Activated human CD4+ T cells induced by dendritic cell stimulation are most sensitive to transforming growth factor-beta: implications for dendritic cell immunization against cancer

Compound 511 ameliorates MRSA-induced lung injury by attenuating morphine-induced immunosuppression in mice via PI3K/AKT/mTOR pathway

BACKGROUND

Opioids are widely used in clinical practice. However, their long-term administration causes respiratory depression, addiction, tolerance, and severe immunosuppression. Traditional Chinese medicine (TCM) can alleviate opioid-induced adverse effects. Compound 511 is particularly developed for treating opioid addiction, based on Jiumi Liangfang, an ancient Chinese drug treatment and rehabilitation monograph completed in 1833 A.D. It is an herbal formula containing eight plants, each of them contributing to the overall pharmacological effect of the product: Panax ginseng C. A. Meyer (8.8%), Astragalus membranaceus (Fisch.) (18.2%), Datura metel Linn. (10.95%), Corydalis yanhusuo W. T. Wang (14.6%), Acanthopanar gracilistμlus W. W. Smith (10.95%), Ophiopogon japonicus (Linn. f.) Ker-Gawl. (10.95%), Gynostemma pentaphyllum (Thunb.) Makino (10.95%), Polygala arvensis Willd. (14.6%). This formula effectively ameliorates opioid-induced immunosuppression. However, the underlying mechanism remains unclear.

PURPOSE

To reveal the effects of Compound 511 on the immune response of morphine-induced immunosuppressive mice and their potential underlying molecular mechanism. This study provides information for a better clinical approach and scientific use of opioids.

METHODS

Immunosuppression was induced in mice by repeated morphine administration. Th1/Th2/Th17/Treg cell levels were measured using flow cytometry. Splenic transcription factors of Th1/Th2/Th17/Treg and outputs of the regulatory PI3K/AKT/mTOR signaling pathway were determined. Subsequently, methicillin-resistant Staphylococcus aureus (MRSA) was administered intranasally to morphine-induced immunosuppressive mice pretreated with Compound 511. Their lung inflammatory status was assessed using micro-computer tomography (CT), hematoxylin and eosin (H&E) staining, and enzyme-linked immunosorbent assay (ELISA).

RESULTS

Compared to morphine, Compound 511 significantly decreased the immune organ indexes of mice, corrected the Th1/Th2 and Treg/Th17 imbalance in the immune organs and peripheral blood, reduced the mRNA levels of FOXP3 and GATA3, and increased those of STAT3 and T-bet in the spleen. It improved immune function and reduced MRSA-induced lung inflammation.

CONCLUSION

Compound 511 ameliorates opioid-induced immunosuppression by regulating the balance of Th1/Th2 and Th17/Treg via PI3K/AKT/mTOR signaling pathway. Thus, it effectively reduces susceptibility of morphine-induced immunosuppressive mice to MRSA infection.

Myrothecine A modulates the proliferation of HCC cells and the maturation of dendritic cells through downregulating miR-221

Myrothecine A, characterized from the extracts of myrothecium roridum strain IFB-E012, isolated as endophytic fungi found in the traditional Chinese medicinal plant Artemisia annua. Here we investigated its roles on anti-tumor and immune regulation in vitro. Dendritic cells (DCs) are the most potent antigen presenting cells in immune responses. Recent studies have indicated that miRNAs are indispensable in regulating the development, differentiation, maturation and function of DC. MiR-221, acted as an oncogene, is an important regulator in cancer development by binding to 3' untranslated regions (3' UTR) of target mRNA. Here, we investigated whether myrothecine A could inhibit cell proliferation in hepatocellular carcinoma (HCC) cell line SMMC-7721 by regulating miR-221. The HCC cells were treated with myrothecine A at different concentration, and the cell growth ability was measured by MTT assay. Then we observed whether myrothecine A could affect the maturation of DC by regulating miR-221. The HCC cell line was co-cultured with immature DC from mice bone marrow, and the levels of CD86 and CD40 was detected by FCM. Our results showed that myrothecine A could rescue miR-221-induced cell proliferation and influence the protein level of p27 by inhibiting the expression of miR-221. In addition, myrothecine A could enhance the expression of CD86 and CD40 by reversing the function of miR-221. Therefore, myrothecine A may be acted as an anti-tumor drug to promote the maturation of DC in the microenvironment of hepatocellular carcinoma.

