Synergistic effects of soluble PD-1 and IL-21 on antitumor immunity against H22 murine hepatocellular carcinoma

Blockade of PD-1 and CTLA-4: A potent immunotherapeutic approach for hepatocellular carcinoma

Immune checkpoints (ICPs) can promote tumor growth and prevent immunity-induced cancer cell apoptosis. Fortunately, targeting ICPs, such as programmed cell death 1 (PD-1) or cytotoxic T lymphocyte associated protein 4 (CTLA-4), has achieved great success in the past few years and has gradually become an effective treatment for cancers, including hepatocellular carcinoma (HCC). However, many patients do not respond to ICP therapy due to acquired resistance and recurrence. Therefore, clarifying the specific mechanisms of ICP in the development of HCC is very important for enhancing the efficacy of anti-PD-1 and anti-CTLA-4 therapy. In particular, antigen presentation and interferon-γ (IFN-γ) signaling were reported to be involved in the development of resistance. In this review, we have explained the role and regulatory mechanisms of ICP therapy in HCC pathology. Moreover, we have also elaborated on combinations of ICP inhibitors and other treatments to enhance the antitumor effect. Collectively, recent advances in the pharmacological targeting of ICPs provide insights for the development of a novel alternative treatment for HCC.

Recombinant Newcastle disease viruses expressing immunological checkpoint inhibitors induce a pro-inflammatory state and enhance tumor-specific immune responses in two murine models of cancer

Introduction

Tumor microenvironments are immunosuppressive due to progressive accumulation of mutations in cancer cells that can drive expression of a range of inhibitory ligands and cytokines, and recruitment of immunomodulatory cells, including myeloid-derived suppressor cells (MDSC), tumor-associated macrophages, and regulatory T cells (Tregs).

Methods

To reverse this immunosuppression, we engineered mesogenic Newcastle disease virus (NDV) to express immunological checkpoint inhibitors anti-cytotoxic T lymphocyte antigen-4 and soluble programmed death protein-1.

Results

Intratumoral administration of recombinant NDV (rNDV) to mice bearing intradermal B16-F10 melanomas or subcutaneous CT26LacZ colon carcinomas led to significant changes in the tumor-infiltrating lymphocyte profiles. Vectorizing immunological checkpoint inhibitors in NDV increased activation of intratumoral natural killer cells and cytotoxic T cells and decreased Tregs and MDSCs, suggesting induction of a pro-inflammatory state with greater infiltration of activated CD8+ T cells. These notable changes translated to higher ratios of activated effector/suppressor tumor-infiltrating lymphocytes in both cancer models, which is a promising prognostic marker. Whereas all rNDV-treated groups showed evidence of tumor regression and increased survival in the CT26LacZ and B16-F10, only treatment with NDV expressing immunological checkpoint blockades led to complete responses compared to tumors treated with NDV only.

Discussion

These data demonstrated that NDV expressing immunological checkpoint inhibitors could reverse the immunosuppressive state of tumor microenvironments and enhance tumor-specific T cell responses.

Biological effects of IL-21 on immune cells and its potential for cancer treatment

Interleukin-21 (IL-21), a member of the IL-2 cytokine family, is one of the most important effector and messenger molecules in the immune system. Produced by various immune cells, IL-21 has pleiotropic effects on innate and adaptive immune responses via regulation of natural killer, T, and B cells. An anti-tumor role of IL-21 has also been reported in the literature, as it may support cell proliferation or on the contrary induce growth arrest or apoptosis of the tumor cell. Anti-tumor effect of IL-21 enhances when combined with other agents that target tumor cells, immune regulatory circuits, or other immune-enhancing molecules. Therefore, understanding the biology of IL-21 in the tumor microenvironment (TME) and reducing its systemic toxic and side effects is crucial to ensure the maximum benefits of anti-tumor treatment strategies. In this review, we provide a comprehensive overview on the biological functions, roles in tumors, and the recent advances in preclinical and clinical research of IL-21 in tumor immunotherapy.

Biological Characteristics and Clinical Significance of Soluble PD-1/PD-L1 and Exosomal PD-L1 in Cancer

The immune checkpoint pathway consisting of the cell membrane-bound molecule programmed death protein 1 (PD-1) and its ligand PD-L1 has been found to mediate negative regulatory signals that effectively inhibit T-cell proliferation and function and impair antitumor immune responses. Considerable evidence suggests that the PD-1/PD-L1 pathway is responsible for tumor immune tolerance and immune escape. Blockage of this pathway has been found to reverse T lymphocyte depletion and restore antitumor immunity. Antagonists targeting this pathway have shown significant clinical activity in specific cancer types. Although originally identified as membrane-type molecules, several other forms of PD-1/PD-L1 have been detected in the blood of cancer patients, including soluble PD-1/PD-L1 (sPD-1/sPD-L1) and exosomal PD-L1 (exoPD-L1), increasing the composition and functional complications of the PD-1/PD-L1 signaling pathway. For example, sPD-1 has been shown to block the PD-1/PD-L immunosuppressive pathway by binding to PD-L1 and PD-L2, whereas the role of sPD-L1 and its mechanism of action in cancer remain unclear. In addition, many studies have investigated the roles of exoPD-L1 in immunosuppression, as a biomarker for tumor progression and as a predictive biomarker for response to immunotherapy. This review describes the molecular mechanisms underlying the generation of sPD-1/sPD-L1 and exoPD-L1, along with their biological activities and methods of detection. In addition, this review discusses the clinical importance of sPD-1/sPD-L1 and exoPD-L1 in cancer, including their predictive and prognostic roles and the effects of treatments that target these molecules.

