Antigen-presenting Ability Of Dendritic Cells Research Articles

Co-delivering irinotecan and imiquimod by pH-responsive micelle amplifies anti-tumor immunity against colorectal cancer

Irinotecan (IRT), a classic clinical chemotherapeutic agent for treating colorectal cancer, has been found to induce immunogenic cell death (ICD) while exerting cytotoxicity in tumor cells. This effect is likely to be amplified in combination with immune modulators. Unfortunately, free drugs without targeting capacity would receive poor outcomes and strong side effects. To address these issues, in this work, an acid-sensitive micelle based on an amphiphilic poly(β-amino ester) derivative was constructed to co-deliver IRT and the immune adjuvant imiquimod (IMQ), termed PII. PII kept stable under normal physiological conditions. After internalization by tumor cells, PII dissociated in acidic lysosomes and released IRT and IMQ rapidly. In the CT26 tumor mouse model, PII increased the intra-tumoral SN38 (the active metabolite of IRT) and IMQ concentrations by up to 9.39 and 3.44 times compared with the free drug solution. The tumor inhibition rate of PII achieved 87.29%. This might profit from that IRT induced ICD, which promoted dendritic cells (DCs) maturation and intra-tumoral infiltration of CD8+ T cells. In addition, IMQ enhanced the antigen presenting ability of DCs and stimulated tumor associated macrophages to secrete tumor-killing cytokines. PII provided an effective strategy to combat colorectal cancer by synergy of chemotherapy and immunoregulation.

Generation of antigen-specific T lymphocytes targeting Wilms tumor 1 using activated B cells

In order to develop a therapeutic target for T cells, it is necessary to amplify T cells and increase activity through antigen-presenting cells (APCs) expressing an intracellular cancer antigen. Although dendritic cells are frequently used as APCs, producing dendritic cells is costly and time-consuming. In addition, as dendritic cells are attached cells, they are not suitable for mass production for use as immune cell therapy. On the other hand, B cells are non-adherent floating cells, and thus can easily be cultured in suspension systems. As such, B cells can be considered as suitable substance cells for the development of immune cell therapeutics.B cells lack the antigen-presenting ability of dendritic cells. Therefore, to use B cells as APCs, we previously reported a technology that can be used which simply and effectively produces anti-viral T cells in vitro by activating B cells with α-galactosylceramide (α-GalCer). To apply this technology to anti-cancer treatment, Wilms tumor 1, the most representative cancer antigen expressed in various cancers, was selected. Wilms tumor 1 (WT1) was used to produce anti-cancer (anti-WT1) T cells using active B cells as APCs, and their respective activities were investigated.

Blocking DCIR mitigates colitis and prevents colorectal tumors by enhancing the GM-CSF-STAT5 pathway.

Dendritic cell immunoreceptor (DCIR; Clec4a2), a member of the C-type lectin receptor family, plays important roles in homeostasis of the immune and bone systems. However, the intestinal role of this molecule is unclear. Here, we show that dextran sodium sulfate (DSS)-induced colitis and azoxymethane-DSS-induced intestinal tumors are reduced in Clec4a2-/- mice independently of intestinal microbiota. STAT5 phosphorylation and expression of Csf2 and tight junction genes are enhanced, while Il17a and Cxcl2 are suppressed in the Clec4a2-/- mouse colon, which exhibits reduced infiltration of neutrophils and myeloid-derived suppressor cells. Granulocyte-macrophage colony-stimulating factor (GM-CSF) administration ameliorates DSS colitis associated with reduced Il17a and enhanced tight junction gene expression, whereas anti-GM-CSF exacerbates symptoms. Furthermore, anti-NA2, a ligand for DCIR, ameliorates colitis and prevents colorectal tumors. These observations indicate that blocking DCIR signaling ameliorates colitis and suppresses colonic tumors, suggesting DCIR as a possible target for the treatment of these diseases.

