamycin results in improved generation of Ag-specific CD8+ T cells in vivo and improved antitumor immunity compared with that observed with DCs treated with TLR agonists alone. These findings define mTOR as a molecular target for augmenting DC survival and activation, and document a novel pharmacologic approach for enhancing the efficacy of therapeutic autologous DC vaccination.

Regulation of CD28 expression on umbilical cord blood and adult peripheral blood CD8+ T cells by interleukin(IL)-15/IL-21

Interleukin (IL)-15 and IL-21, both belonging to common γ-chain-signaling cytokine family, have an important role to maintain homeostatic proliferation of CD8(+) T cells. CD28, an essential co-stimulatory molecule on T cells, may be a marker of replicative senescence. We investigated the effect of IL-15 and IL-21, alone or in combination, on activation, apoptosis, cytokine production and cytotoxic function of magnetic bead purified umbilical cord blood (UCB) and adult peripheral blood (APB) CD8(+) T cells with regards to their CD28 expression. We established that (1) IL-15-induced CD8(+) T cell proliferation was associated with a preferential expansion of CD28(-) population in UCB, which could be partially counteracted by IL-21; (2) UCB CD8(+) T cells were more readily responsive to IL-15 compared to their adult counterparts in terms of CD69 expression, with the majority of CD69-bearing CD8(+) T cells were CD28(-); (3) IL-21 further promoted interferon-gamma, but not tumor necrosis factor-alpha production from IL-15 treated CD8(+) T cells; (4) IL-21 also synergized with IL-15 to enhance perforin and granzyme B expression of CD8(+) T cells, especially in APB CD8(+)CD28(-) subsets; (5) IL-21 resulted in CD8(+) T cells apoptosis both in APB and UCB cells, mainly in CD8(+)CD28(-) subsets. Taken together, we demonstrate differential IL-15/IL-21 response in UCB CD8(+) T cells with regards to CD28 expression. Our results suggest that combining IL-21 and IL-15 immunotherapy may be better than IL-15 alone to ameliorate graft-versus-host disease while preserving antitumor effect in the post-UCB transplantation period.

Regulation of Immune Responses by Spontaneous and T cell-mediated Dendritic Cell Death

In response to antigen stimulations, cells in the immune system undergo dynamic activation, differentiation, expansion and turnover. Programmed cell death is important for maintaining homeostasis of different cell types in the immune system. Dendritic cells (DCs) are a heterogeneous population of antigen presenting cells that capture, process and present antigens to stimulate lymphocytes. DCs have also emerged as major regulators of both innate and adaptive immune responses. Conventional myeloid DCs are relatively short-lived compared to lymphocytes in lymphoid organs. Mitochondrion-dependent apoptosis governed by Bcl-2 family members plays a major role in regulating spontaneous DC turnover. Killing of DCs by antigen-specific T cells also provides a negative feedback mechanism to restrict the duration and the scope of immune responses. Defects in cell death in DCs lead to DC accumulation, resulting in overactivation of lymphocytes and the development of autoimmunity in mice. Programmed cell death in DCs may play essential roles in the regulation of the duration and magnitude of immune responses, and in the protection against autoimmunity and uncontrolled inflammation.

Combined E7-dendritic cell-based immunotherapy and human sodium/iodide symporter radioiodine gene therapy with monitoring of antitumor effects by bioluminescent imaging in a mouse model of uterine cervical cancer

Using a uterine cervical cancer cell line expressing human papillomavirus (HPV) 16 E7 antigen and bioluminescent imaging (BLI), we evaluated the therapeutic potential of combined immunotherapy using transfected dendritic cells (DC-E7) and human sodium/iodide symporter (hNIS) radioiodine gene therapy in a xenograft animal cancer model. Dendritic cells expressing either E7 antigen (DC-E7) or no-insert (DC-no insert) were made for immunization materials, and murine uterine cervical cancer cell line coexpressing E7, firefly luciferase, hNIS, and EGFP genes (TC-1/FNG) were prepared for the animal tumor model. C57BL/6 mice were divided into five therapy groups (phosphate-buffered saline [PBS], DC-no insert, DC-E7, I-131, and DC-E7+I-131 groups). Single therapy with either DC-E7 or I-131 induced greater retardation in tumor growth compared with PBS or DC-no insert groups, and it resulted in some tumor-free mice (DC-E7 and I-131 groups, 40% and 20%, respectively). Combination therapy with DC-E7 and I-131 dramatically inhibited tumor growth, thus causing complete disappearance of tumors in all mice, and these effects were further confirmed by BLI in vivo. In conclusion, complete disappearance of the tumor was achieved with combined DC-E7 vaccination and hNIS radioiodine gene therapy in a mouse model with E7-expressing uterine cervical cancer, and serial BLIs successfully demonstrated antitumor effects in vivo.

