The current role of dendritic cells in the progression and treatment of colorectal cancer

Colorectal cancer(CRC)is the third most common cancer and the second leading cause of cancer-related deaths worldwide.Dendritic cells(DCs)constitute a heterogeneous group of antigen-presenting cells that are important for initiating and regulating both innate and adaptive immune responses.As a crucial component of the immune system,DCs have a pivotal role in the pathogenesis and clinical treatment of CRC.DCs cross-present tumor-related antigens to activate T cells and trigger an antitumor immune response.However,the antitumor immune function of DCs is impaired and immune tolerance is promoted due to the presence of the tumor microenvironment.This review systematically elucidates the specific characteristics and functions of different DC subsets,as well as the role that DCs play in the immune response and tolerance within the CRC microenvironment.Moreover,how DCs contribute to the progression of CRC and potential therapies to enhance antitumor immunity on the basis of existing data are also discussed,which will provide new perspectives and approaches for immunotherapy in patients with CRC.

Study on mechanism of increased allergenicity induced by Ara h 3 from roasted peanut using bone marrow-derived dendritic cells

Little information was so far available about allergenic mechanism of the roasted peanut allergens during initial stages of allergy.The purpose of this study was to determine the influence of roasting(150℃,20 min)on biochemical and biological properties of Ara h 3,a major peanut allergen.Allergenicity of roasted peanut emulsion to mice,differences in uptakes between Ara h 3 purified from raw peanuts(named as Ara h 3-Raw)and that purified from roasted peanuts(named as Ara h 3-Roasted)by bone marrow-derived dendritic cells(BMDCs)and the implication of cell surface receptors involving in uptake,and changes in glycosylation and structure of Ara h 3 after roasting were analyzed in this study.This study suggested that roasting increased allergenicity of peanut to BALB/c mice.Maillard reaction and structural changes of Ara h 3 induced by roasting significantly altered the uptake of Ara h 3-Roasted by BMDCs,and modified Ara h 3 fate in processes involved in immunogenicity and hyper allergenicity,indicating that food processing pattern can change food allergenicity.

Dendritic cells in hepatitis C virus infection:Key players in the IFNL3-genotype response

Recently,single nucleotide polymorphisms,in the vicinity of the interferon lambda 3(IFNL3)gene have been identified as the strongest predictor of spontaneous and treatment induced clearance of hepatitis C virus(HCV)infection.Since then,increasing evidence has implicated the innate immune response in mediating the IFNL3 genotype effect.Dendritic cells(DCs)are key to the host immune response in HCV infection and their vital role in the IFNL3 genotype effect is emerging.Reports have identified subclasses of DCs,particularly myeloid DC2s and potentially plasmacytoid DCs as the major producers of IFNL3 in the setting of HCV infection.Given the complexities of dendritic cell biology and the conflicting current available data,this review aims to summarize what is currently known regarding the role of dendritic cells in HCV infection and to placeit into context of what is know about lambda interferons and dendritic cells in general.

Changes of the Transcriptional Levels of Molecules Associated with Endogenous Antigen Processing and Presentation in Porcine Skin-derived Dendritic Cells Infected with PCV2 in vivo

[Objective] This study aimed to investigate the changes of the transcriptional levels of molecules associated with endogenous antigen processing and presenta- tion in porcine skin-derived dendritic cells infected with PCV2 in vivo. [Method] Healthy 40-day-old Landrace piglets were infected with porcine circovirus type 2 （PCV2） and euthanized on the 34, 7rd, 14th, 21st and 35th d post inoculation （DPI）. The porcine skin-derived dendritic cells （DCs） were collected to analyze the transcrip- tional levels of molecules （LMP7, UBP, MHC-I, calreticulin） associated with endogenous antigen processing and presentation by using real-time fluorescent quantitative PCR （real-time FQ-PCR）. [Result] The results showed that the level of LMP7 mR- NAs was reduced significantly on the 3DPI （P〈0.05）; the level of UBP mRNAs was consistently up-regulated, which increased significantly on the 21DPI and 35DPI （P〈 0.05）; the level of MHC-I mRNAs was significantly down-regulated on the 7DPI （P〈 0.05）; the level of calreticulin mRNAs was up-regulated slightly without significant dif- ference. [Conclusion] PCV2 can inhibit the endogenous antigen processing and presentation ability of porcine skin-derived DCs at early stages of infection.