Activation of Cellular Players in Adaptive Immunity via Exogenous Delivery of Tumor Cell Lysates.

Tumor cell lysates (TCLs) are a good immunogenic source of tumor-associated antigens. Since whole necrotic TCLs can enhance the maturation and antigen-presenting ability of dendritic cells (DCs), multiple strategies for the exogenous delivery of TCLs have been investigated as novel cancer immunotherapeutic solutions. The TCL-mediated induction of DC maturation and the subsequent immunological response could be improved by utilizing various material-based carriers. Enhanced antitumor immunity and cancer vaccination efficacy could be eventually achieved through the in vivo administration of TCLs. Therefore, (1) important engineering methodologies to prepare antigen-containing TCLs, (2) current therapeutic approaches using TCL-mediated DC activation, and (3) the significant sequential mechanism of DC-based signaling and stimulation in adaptive immunity are summarized in this review. More importantly, the recently reported developments in biomaterial-based exogenous TCL delivery platforms and co-delivery strategies with adjuvants for effective cancer vaccination and antitumor effects are emphasized.

Inhibition of the antigen-presenting ability of dendritic cells by non-structural protein 2 of influenza A virus

Influenza A viruses (IAV), including human IAV and avian IAV (H9N2 subtype), are recurring of influenza outbreaks worldwide in a wide range of mammalian and avian species. Dendritic cells (DCs) are specialised antigen presenting cells. Although DCs can take up IAV and transmit it to other cells, it still unclear why DCs do not effectively present IAV antigens. In this study, we found that Non-structural protein 2 (NS2) of IAV inhibited the maturation and antigen-presenting ability of DCs. We then examined a potential involvement of microRNAs (miRNAs). Analyses of avian DCs stimulated with avian IAV identified 9 upregulated and 10 downregulated miRNAs. However, nearly none microRNA has been significantly altered by NS2 stimulation. Moreover, we found that NS2 binds to exportin 5 (Xpo5), which inhibited miRNA biogenesis. Thus, hijacking of the miRNA biogenesis pathway appears to be one mechanism by which NS2 impairs antigen presentation. Furthermore, we found that NS2 directly interacts with interferon regulatory factor 3, which also inhibits the antigen-presenting ability of DCs. These results thus indicate that NS2-mediated impairment of antigen presentation by DCs might be a mechanism that contributes to the prevalence of the influenza virus.

Development of a Dendritic Cell/Tumor Cell Fusion Cell Membrane Nano-Vaccine for the Treatment of Ovarian Cancer.

Ovarian cancer (OC) is a malignant tumor that seriously affects women’s health. In recent years, immunotherapy has shown great potential in tumor treatment. As a major contributor of immunotherapy, dendritic cells (DCs) - based tumor vaccine has been demonstrated to have a positive effect in inducing immune responses in animal experiments. However, the effect of tumor vaccines in clinical trials is not ideal. Therefore, it is urgent to improve the existing tumor vaccines for tumor treatment. Here, we developed a fusion cell membrane (FCM) nano-vaccine FCM-NPs, which is prepared by fusing DCs and OC cells and coating the FCM on the poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) loaded with the immune adjuvant CpG-oligodeoxynucleotide (CpG-ODN). The fusion process promoted the maturation of DCs, thus up-regulating the expression of costimulatory molecule CD80/CD86 and accelerating lymph node homing of DCs. Furthermore, FCM-NPs has both the immunogenicity of tumor cells and the antigen presenting ability of DCs, it can stimulate naive T lymphocytes to produce a large number of tumor-specific cytotoxic CD8+ T lymphocytes. FCM-NPs exhibited strong immuno-activating effect both in vitro and in vivo. By establishing subcutaneous transplanted tumor model, patient-derived xenograft tumor model and abdominal metastatic tumor model, FCM-NPs was proved to have the effect of delaying the growth and inhibiting the metastasis of OC. FCM-NPs is expected to become a new tumor vaccine for the treatment of ovarian cancer.