New Approaches to Immunotherapy for HPV Associated Cancers

Cervical cancer is the second most common cancer of women worldwide and is the first cancer shown to be entirely induced by a virus, the human papillomavirus (HPV, major oncogenic genotypes HPV-16 and -18). Two recently developed prophylactic cervical cancer vaccines, using virus-like particles (VLP) technology, have the potential to prevent a large proportion of cervical cancer associated with HPV infection and to ensure long-term protection. However, prophylactic HPV vaccines do not have therapeutic effects against pre-existing HPV infections and do not prevent their progression to HPV-associated malignancy. In animal models, therapeutic vaccines for persisting HPV infection can eliminate transplantable tumors expressing HPV antigens, but are of limited efficacy in inducing rejection of skin grafts expressing the same antigens. In humans, clinical trials have reported successful immunotherapy of HPV lesions, providing hope and further interest. This review discusses possible new approaches to immunotherapy for HPV associated cancer, based on recent advances in our knowledge of the immunobiology of HPV infection, of epithelial immunology and of immunoregulation, with a brief overview on previous and current HPV vaccine clinical trials.

Blocking the immunosuppressive axis with small interfering RNA targeting interleukin (IL)-10 receptor enhances dendritic cell-based vaccine potency

Improving dendritic cell (DC) functions is highly promising for therapeutic intervention of diverse diseases, including cancer. Immunosuppressive cytokines such as interleukin (IL)-10 produced by DCs themselves (autocrine) and other regulatory immune cells (paracrine) down-regulate functional profiles of DCs through specific cell surface receptors such as IL-10R. Here, we tried to improve DC functions using small interfering RNA (siRNA) technology to block an IL-10R-mediated immunosuppressive axis. DCs modified with siRNA targeting against IL-10R or IL-10 (DC/siIL-10R or DC/siIL-10) led to up-regulation of major histocompatibility complex (MHC) class II, CD40 co-stimulatory molecule, and IL-12 proinflammatory cytokine after lipopolysacharide (LPS) stimulation compared to DC/siGFP. Notably, the LPS-induced functional profiles of DC/siIL-10R were strongly resistant to the addition of recombinant IL-10, which mimicked paracrine IL-10. In contrast, those of DC/siIL-10 were reversed by adding exogenous IL-10. Consistently, DC/siIL-10R generated more human papilloma virus (HPV) E7-specific CD8(+) T cells and stronger anti-tumour effects against E7-expressing TC-1 tumour cells in vaccinated mice than DC/siGFP, as well as DC/siIL-10. Taken together, these results provide the groundwork for future clinical translation of siRNA-mediated strategy targeting IL-10R to enhance DC-based vaccine potency.

Enhancement of dendritic cells as vaccines for cancer

Dendritic cells are the most potent antigen-presenting cells known; owing to their ability to stimulate antigen-specific cytolytic and memory T-cell responses, their use as cancer vaccines is rapidly increasing. While clinical trials provide evidence that dendritic cells vaccines are safe and elicit immunological responses in most patients, few complete tumor remissions have been reported and further technological advances are required. An effective dendritic cell vaccine must possess and maintain several characteristics: it must migrate to lymph nodes, have a mature, Th1-polarizing phenotype expressed stably after infusion and present antigen for sufficient time to produce a T-cell response capable of eliminating a tumor. While dendritic cells are readily matured ex vivo, their phenotype and fate after infusion are rarely evaluable; therefore, strategies to ensure that dendritic cells access lymphoid tissues and retain an immunostimulatory phenotype are required. In order to best exploit dendritic cells as vaccines, they may require genetic modification and combination with other strategies including adoptive T-cell transfer, inhibition of regulatory T cells or modulation of inflammatory pathways.