Dysfunction of peripheral blood dendritic cells from patients with chronic hepatitis B virus infection

AIM: To identify the property of dendritic cells (DCs) of peripheral blood monocytes (PBMC) in patients with chronic HBV infection. METHODS: Twenty patients with persistent HBV infection were included in this study, 10 healthy subjects being used as a control group. The peripheral blood mononuclear cells (PBMC) of T cell-depleted populations were incubated and induced into mature dendritic cells in the RPMI-1640 medium in the presence of cytokines GM-CSF, IL-4, FLt-3,TNF-alpha and 100mL.L(-1 )of fetal calf serum for a total of 10-12 days. The expressions of surface markers on DCs were evaluated using flow cytometric analysis. ELISA method was used to determine the cytokine levels of interleukin-12 (IL-12) and IL-10 in the supernatant produced by DCs. For detection of the stimulatory capacity of DCs to T cell proliferation, mytomycin C-treated DC were incubated with allogenic T cells. RESULTS: A typical morphology of mature DCs from healthy subjects and HBV-infected patients was induced in in vitro incubation, but the proliferation ability and cellular number of DCs from HBV-infected patients significantly decreased compared with healthy individuals. In particular, the expression levels of HLA-DR, CD80 (B7-1) and CD86 (B7-2) on DC surface from patients were also lower than that from healthy individuals (0.46 vs 0.92 for HLA-DR, 0.44 vs 0.88 for CD80 and 0.44 vs 0.84 for CD86,P【0.05). The stimulatory capacity and production of IL-12 of DCs from patients in allogenic mixed lymphocyte reaction (AMLR) significantly decreased, but the production level of nitric oxide (NO) by DCs simultaneously increased compared with healthy subjects (86 +/- 15 vs 170 +/- 22 micromol.L(-1), P 【0.05). CONCLUSION: The patients with chronic HBV infection have the defective function and immature phenotype of dendritic cells, which may be associated with the inability of efficient presentation of HBV antigens to host immune system for the clearance of HBV.

An effective vaccine against colon cancer in mice:Use of recombinant adenovirus interleukin-12 transduced dendritic cells

AIM： To investigate the effect of a vaccine with recombinant adenovirus interleukin-12 （AdVIL-12） transduced dendritic cells （DCs） against colon cancer in mice. METHODS： DCs and AdVIL-12 were incubated together at different time intervals and at different doses. Supernatant was collected and tested for IL-12 by enzyme-linked immunosorbent assay （ELISA）. In order to determine whether tumor cell lysate-pulsed （TP） AdVIL-12/DCs enhance therapeutic potential in the established tumor model, CT26 colon tumor cells were implanted subcutaneously （s.c.） in the midflank of naive BALB/c mice. Tumor-bearing mice were injected with a vaccination of CT26 TP AdVIL-12/DCs on d 3 and 10. As a protective colon tumor model, naive BALB/c mice were immunized s.c. in their abdomens with CT26 TP AdVIL-12/DCs twice at seven day intervals. After the immunization on d 7, the mice were challenged with a lethal dose of CT26 tumor cells and survival times were evaluated. Subsequently, cytotoxic T lymphocyte （CTL） activity and interferon gamma （IFNy） secretion was evaluated in the immunized mice, and assayed CTL ex vivo. RESULTS： Murine DCs were retrovirally transduced with AdVIL-12 efficiency, and the AdVIL-12 transduced DCs secreted a high level of IL-12 （AdVIL-12/DCs, 615.27 ± 42.3 pg/mL vs DCs, 46.32 ± 7.29 pg/mL, P 〈 0.05）. Vaccination with CT26 TP AdVIL-12/DCs could enhance anti-tumor immunity against CT26 colon tumor in murine therapeutic models （tumor volume on d 19：CT26 TP AdVIL-12/DCs 107 ± 42 mm^3 vs CT26 TP DCs 383± 65 mm^3, P 〈 0.05） and protective models. Moreover, the CT26 TP AdVIL-12/DC vaccination enhances tumor-specific CTL activity, producing high levels of IFN7 in immunized mice. Ex vivo primed T cells with AdVIL-12/DCs were able to induce more effective CTL activity than in primed T cells with CT26 TP/DCs （E：T = 100：1, 69.49% ± 6.11% specific lysis vs 37.44% ＋ 4.32% specific lysis, P 〈 0.05）.CONCLUSION： Vaccination with recombinant AdVIL-12 transduced DC pulsed tumor cell lysate enhance antitumor immunity specific to colon cancer in mice.