Роль тромбоцитов в формировании иммунологической толерантности при привычном выкидыше

Objective of the Review: Аnalysis of literature and summarizing of data on the participation of platelets in the formation of immunological tolerance during the physiological pregnancy and recurrent miscarriage. Key points. Platelet-derived soluble factors determine their involvement in the endocrine regulation of the placenta, initiate and maintain trophoblast invasion. Platelets are able to influence the balance of M1 and M2 macrophages, inhibit the cytotoxic potential of NK cells and the antigen-presenting ability of dendritic cells. The interaction of platelets with regulatory T cells initiates the recruitment of lymphocyte cells to the site of inflammation and their activation. It has been shown that the differentiation of immune cells and changes in their functional activity, aimed at creating conditions favorable for prolonging pregnancy, are largely determined by both platelet-derived soluble factors and the formation of platelet-leukocyte complexes. Conclusion. Platelets and products of their activation play an important role in creating the conditions necessary for the onset of pregnancy and its prolongation to full term. The functional state of platelets determines the success of placentation both directly (through the control of hemodynamic parameters in the placental vessels, increased invasiveness of the extracellular trophoblast, the effect on the endocrine background) and indirectly by modulating the functions of decidual immune cells, which determines their contribution in the implementation of idiopathic pregnancy loss. Keywords: platelets, platelet-leukocyte interaction, immunoregulation, recurrent abortion, pregnancy loss.

A Carbonic Anhydrase IX (CAIX)-Anchored Rhenium(I) Photosensitizer Evokes Pyroptosis for Enhanced Anti-Tumor Immunity.

An ideal cancer treatment should not only destroy primary tumors but also improve the immunogenicity of the tumor microenvironment to achieve a satisfactory anti-tumor immune effect. We designed a carbonic anhydrase IX (CAIX)-anchored rhenium(I) photosensitizer, named CA-Re, that not only performs type-I and type-II photodynamic therapy (PDT) with high efficiency under hypoxia (nanomolar-level phototoxicity), but also evokes gasdermin D (GSDMD) mediated pyroptotic cell death to effectively stimulate tumor immunogenicity. CA-Re could disrupt and self-report the loss of membrane integrity simultaneously. This promoted the maturation and antigen-presenting ability of dendritic cells (DCs), and fully activated T cells dependent adaptive immune response in vivo, eventually eliminating distant tumors at the same time as destroying primary tumors. To the best of our knowledge, CA-Re is the first metal complex-based pyroptosis inducer.

High salt diet accelerates the progression of murine lupus through dendritic cells via the p38 MAPK and STAT1 signaling pathways

The increased incidence of systemic lupus erythematosus (SLE) in recent decades might be related to changes in modern dietary habits. Since sodium chloride (NaCl) promotes pathogenic T cell responses, we hypothesize that excessive salt intake contributes to the increased incidence of autoimmune diseases, including SLE. Given the importance of dendritic cells (DCs) in the pathogenesis of SLE, we explored the influence of an excessive sodium chloride diet on DCs in a murine SLE model. We used an induced lupus model in which bone marrow-derived dendritic cells (BMDCs) were incubated with activated lymphocyte-derived DNA (ALD-DNA) and transferred into C57BL/6 recipient mice. We observed that a high-salt diet (HSD) markedly exacerbated lupus progression, which was accompanied by increased DC activation. NaCl treatment also stimulated the maturation, activation and antigen-presenting ability of DCs in vitro. Pretreatment of BMDCs with NaCl also exacerbated BMDC-ALD-DNA-induced lupus. These mice had increased production of autoantibodies and proinflammatory cytokines, more pronounced splenomegaly and lymphadenopathy, and enhanced pathological renal lesions. The p38 MAPK–STAT1 pathway played an important role in NaCl-induced DC immune activities. Taken together, our results demonstrate that HSD intake promotes immune activation of DCs through the p38 MAPK–STAT1 signaling pathway and exacerbates the features of SLE. Thus, changes in diet may provide a novel strategy for the prevention or amelioration of lupus or other autoimmune diseases.