An engineered IL-21 with half-life extension enhances anti-tumor immunity as a monotherapy or in combination with PD-1 or TIGIT blockade

Interleukin-21 (IL-21) has exhibited anti-tumor activity in preclinical and clinical studies; however, its modest efficacy and short half-time has limited its therapeutic utility as a monotherapy. Therefore, we engineered a fusion protein (IL-21-αHSA) in which a nanobody targeting human serum albumin (HSA) was fused to the C-terminus of rhIL-21. The αHSA nanobody displayed broad species cross-reactivity and bound to a HSA epitope that does not overlap with the FcRn binding site, thus providing a strategic design for half-life extension. The IL-21-αHSA fusion protein showed increased stability compared to rhIL-21, while retaining its bioactivity in a liquid solution for at least 6 months. Moreover, IL-21-αHSA showed a dramatically extended half-life and prolonged exposure in cynomolgus monkeys, with the t_1/2 and AUC nearly 10 and 50 times greater than that of rhIL-21, respectively. Furthermore, IL-21-αHSA displayed enhanced anti-tumor efficacy in two syngeneic mouse models. Notably, IL-21-αHSA increased the anti-tumor effect of programmed cell death protein 1 (PD-1) and T cell immunoglobulin and ITIM domain (TIGIT) blockades when used in combination, with a protection against tumor rechallenge, suggesting the formation of long-term anti-tumor memory response. KEGG analysis identified significantly enriched pathways associated with anti-tumor immune response, with increased expression of genes associated with CD8⁺ T and NK cell cytotoxicity. Overall, these data support further clinical evaluation of IL-21-αHSA as a monotherapy or in combination with immune checkpoint blockades.

Soluble B7-CD28 Family Inhibitory Immune Checkpoint Proteins and Anti-Cancer Immunotherapy

Co-inhibitory B7-CD28 family member proteins negatively regulate T cell responses and are extensively involved in tumor immune evasion. Blockade of classical CTLA-4 (cytotoxic T lymphocyte-associated antigen-4) and PD-1 (programmed cell death protein-1) checkpoint pathways have become the cornerstone of anti-cancer immunotherapy. New inhibitory checkpoint proteins such as B7-H3, B7-H4, and BTLA (B and T lymphocyte attenuator) are being discovered and investigated for their potential in anti-cancer immunotherapy. In addition, soluble forms of these molecules also exist in sera of healthy individuals and elevated levels are found in chronic infections, autoimmune diseases, and cancers. Soluble forms are generated by proteolytic shedding or alternative splicing. Elevated circulating levels of these inhibitory soluble checkpoint molecules in cancer have been correlated with advance stage, metastatic status, and prognosis which underscore their broader involvement in immune regulation. In addition to their potential as biomarker, understanding their mechanism of production, biological activity, and pathological interactions may also pave the way for their clinical use as a therapeutic target. Here we review these aspects of soluble checkpoint molecules and elucidate on their potential for anti-cancer immunotherapy.

Soluble PD-1: Predictive, Prognostic, and Therapeutic Value for Cancer Immunotherapy

Programmed death protein 1 (PD-1) interaction with PD-L1 deliver immunosuppressive environment for tumor growth, and its blockade with directed monoclonal antibodies (anti-PD-1/anti-PD-L1) has shown remarkable clinical outcome. Lately, their soluble counterparts, sPD-1 and sPD-L1, have been detected in plasma, and elevated levels have been associated with advanced disease, clinical stages, and worst prognosis for cancer patients. Elevated plasma levels of sPD-L1 have been correlated with worst prognosis in several studies and has displayed a persistent outlook. On the other hand, sPD-1 levels have been inconsistent in their predictive and prognostic ability. Pretherapeutic higher sPD-1 plasma levels have shown to predict advanced disease state and to a lesser extent worst prognosis. Any increase in sPD-1 plasma level post therapeutically have been correlated with improved survival for various cancers. In vitro and in vivo studies have shown sPD-1 ability to bind PD-L1 and PD-L2 and block PD-1/PD-L1 interaction. Local delivery of sPD-1 in cancer tumor microenvironment through local gene therapy have demonstrated an increase in tumor specific CD8+ T cell immunity and tumor growth reduction. It had also exhibited enhancement of T cell immunity induced by vaccination and other gene therapeutic agents. Furthermore, it may also lessen the inhibitory effect of circulating sPD-L1 and enhance the effects of mAb-based immunotherapy. In this review, we highlight various aspects of sPD-1 role in cancer prediction, prognosis, and anti-cancer immunity, as well as, its therapeutic value for local gene therapy or systemic immunotherapy in blocking the PD-1 and PD-L1 checkpoint interactions.