Probiotic Bio-Three induces Th1 and anti-inflammatory effects in PBMC and dendritic cells

AIM:To investigate the immune response of peripheral blood mononuclear cells(PBMCs)and dendritic cells (DCs)that were stimulated by probiotic preparations. METHODS:PBMCs were isolated,cultured,and stimulated with Bio-Three(a mixture of Bacillus mesentericus, Clostridium butyricum and Enterococcus faecalis;105, 10 6 and 10 7 CFU/mL for 24 h).Cytokine production of (1)circulating PBMCs;(2)PBMCs stimulated by probiotic preparation;(3)monocyte-derived DCs;and(4)DC andT cell co-culture was determined by enzyme-linked immunosorbent assay.Phenotypic analysis of circulating PBMCs was also investigated by flow cytometry.Blood was obtained from individuals who consumed Bio-Three (10 9 CFU/d B.mesentericus,C.butyricum and E.faecalis) for 2 wk,or those who did not take probiotics orally. RESULTS:In culture supernatants,interferon-γ(IFN-γ) and interleukin(IL)-10 production increased,but IL-4 and tumor necrosis factor-α(TNF-α)production by PBMCs decreased after 1 and 2 wk of probiotic treatment.Flow cytometry was also performed on day 14 and detected enhanced expression of CD11b,HLA-DR, CD4,CD45RA,CD25,CD44 and CD69 in response to Bio-Three.Furthermore,IL-10 and IL-12 were upregulated in supernatants of monocyte-derived DCs,and IFN-γand IL-10 were enhanced in supernatants of CD4 + T cells co-cultured with DCs. CONCLUSION:Bio-Three appeared to stimulate the Th1 immune response,downregulate pro-inflammatory cytokines(TNF-α)and upregulate anti-inflammatory cytokine(IL-10).Probiotics could be effective in activation of PBMCs and DCs.

Effect of a cancer vaccine prepared by fusions of hepatocarcinoma cells with dendritic cells

AIM: To prepare a cancer vaccine (H(22)-DC) expressing high levels of costimulatory molecules based on fusions of hepatocarcinoma cells (H(22)) with dendritic cells (DC) of mice and to analyze the biological characteristics and induction of specific CTL activity of H(22)-DC. METHODS: DCs were isolated from murine spleen by metrizamide density gradient centrifugation, purified based on its characteristics of semi-adhesion to culture plates and FcR-,and were cultured in the medium containing GM-CSF and IL-4. A large number of DC were harvested. DCs were then fused with H(22) cells by PEG and the fusion cells were marked with CD11c MicroBeads. The H(22)-DC was sorted with Mimi MACS sorter. The techniques of cell culture, immunocytochemistry and light microscopy were also used to test the characteristics of growth and morphology of H(22)-DC in vitro. As the immunogen, H(22)-DC was inoculated subcutaneously into the right armpit of BALB/C mice, and their tumorigenicity in vivo was observed. MTT was used to test the CTL activity of murine spleen in vivo. RESULTS: DC cells isolated and generated were CD11c+ cells with irregular shape, and highly expressed CD80, CD86 and CD54 molecules. H22 cells were CD11c- cells with spherical shape and bigger volume, and did not express CD80, CD86 and CD54 molecules.H(22)-DC was CD11c+ cells with bigger volume, being spherical, flat or irregular in shape, and highly expressed CD80, CD86 and CD54 molecules, too. H(22)-DC was able to divide and proliferate in vitro, but its activity of proliferation was significantly decreased as compared with H(22) cells and its growth curve was flatter than H(22) cells. After subcutaneous inoculation over 60 days, H(22)-DC showed no tumorigenecity in mice, which was significantly different from control groups (P【0.01). The spleen CTL activity against H(22) cells in mice implanted with fresh H(22)-DC was significantly higher than control groups (P 【 0.01). CONCLUSION: H(22)-DC could significantly stimulate the specific CTL activity of murine spleen, which suggests that the fusion cells have already obtained the function of antigen presenting of parental DC and could present H(22)specific antigen which has not been identified yet, and H(22)-DC could induce antitumor immune response; although simply mixed H(22) cells with DC could stimulate the specific CTL activity which could inhibit the growth of tumor in some degree, it could not prevent the generation of tumor. It shows that the DC vaccine is likely to become a helpful approach in immunotherapy of hepatocarcinoma.

Intestinal antigen-presenting cells in mucosal immune homeostasis:Crosstalk between dendritic cells,macrophages and B-cells

The intestinal immune system maintains a delicate balance between immunogenicity against invading pathogens and tolerance of the commensal microbiota. Inflammatory bowel disease (IBD) involves a breakdown in tolerance towards the microbiota. Dendritic cells (DC), macrophages (MΦ) and B-cells are known as professional antigen-presenting cells (APC) due to their specialization in presenting processed antigen to T-cells, and in turn shaping types of T-cell responses generated. Intestinal DC are migratory cells, unique in their ability to generate primary T-cell responses in mesenteric lymph nodes or Peyer’s patches, whilst MΦ and B-cells contribute to polarization and differentiation of secondary T-cell responses in the gut lamina propria. The antigen-sampling function of gut DC and MΦ enables them to sample bacterial antigens from the gut lumen to determine types of T-cell responses generated. The primary function of intestinal B-cells involves their secretion of large amounts of immunoglobulin A, which in turn contributes to epithelial barrier function and limits immune responses towards to microbiota. Here, we review the role of all three types of APC in intestinal immunity, both in the steady state and in inflammation, and how these cells interact with one another, as well as with the intestinal microenvironment, to shape mucosal immune responses. We describe mechanisms of maintaining intestinal immune tolerance in the steady state but also inappropriate responses of APC to components of the gut microbiota that contribute to pathology in IBD.