Abnormal Activation of Myeloid Dendritic Cells in JORRP Patients and Associated with Disease Activity

BackgroundRepresenting the first line of host defense against virus infections and an essential link between innate and adaptive immune response, the role of dendritic cells (DCs) in peripheral blood of juvenile-onset recurrent respiratory papillomatosis (JORRP) patients and association with disease activity were still not established. Materials and MethodsIn our present study, 28 JORRP patients and 28 age and sex matched healthy controls were enrolled. The percentage, phenotype and cytokine secretion of DC and was measured by flow cytometry. Plasma cytokine were detected by the enzyme-linked immunosorbent assay (ELISA). ResultsWe found that the percentage of myeloid DC (mDC) was significantly lower in JORRP patients compared to healthy controls and was negatively correlated with interval times, but not surgical times or disease onset. Moreover, the activation marker, CD40 and CD86 was significantly up-regulated on the surfaces of mDC in JORRP patients compared with healthy controls. Neither the percentage nor activation of plasmacytoid DC (pDC) showed statistical difference between JORRP patients and healthy controls. HLA-DR expression on both mDC and pDC was down-regulated in JORRP group and negatively correlated with surgical times. Antigen presenting ability of DC was greatly impaired in JORRP patients of higher number of operations and shorter interval time. Plasma IL-10 as well as IL-10 secreted by mDC was higher in JORRP patients compared with healthy control. Finally, we detected an up-regulated TLR2 and TLR4 expression on mDCs and TLR4 expression was positively correlated with HLA-DR expression on mDC of JORRP patients. ConclusionOur results demonstrate an abnormal TLR2 and TLR4 expression in mDCs may contribute to suppressive immune response to HPV6 or HPV11 infection and associated with disease activity in JORRP patients.

Gel Phase 1,2-Distearoyl-sn-glycero-3-phosphocholine-Based Liposomes Are Superior to Fluid Phase Liposomes at Augmenting Both Antigen Presentation on Major Histocompatibility Complex Class II and Costimulatory Molecule Display by Dendritic Cells in Vitro.

Lipid-based nanoparticles have in recent years attracted increasing attention as pharmaceutical carriers. In particular, reports of them having inherent adjuvant properties combined with their ability to protect antigen from degradation make them suitable as vaccine vectors. However, the physicochemical profile of an ideal nanoparticle for vaccine delivery is still poorly defined. Here, we used an in vitro dendritic cell assay to assess the immunogenicity of a variety of liposome formulations as vaccine carriers and adjuvants. Using flow cytometry, we investigated liposome-assisted antigen presentation as well as the expression of relevant costimulatory molecules on the cell surface. Cytokine secretion was further evaluated with an enzyme-linked immunosorbent assay (ELISA). We show that liposomes can successfully enhance antigen presentation and maturation of dendritic cells, as compared to vaccine fusion protein (CTA1-3Eα-DD) administered alone. In particular, the lipid phase state of the membrane was found to greatly influence the vaccine antigen processing by dendritic cells. As compared to their fluid phase counterparts, gel phase liposomes were more efficient at improving antigen presentation. They were also superior at upregulating the costimulatory molecules CD80 and CD86 as well as increasing the release of the cytokines IL-6 and IL-1β. Taken together, we demonstrate that gel phase liposomes, while nonimmunogenic on their own, significantly enhance the antigen-presenting ability of dendritic cells and appear to be a promising way forward to improve vaccine immunogenicity.

Genome-wide profiling of microRNAs reveals novel insights into the interactions between H9N2 avian influenza virus and avian dendritic cells.