Advances in engineering local drug delivery systems for cancer immunotherapy

Cancer immunotherapy aims to leverage the immune system to suppress the growth of tumors and to inhibit metastasis. The recent promising clinical outcomes associated with cancer immunotherapy have prompted research and development efforts towards enhancing the efficacy of immune checkpoint blockade, cancer vaccines, cytokine therapy, and adoptive T cell therapy. Advancements in biomaterials, nanomedicine, and micro-/nano-technology have facilitated the development of enhanced local delivery systems for cancer immunotherapy, which can enhance treatment efficacy while minimizing toxicity. Furthermore, locally administered cancer therapies that combine immunotherapy with chemotherapy, radiotherapy, or phototherapy have the potential to achieve synergistic antitumor effects. Herein, the latest studies on local delivery systems for cancer immunotherapy are surveyed, with an emphasis on the therapeutic benefits associated with the design of biomaterials and nanomedicines. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Profiles of serum soluble programmed death-1 and programmed death-ligand 1 levels in chronic hepatitis B virus-infected patients with different disease phases and after anti-viral treatment

BACKGROUND

Soluble programmed death-1 (sPD-1) and soluble programmed death-ligand 1 (sPD-L1) play a role in immune regulation of chronic hepatitis B virus (HBV) infection.

AIM

To investigate the profiles of serum sPD-1 and sPD-L1 in chronic HBV-infected patients with different disease phases and after anti-viral treatment.

METHODS

A total of 99 chronic HBV-infected patients were enrolled and divided into HBeAg-positive chronic HBV infection (EPI) group, HBeAg-positive chronic hepatitis B (EPH) group, HBeAg-negative chronic hepatitis B (ENH) group and HBeAg-negative chronic HBV infection (ENI) group. Eleven healthy subjects were included as healthy controls (HCs). Thirty-two EPH patients received anti-viral treatment with nucleos(t)ide analogues and were followed up to 5 years. Serum sPD-1 and sPD-L1 levels were detected by Multiplex Immunoassays.

RESULTS

Serum sPD-1 and sPD-L1 levels of chronic HBV infected patients were significantly higher than that of HCs (P < 0.01). Patients in EPH, ENH and EPI groups had higher serum sPD-1 and sPD-L1 levels than that in HCs (P < 0.01). After anti-viral treatment, serum sPD-1 and sPD-L1 levels declined rapidly. EPH patients with HBeAg clearance after 2 years of anti-viral treatment showed lower baseline HBeAg and sPD-1 levels compared to those without HBeAg clearance.

CONCLUSIONS

Serum sPD-1 and sPD-L1 levels varied among chronic HBV infected patients with different disease phases. Lower baseline sPD-1 levels were associated with HBeAg clearance after 2 years of anti-viral treatment in EPH patients.

GITR Agonism Triggers Antitumor Immune Responses through IL21-Expressing Follicular Helper T Cells

Although treatment with the glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR) agonistic antibody (DTA-1) has shown antitumor activity in various tumor models, the underlying mechanism is not fully understood. Here, we demonstrate that interleukin (IL)-21-producing follicular helper T (Tfh) cells play a crucial role in DTA-1-induced tumor inhibition. The administration of DTA-1 increased IL21 expression by Tfh cells in an antigen-specific manner, and this activation led to enhanced antitumor cytotoxic T lymphocyte (CTL) activity. Mice treated with an antibody that neutralizes the IL21 receptor exhibited decreased antitumor activity when treated with DTA-1. Tumor growth inhibition by DTA-1 was abrogated in Bcl6 ^fl/fl Cd4 ^Cre mice, which are genetically deficient in Tfh cells. IL4 was required for optimal induction of IL21-expressing Tfh cells by GITR costimulation, and c-Maf mediated this pathway. Thus, our findings identify GITR costimulation as an inducer of IL21-expressing Tfh cells and provide a mechanism for the antitumor activity of GITR agonism.

Producing Soluble Human Programmed Cell Death Protein-1: A Natural Supporter for CD4+T Cell Cytotoxicity and Tumor Cells Apoptosis

BACKGROUND

Programmed cell death protein-1 (PD-1)/PD-L1 pathway is one of the immune checkpoint pathways involved in the regulation of the immune responses and the suppression of anti-tumor defense. PD-1/PD-L1 blocking antibodies improve immune responses such as cytotoxic activity of CD8+/CD4+T cells and increase mortality of tumor cells as well; however, their use is accompanied by adverse side effects.

OBJECTIVES

We aimed to produce a native blocker of human PD-1/PD-L1, for developing T cells cytotoxicity and tumor cells apoptosis.