Cellular and functional characterization of immunoresistant human glioma cell clones selected with alloreactive cytotoxic T lymphocytes reveals their up-regulated synthesis of biologically active TGF-beta

Two immunoresistant (IR) glioma cell variants, 13-06-IR29 and 13-06-IR30, were cloned from 13-06-MG glioma cell populations after receiving continuous immunoselective pressure from multiple alloreactive cytotoxic T lymphocyte (aCTL) preparations. Reapplication of aCTL immunoselective pressure to the IR clones, displaying a partial regain in sensitivity to aCTL after removal of the selective pressure, restored the resistance. The IR variants exhibited cross-resistance to non-human leukocyte antigen (HLA)-restricted effector cells and gamma-irradiation, but not to carmustine. The IR clones were characterized for factors that might contribute to the immunoresistance. The aCTL adhesion to extracellular matrix extracts derived from either the IR clones or the parental cells was similar and not impaired. Furthermore, aCTL binding to parental cells and IR clones was equal. Down-regulation of the cell recognition molecules, class I HLA or intercellular adhesion molecule-1 (ICAM-1), that would inhibit their recognition by aCTL was not observed on the IR clones. The down-regulation of Fas by the IR clones correlated with their resistance to FasL-induced apoptosis. HLA-G or FasL that might provide an immunotolerant environment or provide a means of counterattack to aCTL, respectively, were not associated with the IR phenotype. The aCTL, coincubated with the IR clones and parental cells, displayed up-regulation of multiple secreted cytokines. A significant up-regulation of bioactive transforming growth factor (TGF)-beta was observed in the IR clones compared with the parental cells. These data suggest that increased secretion of bioactive TGF-beta may inhibit aCTL lysis of the IR clones. Disruption of the TGF-beta signaling pathway may circumvent the resistance.

Bioregulators as prototypic nontraditional threat agents

Bioregulators are naturally occurring organic compounds that regulate a multitude of biologic processes. Under natural circumstances, bioregulators are synthesized in minute quantities in a variety of living organisms and are essential for physiologic homeostasis. In the wrong hands, these compounds have the capability to be used as nontraditional threat agents that are covered by the prohibitions of the Chemical Weapons Convention and the Biological and Toxin Weapons Convention. Unlike traditional biowarfare/bioterrorism agents that have a latency period of hours to days,the onset of action of bioregulators may occur within minutes after host exposure. Concerns regarding the potential misuse of bioregulators for nefarious purposes relate to the ability of these nontraditional agents to induce profound physiologic effects.

Surgical influence of pancreatectomy on the function and count of circulating dendritic cells in patients with pancreatic cancer

BACKGROUND

Dendritic cells (DCs) are important for an immune surveillance. Myeloid DCs (DC1) are important for an effective antitumor immune system. The function and count of circulating DC1 (cDC1) in hosts with a malignant tumor would be defective. This study focused on analyzing the immunological features of cDC1 in patients with pancreatic cancer during the perioperative period.

MATERIALS AND METHODS

Thirty-two pancreatic cancer patients who underwent pancreatectomy and 18 age-matched healthy individuals as controls were enrolled in this study. The perioperative cDC count, the stimulatory capacity of cDC1 against allogeneic T cells and TGF-beta1 level in the serum were measured. The cDC count was measured at 12 months after the operation.

RESULTS

The preoperative cDC1/cDC2 ratio, cDC1 count, and stimulatory capacity of cDC1 were impaired in patients in comparison to controls (P<0.05). The serum TGF-beta1 level was significantly higher in patients than controls (P<0.001). The stimulatory capacity of cDC1 recovered after pancreatectomy (P<0.05). The serum TGF-beta1 level significantly decreased after the operation (P<0.05); however, they were still significantly higher than controls (P<0.05). Although the cDC1/cDC2 ratio and the cDC1 count did not increase after the pancreatectomy, they recovered as the controls' level at 12 months after the pancreatectomy in disease-free patients (P<0.05) and the serum TGF-beta1 level in those patients at 12 months after the operation significantly decreased compared with those at the postoperative period (P<0.05).