Molecular mechanism of MART-1+/A*0201+ human melanoma resistance to specific CTL-killing despite functional tumor-CTL interaction

Durable responses in metastatic melanoma patients remain generally difficult to achieve. Adoptive cell therapy (ACT) with ex vivo engineered lymphocytes expressing high affinity T-cell receptors (TCRα/β) for the melanoma antigen MART-1₂₇₋₃₅/HLA-A*0201 [recognized by F5 cytotoxic T lymphocytes (F5 CTL)] has been found to benefit certain patients. However, many other patients are inherently unresponsive and/or relapse for unknown reasons. To analyze the basis for the acquired resistance and strategies to reverse it, we established F5 CTL-resistant (R) human melanoma clones from relatively sensitive parental lines under selective F5 CTL pressure. Surface MART-1₂₇₋₃₅/HLA-A*0201 in these clones was unaltered and F5 CTLs recognized and interacted with them similar to the parental lines. Nevertheless, the R clones were resistant to F5 CTL killing, exhibited hyperactivation of the NF-κB survival pathway, and overexpression of the antiapoptotic genes B cell lymphoma protein 2 (Bcl-2), Bcl-2 related gene (long alternatively spliced variant of Bcl-x gene; Bcl-(xL)), and myeloid cell differentiation 1 (Mcl-1). Sensitivity to F5 CTL-killing could be increased by pharmacological inhibition of the NF-κB pathway, Bcl-2 family members, or the proteasome, the latter of which reduced NF-κB activity and diminished antiapoptotic gene expression. Specific gene-silencing (by siRNA) confirmed the protective role of antiapoptotic factors by reversing R clone resistance. Together, our findings suggest that long-term immunotherapy may impose a selection for the development of resistant cells that are unresponsive to highly avid and specific melanoma-reactive CTLs, despite maintaining expression of functional peptide:MHC complexes, due to activation of antiapoptotic signaling pathways. Though unresponsive to CTL, our results argue that resistant cells can be resensitized to immunotherapy with coadministration of targeted inhibitors to antiapoptotic survival pathways.

Knockdown of the interleukin-6 receptor alpha chain of dendritic cell vaccines enhances the therapeutic potential against IL-6 producing tumors

Tumor microenvironment has emerged as one of the major obstacles against the clinical efficacy of dendritic cell (DC) vaccines. Tumor-derived IL-6 may inhibit the differentiation of hematopoietic progenitor cells into DCs and suppress DC maturation, rendering DCs tolerogenic. We hypothesized that silencing the IL-6 receptor alpha chain (IL-6Rα) would restore the functional competence of DC vaccines in mice with an IL-6-producing TC-1 tumor, and eventually give rise to protective immunity. We found that the IL-6Rα knockdown-DC vaccine significantly enhanced the frequency of tumor-specific CD8(+) CTLs-producing effector molecules such as IFN-γ, TNF-α, FasL, perforin, and granzyme B, and generated more CD8(+) memory T cells, leading to the substantially prolonged survival of TC-1 tumor-bearing mice.

Enhancement of DC vaccine potency by activating the PI3K/AKT pathway with a small interfering RNA targeting PTEN

Dendritic cell (DC)-based cancer vaccines have become important as an immunotherapeutics in generating anti-tumor immune responses. Due to a short lifespan of DCs, however, clinical application of current DC vaccines has been limited. Recently, activation of AKT/protein kinase B (PKB), a major effector of phosphatidylinositol 3-kinase (PI3K), has been reported as a critical factor in both activation and survival of DCs. We here improved the potency of a DC vaccine with a small interfering RNA (siRNA) targeting phosphatase and tensin homologue (PTEN), which is known to be a central negative regulator of the PI3K/AKT signal transduction cascade. Down-regulation of PTEN in DCs resulted in AKT dependent maturation, which in turn caused a significant up-regulation of surface expression in co-stimulatory molecules and the chemokine receptor, CCR7, leading to an increase of in vitro T cell activation activity and in vivo migration to a draining lymph node, respectively. Moreover, these PTEN siRNA-transfected DCs (DC/siPTEN) acquired an increased survival from the apoptotic death caused by GM-CSF deprivation or antigen-specific CD8(+) T cell killing. Most importantly, DC/siPTEN generated more tumor antigen-specific CD8(+) T cells and stronger anti-tumor effects in vaccinated mice than did control DCs (DC/siGFP). Thus, our data indicate that manipulation of the PI3K/AKT pathway via siRNA system could improve the efficacy of a DC-based tumor vaccine.