MATERIALS AND METHODS

We designed and cloned soluble human PD-1-GFP-pcDNA3.1/hygro construct in Escherichia coli strain TOP10 cells and then transfected this construct into the HEK cells. The concentration of the secreted shPD-1 in the supernatant was measured and the supernatant was used for blocking PD-L1 on the MDA-MB-231 cells. The cytotoxicity of CD8+/CD4+T cells and the apoptosis of MDA-MB-231 cells, under the influence of shPD-1 in the co-culture of T cells with the MDA-MB-231 cells, were evaluated using flow cytometry technique.

RESULTS

The GFP expression in the transfected cells illustrated the successful designing, transfection, and production of shPD-1. Soluble human PD-1 concentration in the supernatant of the transfected HEK cells was significantly higher than the untransfected cells. In addition, shPD-1 significantly blocked PD-L1 on the MDA- MB-231 cells, improved the cytotoxicity of CD4+T cells, and increased the apoptosis of MDA-MB-231 cells.

CONCLUSION

Overall, increased CD4+T cell cytotoxicity and tumor cells apoptosis under the influence of shPD-1, confirmed the effectiveness of shPD-1 as a natural blocker of PD-L1and as an augmenter of the anti-tumorimmune responses.

The association between interleukin-21 (rs2055979G/T) gene polymorphism and the risk of hepatocellular carcinoma and metastasis in patients with hepatitis C virus

Cancer prevalence is critically increasing worldwide; accordingly, improved prediction and therapeutic tools are necessary. Interleukin (IL)-21 is a potent antitumor cytokine, and the relationship between its gene variations and cancer risk is well established. Nevertheless, so far no study has investigated its role in hepatocellular carcinoma (HCC) progression and metastasis in hepatitis C virus (HCV)-infected people. Therefore, the present investigation was led on 267 Egyptian participants, involving 177 patients with HCV of which 90 patients had HCC (HCC group), 87 patients without HCC (non-HCC group), and 90 unrelated healthy controls. The association between rs2221903A/G and rs2055979G/T of the IL-21 gene and the risk of HCC and metastasis, as well as the clinico-pathological features, were analyzed. While rs2221903A/G polymorphism was not polymorphic in our cohort, patients carrying the genotype TT and allele T of the rs2055979G/T polymorphism had a significantly lower risk of HCC when comparing with HCC group and healthy controls. Also, participants carrying the aforementioned genotype and allele had a significantly lower risk of metastasis when comparing metastatic group with both nonmetastatic group and control group. The rs2055979G/T polymorphism was not significantly associated with clinico-pathological features of HCC. This is the first study to report a relationship between an intronic polymorphism in IL-21 gene and HCC and metastasis risk in the Egyptian people, in addition to identifying a potential new marker for the early detection and treatment of HCC.

Interleukin-21 combined with PD-1 or CTLA-4 blockade enhances antitumor immunity in mouse tumor models

Recent advances in cancer treatment with checkpoint blockade of receptors such as CTLA-4 and PD-1 have demonstrated that combinations of agents with complementary immunomodulatory effects have the potential to enhance antitumor activity as compared to single agents. We investigated the efficacy of immune-modulatory interleukin-21 (IL-21) combined with checkpoint blockade in several syngeneic mouse tumor models. After tumor establishment, mice were administered recombinant mouse IL-21 (mIL-21) alone or in combination with blocking monoclonal antibodies against mouse PD-1 or CTLA-4. In contrast to monotherapy, IL-21 enhanced antitumor activity of mCTLA-4 mAb in four models and anti-PD-1 mAb in two models, with evidence of synergy for one or both of the combination treatments in the EMT-6 and MC38 models. The enhanced efficacy was associated with increased intratumoral CD8+ T cell infiltrates, CD8+ T cell proliferation, and increased effector memory T cells, along with decreased frequency of central memory CD8+ T cells. In vivo depletion of CD8+ T cells abolished the antitumor activities observed for both combination and monotherapy treatments, further supporting a beneficial role for CD8+ T cells. In all studies, the combination therapies were well tolerated. These results support the hypothesis that the combination of recombinant human IL-21 with CTLA-4 or PD-1 monoclonal antibodies could lead to improved outcomes in cancer patients.

Evaluation of Serum Interleukin-21 and HLA-C1 Polymorphism in Pediatrician Hematopoietic Stem Cell Transplantation for Early Diagnosis of Acute Graft-Versus-Host Disease

Background:

Allogenic hematopoietic stem cell transplantation (HSCT) is a strategy used for treatment of different malignant diseases. However, success of allo-HSCT can be hampered by graft-versus-host-disease (GVHD). Natural killer (NK) cells may play an important role in activating antigen presenting cells and subsequent activation of T cells. The main purpose of this study was the evaluation of IL-21, as a blood biomarker, for early detection of acute GVHD (aGVHD) in children after HSCT and also the study of human leukocytes antigen (HLA)-C1 polymorphism, as a targeting ligand for NK cells in these patients.