CONCLUSION

Surgical resection of pancreatic cancer could be associated with improved cDC1 function. When a patient remained disease free, the recovery of cDC1 counts was observed approximately 12 months after pancreatectomy. Further strategy will be needed to improve immune function in patients with pancreatic cancer.

Tumor-derived TGFbeta-1 induces dendritic cell apoptosis in the sentinel lymph node

Lymphatic flux from a primary tumor initially flows into a tumor-draining lymph node (LN), the so-called sentinel LN (SLN). Carried by the lymph fluid are a variety of mediators produced by the tumor that can influence immune responses within the SLN, making it a good model with which to investigate tumor-related immunology. For instance, dendritic cell (DC) numbers are reduced in SLNs from melanoma and breast cancer patients. In the present study, we investigated the mechanism by which DC numbers were reduced within SLNs from patients with non-small cell lung cancer. We found that the incidence of apoptosis among DCs was higher in SLNs than in non-SLNs, as were levels of TGFbeta-1. In contrast, levels of TGFbeta-1 mRNA did not differ between SLNs and non-SLNs, but were 30 times higher in tumors than in either LN type. In vitro, incubation for 2 days with TGFbeta-1 induced apoptosis among both cultured DCs and DCs acutely isolated from normal thoracic LNs, effects that were blocked by the TGFbeta-1 inhibitor DAN/Fc chimera. Taken together, these results suggest that tumor-derived TGFbeta-1 induces immunosuppression within SLNs before the movement of tumor cells into the SLNs, thereby facilitating metastasis within those nodes.

Radiation-induced cell death and dendritic cells: potential for cancer immunotherapy?

Dendritic cells are key orchestrators of the immune system. There is considerable interest in their use for treating cancer. Whether they initiate an effective cytotoxic response against antigen-bearing cells, or produce tolerance, depends on the context in which those antigens are presented. Ionising radiation, and the cell death it causes, has several properties that may facilitate such an effective response. A range of in-vitro and in-vivo data supports this, although potential problems exist that may require concurrent strategies.

Sequential delivery of interferon-alpha gene and DCs to intracranial gliomas promotes an effective antitumor response

Effective presentation of tumor antigens by dendritic cells (DCs) is considered to be essential for the induction of antitumor T-cell responses. Apoptotic and necrotic tumors have been noted to be a robust antigen source for DCs. Because glioma cells undergo apoptosis after transfection with the type I interferon (IFN) gene and type I IFNs promote the stimulatory activity of DCs, we hypothesized that transfection of glioma cells with type I IFN genes and provision of DCs would promote particularly effective antitumor activity by both facilitating apoptosis of glioma cells and the presentation of the glioma antigens, thereby inducing specific immune responses against glioma cells. We have previously reported the proof of this hypothesis in vitro and in a subcutaneous tumor model. Here we report an extension of this approach in intracranial (i.c.) gliomas using adenoviral IFN-alpha (Ad-IFN-alpha) vector. Mice bearing day-5 i.c. GL261 glioma received sequential intratumoral (i.t.) delivery of Ad-IFN-alpha and bone marrow-derived syngeneic DCs. This treatment prolonged survival in that nine of 17 animals survived long term (> 60 days versus 0 of 10 control animals). Specific CTL activity was demonstrated following this regimen in the cervical lymph nodes, and the therapeutic efficacy was dependent upon CD8+ cells. Furthermore, these animals were protected against subsequent re-challenge with GL261 gliomas. DCs injected i.t. survived in the tumor and migrated into cervical lymph node. In vitro migration assays revealed the ability of DCs to migrate toward the tumor, suggesting that i.t. injected DCs migrate through the glioma. Taken together, this combination of gene therapy and cellular immunotherapy may be an effective future strategy for treating human gliomas.