The antigen-presenting ability of dendritic cells (DCs) plays an important and irreplaceable role in recognising and clearing viruses. Antiviral responses must rapidly defend against infection while minimising inflammatory damage, but the mechanisms that regulate the magnitude of response within an infected cell are not well understood. MicroRNAs (microRNAs), small non-coding RNAs, can regulate mouse or avian DCs to inhibit the infection and replication of avian influenza virus (AIV). Here, we performed a global analysis to understand how avian DCs respond to H9N2 AIV and provide a potential mechanism to explain how avian microRNAs can defend against H9N2 AIV replication. First, we found that both active and inactive H9N2 AIV enhanced the ability of DCs to present antigens and activate T lymphocytes. Next, total microarray analyses suggested that H9N2 AIV stimulation involved protein localisation, nucleotide binding, leucocyte transendothelial migration and MAPK signalling. Moreover, we constructed 551 transcription factor (TF)-miRNA-mRNA loops based on the above analyses. Furthermore, we found that the haemagglutinin (HA) fragment, neither H5N1-HA or H9N2-HA, could not activate DCs, while truncated HA greatly increased the immune function of DCs by activating ERK and STAT3 signalling pathways. Lastly, our results not only suggested that gga-miR1644 targets muscleblind-like protein 2 (MBNL2) to enhance the ability of avian DCs to inhibit virus replication, but also suggested that gga-miR6675 targets the nuclear localisation sequence of polymerase basic protein 1 (PB1) to trigger the silencing of PB1 genes, resulting in the inhibition of H9N2 AIV replication. Altogether, our innovative study will shed new light on the role of avian microRNAs in evoking avian DCs and inhibiting virus replication.

The immune mechanism of Mycoplasma hyopneumoniae 168 vaccine strain through dendritic cells

BackgroundMycoplasma hyopneumoniae (Mhp) causes porcine enzootic pneumonia, a disease that cause major economic losses in the pig industry. Dendritic cells (DCs), the most effective antigen-presenting cells, are widely distributed beneath respiratory epithelium, DCs uptake and present antigens to T cells, to initiate protective immune responses in different infections. In this study, we investigated the role of porcine DCs in vaccine Mhp-168 exposure.ResultsThe antigen presenting ability of DCs were improved by vaccine Mhp-168 exposure. DCs could activate T-cell proliferation by up-regulating the antigen presenting molecule MHCII expression and co-stimulatory molecule CD80/86. However, the up-regulation of IL-10 and accompany with down-regulation of IFN-γ gene level may account for the limitation of attenuated Mhp-168 strain use as vaccine alone.ConclusionThese findings are benefit for exploring the protection mechanisms and the possible limitations of this attenuated Mhp-168 vaccine.

Effects of Mycoplasma hyopneumoniae on porcine nasal cavity dendritic cells

Mycoplasma hyopneumoniae (Mhp) is the primary etiological agent responsible for swine enzootic pneumonia (EP), a disease that cause tremendous economic losses all over the swine industry. Dendritic cells (DCs), the most effective antigen-presenting cells, are widely distributed beneath respiratory epithelium. DCs uptake and present antigens to T cells, to initiate protective immune responses or generate immune-mediated pathology in different infections. In this study, we investigated the changes in the different DCs subpopulations, T cells and SIgA positive cells counts in porcine nasal cavity after long time Mhp infection. We further evaluated the role of porcine DCs in Mhp exposure. Our results showed that the number of SLA-II-DR+SWC3a+DCs, SLA-II-DR+CD11b+ DCs, T cells, SIgA positive cells in nasal cavity were decreased after Mhp 28 days infection in vivo experiment. The antigen presenting ability of DCs were inhibited by Mhp exposure. DCs couldn’t activate T-cell proliferation by down-regulating the antigen presenting molecule CD1a expression and promoting high level of IL-10 production. Further more, the expression levels of IL-12 and IFN-γ in DCs were decreased, suggesting that DCs favour for Th2 immune response development after Mhp exposure in vitro. Taken together, Mhp infection impairs the immune function which allows the persistence of Mhp and cause predispose pigs to secondary infections. The decline of DCs presentation ability is the reason why dysfunction and persistence in Mhp infection. These findings are benefit for exploring the pathogenic mechanisms of Mhp in pigs.