Methods:

Fifty one children receiving HSCT were studied. Blood samples were collected at -8, 7, and 14 days of transplantation. The -8-day samples were analyzed for HLA-C1 polymorphism by PCR-sequence-specific primer technique and pre-transplantation IL-21 assay. To study the serum levels of IL-21, two blood samples were collected on days +7 and +14 and analyzed by ELISA technique.

Results:

The results indicated that the incidence of aGVHD in pediatric is associated with a polymorphism of HLA-C1, as alleles HLA-C01:12 (P<0.001), HLA-C01:22 (P<0.004), and HLA-C01:67 (P<0.009). On the other hand, the serum levels of IL-21 in children with aGVHD were decreased after transplantation compared to before transplantation. The serum levels of the IL-21 at 14 days after transplantation had a significant correlation with the occurrence of aGVHD (P=0.05).

Conclusion:

Based on the findings of this study, there is a significant correlation between HLA-C1 polymorphisms and the serum levels of IL-21 with the incidence of aGVHD.

Soluble PD-1 and PD-L1: predictive and prognostic significance in cancer

The membrane-bound molecules programmed death 1 (PD-1) and its ligand PD-L1 (PD-1/PD-L1) belong to the immune checkpoint pathway. PD-1 pathway downregulates effector T cells in immune response, thereby causing immune suppression. Recent studies have revealed that membrane-bound PD-1 and PD-L1 also have soluble forms. These soluble forms increase the complexity and diversity of the composition and function of the PD-1/PD-L1 signaling pathway. However, the exact roles of these molecules remain unknown. The objective of this systematic review was to elucidate the biological significance of soluble PD-1/PD-L1 in human cancers and evaluate whether they are potential diagnostic, therapeutic, or prognostic biomarkers. We expect to provide new clues for future research on soluble PD-1/PD-L1 pathway in human malignant tumors.

Prokaryotic expression of the extracellular domain of porcine programmed death 1 (PD-1) and its ligand PD-L1 and identification of the binding with peripheral blood mononuclear cells in vitro

Programmed cell death protein 1 (PD-1), a costimulatory molecule of the CD28 family, has 2 ligands, PD-L1 and PD-L2. Our previous studies showed that the expression of PD-1 and PD-L1 is up-regulated during viral infection in pigs. Extensive studies have shown that blockade of the PD-1/PD-L1 pathways by anti-PD-L1 antibody or soluble PD-1 restores exhausted T-cells in humans and mice. In the present study the extracellular domains of PD-1 and PD-L1 were used to evaluate the binding of PD-1 and PD-L1 with peripheral blood mononuclear cells (PBMCs). We amplified the cDNA encoding the extracellular domains of PD-1 and PD-L1 to construct recombinant expression plasmids and obtain soluble recombinant proteins, which were then labeled with fluorescein isothiocyanate (FITC). The His-ExPD-1 and His-ExPD-L1 recombinant proteins were expressed in the form of inclusion bodies with a relative molecular weight of 33.0 and 45.0 kDa, respectively. We then prepared polyclonal antibodies against the proteins with a multi-antiserum titer of 1:102 400. Binding of the proteins with PBMCs was evaluated by flow cytometry. The fluorescence signals of His-ExPD-1-FITC and His-ExPD-L1-FITC were greater than those for the FITC control. These results suggest that the soluble recombinant proteins may be used to prepare monoclonal antibodies to block the PD-1/PD-L1 pathway.

Adenovirus-mediated interleukin 21 gene transfer enhances antitumor immunity and reduces tumorigenicity of Hepa1-6 in mice

In the present study, adenovirus-mediated interleukin 21 (Ad5-IL-21-EGFP) gene expression was induced in Hepa1–6 cells to investigate whether IL-21 was capable of enhancing antitumor immunity and reducing tumorigenicity of Hepa1–6 in a mouse model. Mice were inoculated intradermally into the right flank with Hepa1–6 cells or Hepa1–6 cells infected with Ad5 or Ad5-IL-21. Four weeks later, the mice were sacrificed humanely, and the tumor volume, tumor weight and mouse spleen index were measured. The levels of IL-21, IL-4 and interferon (IFN)-γ levels in mouse serum and tumor tissues were detected by enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry. Cell counting kit-8 (CCK-8) assay was used to detect the killing ability of spleen T cells and natural killer (NK) cells, and the proliferation ability of T cells. The expression of IL-21 was confirmed by reverse transcription-polymerase chain reaction, western blot analysis and ELISA assay in Ad5-IL-21-EGFP-infected Hepa1–6 cells. The overexpression of IL-21 significantly reduced the tumorigenicity of Hepa1–6 cells. The tumor volumes and tumor weights in Ad5-IL-21-Hepa1–6 mice were much smaller than those in the Ad5-Hepa1–6 group and Hepa1–6 wild-type group. The immunohistochemistry and ELISA assay demonstrated that IL-21 and IFN-γ levels were much higher while the IL-4 level was much lower in the Ad5-IL-21-Hepa1–6 group than in the other two groups. CCK-8 assay revealed that the killing ability of NK cells and T cells, and the proliferation ability of T cells in Ad5-IL-21-Hepa1–6 mice were higher than in the other two groups; the spleen index of Ad5-IL-21-Hepa1–6 mice was also higher than in the other groups. The data had a significant difference (P<0.01). In conclusion, IL-21 reduces tumorigenicity of Hepa1–6 by a mechanism involving enhanced activation of cell-mediated immunity in tumor-bearing mice.