Dendritic cell-induced activation of adaptive and innate antitumor immunity

While studying Ag-pulsed syngeneic dendritic cell (DC) immunization, we discovered that surprisingly, unpulsed DCs induced protection against tumor lung metastases resulting from i.v. injection of a syngeneic BALB/c colon carcinoma CT26 or a syngeneic C57BL/6 lung carcinoma LL/2. Splenocytes or immature splenic DCs did not protect. The protection was mediated by NK cells, in that it was abrogated by treatment with anti-asialo-GM1 but not anti-CD8, and was induced by CD1(-/-) DCs unable to stimulate NKT cells, but did not occur in beige mice lacking NK cells. Protection correlated with increased NK activity, and increased infiltration of NK but not CD8(+) cells in lungs of tumor-bearing mice. Protection depended on the presence of costimulatory molecules CD80, CD86, and CD40 on the DCs, but surprisingly did not require DCs that could make IL-12 or IL-15. Unexpectedly, protection sensitive to anti-asialo-GM1 and increased NK activity were still present 14 mo after DC injection. As NK cells lack memory, we found by depletion that CD4(+) not CD8(+) T cells were required for induction of the NK antitumor response. The role of DCs and CD4(+) T cells provides a novel mechanism for NK cell induction and innate immunity against cancer that may have potential in preventing clinical metastases.

Cancer vaccines: between the idea and the reality

Whether vaccines are designed to prepare the immune system for the encounter with a pathogen or with cancer, certain common challenges need to be faced, such as what antigen and what adjuvant to use, what type of immune response to generate and how to make it long lasting. Cancer, additionally, presents several unique hurdles. Cancer vaccines must overcome immune suppression exerted by the tumour, by previous therapy or by the effects of advanced age of the patient. If used for cancer prevention, vaccines must elicit effective long-term memory without the potential of causing autoimmunity. This article addresses the common and the unique challenges to cancer vaccines and the progress that has been made in meeting them. Considering how refractory cancer has been to standard therapy, efforts to achieve immune control of this disease are well justified.

Effective induction of antiglioma cytotoxic T cells by coadministration of interferon-beta gene vector and dendritic cells

As type I interferons (IFNs) enhance the stimulatory activity of dendritic cells (DCs), we hypothesized that transfection of glioma cells with the IFN-beta gene in the presence of DCs would provide particularly effective antitumor activity by both facilitating apoptosis of glioma cells and presenting the resulting glioma antigens to T cell by DCs, thereby inducing specific T-cell responses against glioma cells. A mouse glioma cell line 203G was first transfected with cDNA encoding IFN-beta using cationic liposomes, then cocultured with syngeneic bone marrow-derived DCs and naïve splenic T cells. The 203G cells were almost completely killed following 96-hour coculture with DCs and T cells, and strong tumor-specific cytotoxic T-lymphocyte (CTL) activity accompanied by high level interleukin (IL)-12 and IFN-gamma production was observed in culture. In addition, omission of either IFN-beta gene delivery, DCs or T cells from the coculture completely abrogated the induction of the CTL activity, suggesting that the combination of these components was required to elicit an optimal effect. On the basis of these in vitro data, syngeneic animals bearing subcutaneous 203G tumors received intratumoral injections of IFN-beta gene and DCs. Suppression of the tumor growth by this combinational therapy was superior to treatment with DC or IFN-beta gene solely. This combination may constitute a new therapeutic strategy to induce potent antiglioma immune responses.

Tumor-derived TGF-beta reduces the efficacy of dendritic cell/tumor fusion vaccine