Dendritic cell apoptosis: regulation of tolerance versus immunity

Dendritic cell (DC) apoptosis is an important event that regulates the balance between tolerance and immunity through multiple pathways, and defects in DC apoptosis can trigger autoimmunity. DC apoptosis is also associated with immunosuppression and has been observed under several pathologies and infections. Recent studies indicate that apoptotic DCs can also play an active role in induction of tolerance. This review discusses the regulatory pathways of DC apoptosis, stimuli inducing DC apoptosis, and the implications of DC apoptosis in the induction of immunosuppression and/or tolerance.

Immunotherapy for cervical cancer: Research status and clinical potential

The high-risk types of human papillomavirus (HPV) have been found to be associated with most cervical cancers and play an essential role in the pathogenesis of the disease. Despite recent advances in preventive HPV vaccine development, such preventive vaccines are unlikely to reduce the prevalence of HPV infections within the next few years, due to their cost and limited availability in developing countries. Furthermore, preventive HPV vaccines may not be capable of treating established HPV infections and HPV-associated lesions, which account for high morbidity and mortality worldwide. Thus, it is important to develop therapeutic HPV vaccines for the control of existing HPV infection and associated malignancies. Therapeutic vaccines are quite different from preventive vaccines in that they require the generation of cell-mediated immunity, particularly T cell-mediated immunity, instead of the generation of neutralizing antibodies. The HPV-encoded early proteins, the E6 and E7 oncoproteins, form ideal targets for therapeutic HPV vaccines, since they are consistently expressed in HPV-associated cervical cancer and its precursor lesions and thus play crucial roles in the generation and maintenance of HPV-associated disease. Our review covers the various therapeutic HPV vaccines for cervical cancer, including live vector-based, peptide or protein-based, nucleic acid-based, and cell-based vaccines targeting the HPV E6 and/or E7 antigens. Furthermore, we review the studies using therapeutic HPV vaccines in combination with other therapeutic modalities and review the latest clinical trials on therapeutic HPV vaccines.

Pem renders tumor cells resistant to apoptotic cell death induced by a CD8+ T cell-mediated immune response or anticancer drug treatment

Pem, a member of homeobox genes, is an oncofetal gene which is preferentially expressed in reproductive tissues and in multiple tumor cell lines. However, the function of Pem in tumor cell lines has not been elucidated. Herein we report that the ectopic expression of Pem in TC-1, a human papillomavirus type 16 (HPV-16) E7-expressing surrogate cervical tumor cell line, demonstrated a significant increase in extracellular signal-regulated kinase (ERK) activity and multiple resistance to various apoptotic pressures from an E7-specific CD8(+) T cell-mediated immune response and anticancer drug treatment. The observed resistance to apoptotic death of the Pem-over-expressing TC-1 tumor cells (TC-1/Pem) was associated with the down-regulation of a pro-apoptotic molecule, such as BIM, and up-regulation of an anti-apoptotic molecule, such as Bcl-2 protein, which mediated ERK activation. We also observed that the intratumoral injection of an ERK inhibitor enhanced the therapeutic efficacy of E7-specific CD8(+) T cell adoptive transfer or anticancer drug treatment against the resistant TC-1/Pem tumor. This is the first evidence demonstrating an association between Pem and a signaling pathway, namely the ERK-mediated survival signal transduction pathway. Thus, our data indicate that activation of the ERK pathway represents a new mechanism of Pem-mediated multiple resistances and the present research will contribute to the development of a novel strategy in cancer therapy against Pem-over-expressing tumor cells.

Dynamic regulation of functionally distinct virus-specific T cells

The functional capacities of CD8(+) T cells important for virus clearance are influenced by interactions with antigen presenting cells (APCs) and CD4(+) T cells during initial selection, subsequent expansion, and development of memory. Recently, investigators have shown that polyfunctional T cells correlate best with long-term protection, however, it is still unknown how to stimulate T cells to achieve these responses. To study this, we examined the phenotypes and functions of CD8(+) T cells specific for two different virus antigens stimulated ex vivo using either autologous monocyte-derived dendritic cells (moDCs) or HLA-A2-Ig-based artificial APCs (aAPCs). Although similar numbers of influenza virus and measles virus tetramer-positive cells were generated by stimulation with peptide-loaded moDCs and aAPCs, T cell function, assessed by expression of IL-2, IFN-gamma, TNF-alpha, MIP1beta, and CD107a, showed that aAPC-generated CD8(+) T cells were multifunctional, whereas moDC-generated cells were mostly monofunctional. aAPC-generated cells also produced more of each cytokine per cell than CD8(+) T cells generated with moDCs. These phenotypes were not fixed, as changing the culture conditions of expanding T cells from aAPCs to moDCs, and moDCs to aAPCs, reversed the phenotypes. We conclude that CD8(+) T cells are heterogeneous in their functionality and that this is dependent, in a dynamic way, on the stimulating APC. These studies will lead to understanding the factors that influence induction of optimal CD8(+) T cell function.