Programmed cell death 1 correlates with the occurrence and development of MG63 osteosarcoma

The aim of the present study was to investigate the effect of programmed cell death 1 (PD-1) on osteosarcoma (OD) stem cells and T cells, and to determine their correlation. OS stem cells were sorted and identified from OS MG63 cells. Flow cytometry was used to detect the PD-1 expression of the OS tumor stem cell membrane surface. The expression of PD-1 mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR). MTT was used to detect the effect of PD-1 signals on T-cell proliferation. The results indicated that the cancer cells (cultured in DMEM medium containing 10% fetal bovine serum) exhibited clear proliferation within 1 week of cell culture, which showed their strong proliferation and aggressive ability. The formation of tumor cell spheres was dependent on the support of serum nutrition. The proliferation of MG63 cells in the serum culture medium was significantly higher than the number of OS cell spheres in serum-free suspension culture (P<0.05). Pluripotent stem cells in cancer cell spheres exhibited significantly higher cluster of differentiation 133 expression compared with the MG63 cells. The PD-1 expression levels of the cancer cell spheres was significantly increased compared with the MG63 cells, which is consistent with the results of the RT-PCR. In conclusion, the MG63 cell line possesses the features of OS stem cells. The MG63 cell line can express the certain cancer-associated cell markers. The expression of PD-1 in spheres was also increased significantly compared to the MG63 cells, which can reduce the immune function of patients and may be closely associated with the occurrence and development of tumors.

Association between interleukin-21 gene polymorphisms (rs12508721) and HBV-related hepatocellular carcinoma

Interleukin-21 (IL-21), as a multifunctional cytokine, plays an important role in many diseases, such as cancer, inflammatory and autoimmune diseases. We aimed to investigate the relationship between polymorphisms of IL-21 gene and susceptibility of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) in a Chinese population. Studied subjects were divided into three groups: 100 patients with HBV-related HCC, 115 patients with chronic HBV infection and 127 healthy controls. Genomic DNA was isolated from peripheral blood, and the polymerase chain reaction-ligase detection reaction (PCR-LDR) method was used to genotype the SNPs (rs2221903, rs907715 and rs12508721) within IL-21 gene. Our results showed that IL-21 polymorphisms were associated with the risk of HCC and chronic HBV infection when compared with healthy controls. The rs2221903A/G AG genotype was associated with a higher risk of chronic HBV infection when compared with healthy controls [AG versus AA + GG, P = 0.036, OR = 1.898, 95%CI = 1.038-3.471]. The rs12508721C/T TT genotype was related with a lower risk of chronic HBV infection and HBV-related HCC than in healthy controls [TT versus CT + CC, P = 0.026, OR = 0.451, 95%CI = 0.221-0.920; P = 0.049, OR = 0.482, 95%CI = 0.231-1.005]. No significant difference in the genotype and allele distrubutions of rs907715G/A SNP was observed in the HBV-related HCC group, chronic HBV-infected group and the healthy control group when compared to each other. Our findings suggest that the rs12508721T/C and rs2221903A/G polymorphisms of IL-21 gene are associated with the susceptibility of HBV-related HCC and chronic HBV infection. The genetic variant may in fact cause protection against the HBV-related HCC. However, the function in these SNPs of IL-21 gene needs to clarify the mechanisms involved in the pathogenesis of HBV-related HCC further.

[Levels of programmed death-1 and programmed death ligand-1 in the peripheral blood of patients with oral squamous cell carcinoma and its clinical implications]

OBJECTIVE

To detect the expression levels of programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1) in the peripheral blood of patients with oral squamous cell carcinoma (OSCC) and to discuss their biological and clinical significance.

METHODS

PD-1/PD-L1 expression on the surface of T-lymphocytes and the counts of T-lymphocyte subpopulations of peripheral blood in 82 patients with OSCC (OSCC group) and 25 healthy controls (control group) were examined via flow cytometry. The expression levels of soluble PD-1 (sPD-1) and soluble PD-L1 (sPD-L1) in the serum were observed through enzyme-link immunology method. The data were tested and analyzed with SPSS 17.0 software.

RESULTS

The percentage of CD8+ T cells in the OSCC group was significantly higher than that in the control group (P<0.05), whereas the percentages of CD3+ and CD4+ T cells as well as CD4+/CD8+ ratio were significantly lower than those in the control group (P<0.05). The positive rates of PD-1 and PD-L1 in CD3+ and CD4+ T cells in OSCC peripheral blood were remarkably higher than those in the control group (P<0.01). Difference was not observed between the expression levels of sPD-1 in the serum of OSCC group and those in the control group (P>0.05), but the average of sPD-L1 was remarkably higher than that in the control group (P<0.05). sPD-L1 expression was related to clinical stage, tumor cell differentiation, and lymph node status (P<0.05) but not related to sex, age, tumor location, and tumor size.