Vasoactive Intestinal Peptide Promotes Immune Escape of MKN45 Cells by Inhibiting Antigen-Presenting Molecules of Dendritic Cells In Vitro

To investigate vasoactive intestinal peptide (VIP) effect on dendritic cells (DCs) to gastric cancer (GC) cells in vitro involving immune escape mechanism of GC, we observed DC-SIGN (CD209), Ii chain (CD74), MHC-II and collaborative costimulatory molecules CD40, CD80, CD86 expressions in DCs, which co-incubated with GC cells and VIP. Human umbilical cord blood (HUCB) were obtained from healthy volunteers and human mononuclear cells were isolated from HUCB by density gradient centrifugation. Monocytes were purified from mononuclear cells using adherence separation and were treated with recombinant human granulocyte–macrophage colony-stimulating factor (rh GM-CSF), recombinant human interleukin-4 (rh IL-4) to induce immature monocyte-derived DCs (moDCs). Recombinant human tumor necrosis factor (rh TNF-α) was added on the 5th day to induce mature moDCs. Mature moDCs were collected on the 10th day, and co-incubated with MKN45, VIP and mannan, respectively. CD1a and CD83 expressions were detected by immunocytochemistry. VIP, VPAC1, CD209, CD74, MHC-II, CD40, CD80 and CD86 expressions of DCs were detected by immunocytochemistry and RT-PCR. VPAC1 was detected in DCs, but VIP did not detected in DCs. When DCs were co-incubated with MKN45 cells, MKN45 cells could inhibit DCs’ expressions of CD209, CD74, MHC-II, CD40, CD80 and CD86 in the mRNA and protein levels (p < 0.05), and VIP could further inhibit CD209, CD74, MHC-II, CD40, CD80 and CD86 expressions of DCs in the mRNA and protein levels (p < 0.05). The inhibition could not been reversed by mannan. CD209 was positively correlated with CD74, MHC-II, CD40, CD80 and CD86 in mRNA level and protein expression intensity in DCs. VIP could inhibit CD209, CD74, MHC-II, CD40, CD80 and CD86 expressions of DCs, and inhibit antigen-presenting ability of DCs. VIP may promote immune escape of GC by inhibiting CD209, CD74, MHC-II, CD40, CD80 and CD86 expressions of DCs.

Intralesional Rose Bengal in melanoma elicits tumor immunity via HMGB1

Intralesional (IL) therapy is under investigation to treat dermal and subcutaneous metastatic cancer. Rose Bengal (RB) is a staining agent that was originally used by ophthalmologists and in liver function studies. Previously, IL injection of RB induced regression of injected and uninjected tumors in murine models. However, the relevant mechanism is yet unknown. In this study, we used an OVA-expressing B16 melanoma murine model and found that IL RB treatment led to increased tumor-specific T cells with memory characteristics. CD8+ T cell are crucial for tumor-specific response elicited by IL RB. IL RB therapy also increased antigen-specific T cell proliferation and enhanced tumor regression. In addition, IL RB facilitated dendritic cells (DCs) infiltrating lymph nodes draining from tumor. Incubation of melanoma cells with RB led to necrosis and the release of High Mobility Group Box 1 (HMGB1), which activated DCs via up-regulation of CD40 expression. The blockade of HMGB1 significantly reduced the antigen-presenting ability of DCs. To determine whether this mechanism was relevant in patients treated with IL RB, we performed a pilot clinical study in melanoma patients (NCT01760499). IL RB led to tumor regression in both RB-injected and uninjected lesions, associated with an increase in circulating T cells. Increased tumor-specific response was found from those circulating T cells of 5 out of 7 tested patients after IL RB treatment. HMGB1 levels in patient sera were also elevated. Together, these results reveal a clinically relevant immunoadjuvant pathway triggered by tumor cell death secondary to ablation with RB.