Perspectives for preventive and therapeutic HPV vaccines

Human Papillomavirus (HPV) has been associated with several human cancers, including cervical cancer, vulvar cancer, vaginal and anal cancer, and a subset of head and neck cancers. Thus effective vaccination against HPV provides an opportunity to reduce the morbidity and mortality associated with HPV. The Food and Drug Administration of the United States has approved two preventive vaccines to limit the spread of HPV. However, these are unlikely to impact upon HPV prevalence and cervical cancer rates for many years. Furthermore, preventive vaccines do not exert therapeutic effects on pre-existing HPV infections and HPV-associated lesions. In order to further impact upon the burden of HPV infections worldwide, therapeutic vaccines are being developed. These vaccines aim to generate a cell-mediated immune response to infected cells. This review discusses current preventive and therapeutic HPV vaccines and their future directions.

Anti-perforin neutralizing antibody reduces myocardial injury in viral myocarditis

AIM

To investigate the role of anti-perforin neutralizing antibody in viral myocarditis.

METHODS

We divided 45 Balb/c mice randomly into 3 groups, a normal control group, a control group inoculated with coxsackie virus B3, and a group inoculated with anti-perforin neutralizing antibody. The second group was inoculated with 0.15 milliliters coxsackie virus B3, and the third group additionally with 0.1 milligrams/kilogram anti-perforin neutralizing antibody at time points of 6 hours and 3 days after infection. Histopathology was performed using haematoxylin and eosin, with apoptosis examined by the terminal transferase-mediated 2'-deoxyuridine 5'-triphosphate-biotin nick, end-labeling method, or Tunel. The expression of caspase-3 in myocardium was investigated by immunohistochemistry and reverse-transcription polymerase chain reaction.

RESULTS

The pathologic score, myocardial viral titers, average percentages of apoptotic cardiomyocytes, expression of active caspase-3 protein and messenger ribonucleic acid in the myocardium of the mice receiving anti-PFP neutralizing antibody therapy were all significantly reduced when compared to values from the group inoculated with coxsackie virus B3. The rates of expression of Caspase-3 and myocardial apoptosis were positively correlated with the scores for myocardial pathology.

CONCLUSION

Our results suggest that anti- perforin neutralizing antibody can reduce the myocardial damage by blocking the perforin/granzyme pathway, and downregulating the expression of messenger ribonucleic acid and protein of Caspase-3. These approaches may offer promising novel therapeutic strategies for the clinical treatment of viral myocarditis.

A comparative study of transfection methods for RNA interference in bone marrow-derived murine dendritic cells

Selective gene silencing using RNA interference (RNAi) has been shown to be an efficient method for manipulation of cellular functions. In this study, we compare three previously established methods for transfection of murine bone marrow-derived DC (BM-DC). We tested the efficacy of electroporation with the Mouse Nucleofector kit((R)) from Amaxa Biosystems and lipid-based transfection methods using transfection reagents from Santa Cruz Biotechnology or Genlantis. To analyse the transfection efficacy we used FITC-conjugated siRNA as a positive control together with CD80 and CD86 specific siRNA. We show that electroporation using the Mouse Nucleofector kit((R)) from Amaxa Biosystems was not an efficient method to transfect BM-DC with siRNA in our hands. Transfection with Santa Cruz Biotechnology reagents resulted in up to 59% FITC-siRNA positive cells, but did not result in effective silencing of CD80 surface expression. In contrast, the most effective method was the lipid-based method using the siRNA transfection reagent GeneSilencer((R)) from Genlantis. This protocol resulted in up to 92% FITC-siRNA positive cells after 4 h which declined to 62% and 59% 24 and 48 h post-transfection, respectively. The transfected BM-DC remained CD11c positive, expressed high MHC class II and intermediate CD40 and were functional as APC. In conclusion, this protocol was effective for manipulation of murine BM-DC function through the use of specific siRNA and such methods can be important for the future study of DC-T cell interactions.