CONCLUSION

T-lymphocyte subpopulations in the peripheral blood of patients with OSCC developed immunosuppression with different degrees. PD-1 and PD-L1 expression levels on the surface of CD3+ and CD4+ T cells significantly increased. Abnormal increase in sPD-L1 expression may be associated with OSCC development.

[Levels of programmed death-1 and programmed death ligand-1 in the peripheral blood of patients with oral squamous cell carcinoma and its clinical implications]

OBJECTIVE

To detect the expression levels of programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1) in the peripheral blood of patients with oral squamous cell carcinoma (OSCC) and to discuss their biological and clinical significance.

METHODS

PD-1/PD-L1 expression on the surface of T-lymphocytes and the counts of T-lymphocyte subpopulations of peripheral blood in 82 patients with OSCC (OSCC group) and 25 healthy controls (control group) were examined via flow cytometry. The expression levels of soluble PD-1 (sPD-1) and soluble PD-L1 (sPD-L1) in the serum were observed through enzyme-link immunology method. The data were tested and analyzed with SPSS 17.0 software.

RESULTS

The percentage of CD8+ T cells in the OSCC group was significantly higher than that in the control group (P<0.05), whereas the percentages of CD3+ and CD4+ T cells as well as CD4+/CD8+ ratio were significantly lower than those in the control group (P<0.05). The positive rates of PD-1 and PD-L1 in CD3+ and CD4+ T cells in OSCC peripheral blood were remarkably higher than those in the control group (P<0.01). Difference was not observed between the expression levels of sPD-1 in the serum of OSCC group and those in the control group (P>0.05), but the average of sPD-L1 was remarkably higher than that in the control group (P<0.05). sPD-L1 expression was related to clinical stage, tumor cell differentiation, and lymph node status (P<0.05) but not related to sex, age, tumor location, and tumor size.

CONCLUSION

T-lymphocyte subpopulations in the peripheral blood of patients with OSCC developed immunosuppression with different degrees. PD-1 and PD-L1 expression levels on the surface of CD3+ and CD4+ T cells significantly increased. Abnormal increase in sPD-L1 expression may be associated with OSCC development.

IL-21: a pleiotropic cytokine with potential applications in oncology

Interleukin- (IL-) 21 is a pleiotropic cytokine that regulates the activity of both innate and specific immunity. Indeed, it costimulates T and natural killer (NK) cell proliferation and function and regulates B cell survival and differentiation and the function of dendritic cells. In addition, IL-21 exerts divergent effects on different lymphoid cell leukemia and lymphomas, as it may support cell proliferation or on the contrary induce growth arrest or apoptosis of the neoplastic lymphoid cells. Several preclinical studies showed that IL-21 has antitumor activity in different tumor models, through mechanism involving the activation of NK and T or B cell responses. Moreover, IL-21's antitumor activity can be potentiated by its combination with other immune-enhancing molecules, monoclonal antibodies recognizing tumor antigens, chemotherapy, or molecular targeted agents. Clinical phase I-II studies of IL-21 in cancer patients showed immune stimulatory properties, acceptable toxicity profile, and antitumor effects in a fraction of patients. In view of its tolerability, IL-21 is also suitable for combinational therapeutic regimens with other agents. This review will summarize the biological functions of IL-21, and address its role in lymphoid malignancies and preclinical and clinical studies of cancer immunotherapy.

The PD-1/PD-Ls pathway and autoimmune diseases

The programmed death (PD)-1/PD-1 ligands (PD-Ls) pathway, is a new member of the B7/CD28 family, and consists of the PD-1 receptor and its ligands PD-L1 (B7-H1, CD274) and PD-L2 (B7-DC, CD273). Recently, it is reported that PD-1, PD-L1 and PD-L2 also have soluble forms aside from their membrane bound forms. The soluble forms increase the diversity and complexity of PD-1/PD-Ls pathway in both composition and function. The PD-1/PD-Ls pathway is broadly expressed and exerts a wider range of immunoregulatory roles in T-cell activation and tolerance compared with other B7/CD28 family members. Studies show that the PD-1/PD-Ls pathway regulates the induction and maintenance of peripheral tolerance and protects tissues from autoimmune attack in physiological conditions. In addition, it is also involved in various diseases mediated by T cells, such as autoimmunity, tumor immunity, chronic viral infections, and transplantation immunity. In this review, we will summarize the relevance of the soluble forms and the latest researches on the role of PD-1/PD-Ls pathway in autoimmune diseases.

Expression of costimulatory molecules B7-H1, B7-H4 and Foxp3+ Tregs in gastric cancer and its clinical significance

OBJECTIVE

Immune escape plays an important role in tumor progression. In the present study, the expression of B7-H1, B7-H4 and Foxp3 involved in immune escape in gastric carcinoma was investigated and the corresponding clinical significance was evaluated.