Dendritic cell (DC)-based antitumor vaccine is a novel cancer immunotherapy that is promising for reducing cancer-related mortality. However, results from early clinical trials were suboptimal. A possible explanation is that many tumors secrete immunosuppressive factors such as TGF-beta, which may hamper host immune response to DC vaccine. In this study, we demonstrated that TGF-beta produced by tumors significantly reduced the potency of DC/tumor fusion vaccines. TGF-beta-secreting (CT26-TGF-beta) stable mouse colon cancer cell lines were generated using a retroviral vector expressing TGF-beta. A non-TGF-beta-secreting (CT26-neo) cell line was generated using an empty retroviral vector. The efficacies of DC/tumor fusion vaccines were assessed in vitro and in vivo. DC/CT26-TGF-beta fusion cells failed to induce a strong T cell proliferative response in vitro, mainly due to the effect of TGF-beta on T cell responsiveness rather than DC stimulatory capability. Animals vaccinated with DC/CT26-TGF-beta fusion vaccine had lower tumor-specific CTL activity and had significantly lower survival after tumor challenge as compared with animals immunized with DC/CT26-neo hybrids (45 vs 77%, p < 0.05). Ex vivo exposure of DCs to TGF-beta did not appear to lessen the efficacy of DC vaccine. These data suggest that tumor-derived TGF-beta reduces the efficacy of DC/tumor fusion vaccine via an in vivo mechanism. Neutralization of TGF-beta produced by the fusion cells may enhance the effectiveness of DC-based immunotherapy.

Transforming growth factor-beta induces apoptosis in antigen-specific CD4+ T cells prepared for adoptive immunotherapy

Transforming growth factor-beta (TGF-beta), found at the site of most tumors, has been recognized as one of the mechanisms involved in tumor immunological escape. To evaluate its impact on adoptive immunotherapy against cancer, we examined the susceptibility of tumor-specific T cells to TGF-beta in the setting of these T cells being prepared for adoptive transfer. Hepatitis B virus (HBV)-specific CD4(+) T cells were ex vivo generated by activating with HBV-transfected dendritic cells and selecting with antibodies to CD25 activation molecules, and then expanded with antibodies to CD3/CD28. These T cells expressed higher levels of the type II TGF-beta receptor than nai;ve T cells and exhibited enhanced apoptosis when exposed to TGF-beta. The underlying apoptotic pathway was linked to the dissipation of the mitochondrial inner membrane potential and activation of caspase-9. The absence of caspase-8 activity in TGF-beta-treated T cells suggests that the death receptor system may not be involved in this type of apoptosis. Interleukin-2 (IL-2), which is concomitantly administered with tumor-specific T cells in adoptive immunotherapy, was unable to protect HBV-specific CD4(+) T cells from the pro-apoptotic effect of TGF-beta when added simultaneously with TGF-beta. Interesting, IL-2-pretreated T cells displayed the type II TGF-beta receptor at lower levels and were more resistant to TGF-beta. Together, our findings indicate that the effectiveness of adoptive cancer immunotherapy may be impaired by tumor-derived TGF-beta and appropriate manipulation of exogenous IL-2 might overcome this hurdle.

Selective modification of antigen-specific CD4(+) T cells by retroviral-mediated gene transfer and in vitro sensitization with dendritic cells

Adoptive therapy with antigen-specific T cells is a potential treatment against cancers and viral diseases. To establish a system to modify the genes of these cells to increase their effectiveness, we examined whether the combined use of retroviral vector, which only infects dividing cells, and in vitro sensitization of T cells with antigen-loaded dendritic cells (DCs) could selectively modify antigen-specific T cells with a bcl-2 gene. Human CD4(+) T cells were used as target cells. Autologous DCs transfected with genes of hepatitis B virus (HBV) stimulated a specific T cell proliferation. Importantly, these proliferating T cells were selectively transduced by a bcl-2-retrovirus, and CD25(+) T cells isolated from them contained higher levels of integrated provirus. To select bcl-2-transduced, activated T cells, cells were subjected to interleukin-2 (IL-2) withdrawal. In contrast to CD25(-) and mock-infected CD25(+) T cells, 70% of CD25(+) T cells transduced with bcl-2-retrovirus survived IL-2 withdrawal. These surviving T cells were demonstrated to contain integrated bcl-2 provirus and exhibited HBV-specific proliferation and interferon-gamma secretion. In addition, bcl-2 overexpression protected HBV-specific T cells from transforming growth factor (TGF)-beta-induced cell death. These results demonstrate the feasibility of our strategy in the generation of genetically modified antigen-specific CD4(+) T cells and show that bcl-2-transduced antigen-specific T cells survive IL-2 withdrawal and TGF-beta-induced apoptosis.