Abstract 3615: IL-6/STAT3-dependent immunosuppressive function of tumor-infiltrating dendritic cells in colorectal cancer

Abstract Introduction Immunosuppression in tumor microenvironments is one of the critical issues for cancer immunotherapy. To develop more effective treatment, it is essential to overcome the dysfunction of immunity in cancer patients. Recently, it has been demonstrated that myeloid derived suppressor cells (MDSCs) have crucial roles for such immunosuppression. In the current reports, it was indicated that activation of STAT3 was required for immunosuppressive function of human MDSCs. In this study, we focused on IL-6/STAT3-signaling pathway in human monocyte-derived dendritic cells (DCs), and investigated the effects of IL-6 on antigen-presenting ability of DCs. Materials and Methods Tumor-infiltrating myeloid cells and PBMCs were collected from specimen of patients with colorectal cancers. Surface molecules , such as HLA-DR, of the cells were investigated by flowcytometry. Then, the surface molecules of monocyte-derived DCs from healthy volunteers were evaluated after the stimulation with IL-6 in vitro. IL-6-treated DCs were co-cultured with autologous T cells stimulated by using anti-CD3 antibody and cytokine production levels were investigated by ELISA. MAGE-A4-specific CD4+ T cells were generated from PBMCs ofhealthy healthy volunteers in vitro and co-cultured with IL-6-pretreated DCs in the presence of MAGE-A4 antigen. Cytokine production by antigen specific T cells were measured by ELISA. Results In this study, we found that expression levels of HLA-DR and CD86 are down regulated in tumor infiltrating CD11c+CD14+ DCs compared with peripheral monocytes. In addition, we confirmed that HLA-DR and CD86 expressions were significantly reduced by IL-6 treatment of CD11c+CD14+ DCs in vitro. The reduction of HLA-DR and CD86 expression levels were remarkably blocked in the presence of STAT3 inhibitor. IFN-γ production by T cells after TCR-stimulation was suppressed in the presence of IL-6-treated DCs compared with control DCs. Moreover, activation of MAGE-A4 antigen-specific CD4+ T cells were remarkably reduced by IL-6-treatment of DCs. Discussion Previously, it was reported that CD14+HLA-DRlow/- cells increased in peripheral blood of cancer patients and that these cells were an important population for immunosuppression. In this study, we demonstrated that IL-6/STAT3-signaling cascade was one of the regulating factors for surface expression levels of HLA-DR on DCs. In addition, we confirmed that IL-6-treatment significantly suppressed the antigen presentation by DCs for cancer antigen-specific CD4+ T cells. Generally, MDSCs were known to induce several immunosuppressive and tumor promoting factors such as VEGF, ARG1, and COX2. We are now investigating target molecules of IL-6 for dysfunction of DCs in tumor microenvironments. Conclusion IL-6/STAT3 signaling pathway regulates immunosuppressive function of human DCs, which would be a promising target for improving the effects of cancer immunotherapy. Citation Format: Yosuke Ono, Jyunya Ohtake, Shun Kaneumi, Kazutaka Masuko, Kentaro Sumida, Takuto Kishikawa, Satoshi Terada, Toshiyuki Kita, Norihiko Takahashi, Akinobu Taketomi, Hidemitsu Kitamura. IL-6/STAT3-dependent immunosuppressive function of tumor-infiltrating dendritic cells in colorectal cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3615. doi:10.1158/1538-7445.AM2014-3615

Activation of IL-6/STAT3-signaling cascade induces suppression of antigen presentation by human dendritic cells (TUM4P.917)