METHODS

Immunohistochemistry was used to detect the expression of B7-H1, B7-H4 and Foxp3 in 100 gastric cancer specimens, and 30 paracarcinoma tissues were used as the control.

RESULTS

Both B7-H1 and B7-H4 showed high expression levels in gastric cancer tissues (65.0 and 71.0 %, respectively), and the expressions of B7-H1 and B7-H4 were positively correlated with the depth of tumor invasion, lymph node metastasis and American Joint Committee on Cancer (AJCC) stage (P < 0.05). The number of Foxp3(+) Tregs was much higher in gastric cancer tissues than control tissues, which was positively correlated with lymph node metastasis (P < 0.05). Similarly, a positive correlation between B7-H1 or B7-H4 expression and the number of Foxp3(+) Tregs was observed. The median overall survival rate of patients with high expression of B7-H1, B7-H4 and Foxp3 was significantly poorer than that of patients with low expression of these proteins (P < 0.05). Cox regression multivariate analysis confirmed that lymph node metastasis, AJCC stage, and B7-H1 and Foxp3 overexpression were independent prognostic factors.

CONCLUSION

B7-H1, B7-H4 and Foxp3 were overexpressed in gastric cancer tissues. B7-H1 and Foxp3 are negative prognostic factors for patients with gastric cancer.

Activation of cellular immunity and marked inhibition of liver cancer in a mouse model following gene therapy and tumor expression of GM-SCF, IL-21, and Rae-1

Background

Cancer is both a systemic and a genetic disease. The pathogenesis of cancer might be related to dampened immunity. Host immunity recognizes nascent malignant cells – a process referred to as immune surveillance. Augmenting immune surveillance and suppressing immune escape are crucial in tumor immunotherapy.

Methods

A recombinant plasmid capable of co-expressing granulocyte-macrophage colony- stimulating factor (GM-SCF), interleukin-21 (IL-21), and retinoic acid early transcription factor-1 (Rae-1) was constructed, and its effects determined in a mouse model of subcutaneous liver cancer. Serum specimens were assayed for IL-2 and INF-γ by ELISA. Liver cancer specimens were isolated for Rae-1 expression by RT-PCR and Western blot, and splenocytes were analyzed by flow cytometry.

Results

The recombinant plasmid inhibited the growth of liver cancer and prolonged survival of tumor-loaded mice. Activation of host immunity might have contributed to this effect by promoting increased numbers and cytotoxicity of natural killer (NK) cells and cytotoxic T lymphocytes (CTL) following expression of GM-SCF, IL-21, and Rae-1. By contrast, the frequency of regulatory T cells was decreased, Consequently, activated CTL and NK cells enhanced their secretion of INF-γ, which promoted cytotoxicity of NK cells and CTL. Moreover, active CTL showed dramatic secretion of IL-2, which stimulates CTL. The recombinant expression plasmid also augmented Rae-1 expression by liver cancer cells. Rae-1 receptor expressing CTL and NK cells removed liver cancer.

Conclusions

The recombinant expression plasmid inhibited liver cancer by a mechanism that involved activation of cell-mediated immunity and Rae-1 in liver cancer.

The soluble form of the EIAV receptor encoded by an alternative splicing variant inhibits EIAV infection of target cells

Equine lentivirus receptor 1 (ELR1) has been identified as the sole receptor for equine infectious anemia virus (EIAV) and is a member of the tumor necrosis factor receptor (TNFR) superfamily. In addition to the previously described membrane-associated form of ELR1, two other major alternative splicing variant mRNAs were identified in equine monocyte-derived macrophages (eMDMs). One major spliced species (ELR1-IN) contained an insertion of 153 nt, which resulted in a premature stop codon situated 561 nt upstream of the predicted membrane spanning domain. The other major species (ELR1-DE) has a deletion of 109 nt that causes a shift of the open reading frame and generates a stop codon 312 nt downstream. Because ELR1-DE presumably encodes a peptide of a mere 23 residues, only ELR1-IN was further analyzed. The expression of a soluble form of ELR1 (sELR1) by ELR1-IN was confirmed by Western blot and immunofluorescence analyses. Similar to ELR1, the transcription level of ELR1-IN varied among individual horses and at different time points in the same individuals. The ratio of ELR1-IN mRNA species to ELR1 mRNA was approximately 1∶2.5. Pre-incubation of the recombinant sELR1 with EIAV significantly inhibited EIAV infection in equine macrophages, the primary in vivo target cell of the virus. Fetal equine dermal (FED) cells are susceptible to EIAV in vitro, and the replication of EIAV in FED cells transiently transfected with ELR1-IN was markedly reduced when compared with replication in cells transfected with the empty vector. Finally, the expression levels of both forms of the EIAV receptor were significantly regulated by infection with this virus. Taken together, our data indicate that sELR1 acts as a secreted cellular factor that inhibits EIAV infection in host cells.