Abstract Immunosuppression in tumor microenvironments is one of the critical issues for cancer immunotherapy. We have been demonstrated that IL-6, a pleiotropic cytokine that regulate the growth, differentiation and survival of a variety of cells, significantly inhibited maturation of murine dendritic cells (DCs) via STAT3 activation both in vitro and in vivo. In this study, we focused on IL-6/STAT3-signaling cascade in human dendritic cells (DCs), and investigated the effects of IL-6 on antigen-presenting ability of DCs. Surface HLA class I, HLA class II, and costimulatory molecules of human DCs were evaluated after the stimulation with IL-6 in vitro. As a result, HLA-DR and CD86 expressions were significantly reduced by IL-6 treatment of human DCs. The reduction was remarkably blocked in the presence of STAT3 inhibitor. In addition, IFN-γ production by T cells after TCR-stimulation was significantly suppressed in the presence of IL-6-treated DCs compared with control DCs. Moreover, we found that activation of antigen-specific CD4+ T cells by DCs was remarkably reduced by the IL-6-treatment. In this study, we demonstrated that IL-6/STAT3-signaling cascade was one of the regulating factors for antigen presentation of DCs. From these findings suggest that IL-6/STAT3 signaling cascade regulates immunosuppressive function of human DCs, which would be a promising target for improving the effects of cancer immunotherapy.

Effects of ceftriaxone‐induced intestinal dysbacteriosis on dendritic cells of small intestine in mice

Intestinal microflora plays a pivotal role in the development of the innate immune system and is essential in shaping adaptive immunity. Dysbacteriosis of intestinal microflora induces altered immune responses and results in disease susceptibility. Dendritic cells (DCs), the professional antigen-presenting cells, have gained increasing attention because they connect innate and adaptive immunity. They generate both immunity in response to stimulation by pathogenic bacteria and immune tolerance in the presence of commensal bacteria. However, few studies have examined the effects of intestinal dysbacteriosis on DCs. In this study, changes of DCs in the small intestine of mice under the condition of dysbacteriosis induced by ceftriaxone sodium were investigated. It was found that intragastric administration of ceftriaxone sodium caused severe dysteriosis in mice. Compared with controls, numbers of DCs in mice with dysbacteriosis increased significantly (P = 0.0001). However, the maturity and antigen-presenting ability of DCs were greatly reduced. In addition, there was a significant difference in secretion of IL-10 and IL-12 between DCs from mice with dysbacteriosis and controls. To conclude, ceftriaxone-induced intestinal dysbacteriosis strongly affected the numbers and functions of DCs. The present data suggest that intestinal microflora plays an important role in inducing and maintaining the functions of DCs and thus is essential for the connection between innate and adaptive immune responses.

Time-dependent persistence of enhanced immune response by a potential probiotic strain Lactobacillus paracasei subsp. paracasei NTU 101

The possible time-dependent role of lactic acid bacteria (LAB) in immunomodulation was investigated in BALB/c mice fed daily with Lactobacillus paracasei subsp. paracasei NTU 101 (10 8 colony forming units) for 3, 6, and 9 weeks, and following feeding with Lactobacillus-free food for a further 7 days. We observed up-regulation of the antigen-presenting ability of dendritic cells, and expression of natural killer group-2 D (NKG2D) molecules capable of trigger natural killer cell-mediated cytotoxicity. Lymphocyte proliferation and antibody production were also significantly increased in mice after treatment. Innate and adaptive immunity remained constant even at the most protracted feeding time, indicative of the time dependence of the bacterial-mediated enhanced immunity. To better correlate intestinal microflora with immunity, the intestinal contents of probiotics and harmful microorganisms were determined. Results showed an altered intestinal microflora, with increases in bifidobacteria and lactobacilli and a decreased content of Clostridium perfringens after feeding with L. paracasei subsp. paracasei NTU 101. It is possible that persistent activation of immunity might be induced by intestinal probiotics.