Bone marrow-derived dendritic cells pulsed with tumor lysates induce anti-tumor immunity against gastric cancer ex vivo

AIM： To investigate whether bone marrow-derived denritic cells pulsed with tumor lysates induce immunity against gastric cancer ex vivo. METHODS： c-kit＋ hematopoietic progenitor cells were magnetically isolated with a MiniMACS separator from BALB/c mice bone marrow cells. These cells were cultured with cytokines GM-CSF, IL-4, and TNFα to induce their maturation. They were analysed by morphological observation, phenotype analysis, and mixed lymphocyte reaction （MLR）. Bone marrowderived DCs （BM-DCs） were pulsed with tumor cell lysate obtained by rapid freezing and thawing at a 1：3 DC：tumor cell ratio. Finally, cytotoxic T lymphocyte （CTL） activity and interferon gamma （IFNγ） secretion was evaluated ex vivo. RESULTS： c-kit^＋ hematopoietic progenitor cells from mice bone marrow cells cultured with cytokines for 8 d showed the character of typical mature DCs.Morphologically, observed by light microscope, these cells were large with oval or irregularly shaped nuclei and with many small dendrites. Phenotypically, FACS analysis showed that they expressed.high levels of la, DEC-205, CD11b, CD80 and CD86 antigen, moderate levels of CD40, and negative for F4/80. Functionally, these cells gained the capacity to stimulate allogeneic T cells in MLR assay. However, immature DCs cultured with cytokines for 5 d did not have typical DCs phenotypic markers and could not stimulate allogeneic T cells. Ex vivo primed T cells with SGC-7901 tumor cell lysate-pulsed （TP） DCs were able to induce effective CTL activity against SGC-7901 tumor cells （E：T = 100：1, 69.55% ± 6.05% specific lysis）, but not B16 tumor cells, and produced higher levels of IFNγ, when stimulated with SGC-7901 tumor cells but not when stimulated with B16 tumor cells （1575.31 ± 60.25 pg/mL in SGC-7901 group vs 164.11± 18.52 pg/mL in B16 group, P 〈 0.01）. CONCLUSION： BM-derived DCs pulsed with tumor lysates Can induce anti-tumor immunity specific to gastric cancer ex vivo.

IRF family proteins and type I interferon induction in dendritic cells

Dendritic cells （DC）, although a minor population in hematopoietic cells, produce type I interferons （IFN） and other cytokines and are essential for innate immunity. They are also potent antigen presenters and regulate adaptive immunity. Among DC subtypes plasmacytoid DC （pDC） produce the highest amounts of type I IFN. In addition, pro- and anti-inflammatory cytokines such as IL-12 and IL-10 are induced in DC in response to Toll like receptor （TLR） signaling and upon viral infection. Proteins in the IRF family control many aspects of DC activity. IRF-8 and IRF-4 are essential for DC development. They differentially control the development of four DC subsets. IRF-8^-/- mice are largely devoid of pDC and CD8α^＋ DC, while IRF-4^-/- mice lack CD4^＋ DC. IRF-8^-/-, IRF4^-/-, double knock-out mice have only few CD8α CD4^-DC that lack MHC Ⅱ. IRF proteins also control type Ⅰ IFN induction in DC. IRF-7, activated upon TLR signaling is required for IFN induction not only in pDC, but also in conventional DC （cDC） and non-DC cell types. IRF-3, although contributes to IFN induction in fibroblasts, is dispensable in IFN induction in DC. Our recent evidence reveals that type Ⅰ IFN induction in DC is critically dependent on IRF-8, which acts in the feedback phase of IFN gene induction in DC. Type Ⅰ IFN induction in pDC is mediated by MyD88 dependent signaling pathway, and differs from pathways employed in other cells, which mostly rely on TLR3 and RIG-Ⅰ family proteins. Other pro-inflammatory cytokines are produced in an IRF-5 dependent manner. However, IRF-5 is not required for IFN induction, suggesting the presence of separate mechanisms for induction of type Ⅰ IFN and other pro-inflammatory cytokines. IFN and other cytokines produced by activated DC in turn advance DC maturation and change the phenotype and function of DC. These processes are also likely to be governed by IRF family proteins.

Role of adhesion molecules and dendritic cells in rat hepatic/renal ischemia-reperfusion injury and anti-adhesive intervention with anti-P-selectin lectin-EGF domain monoclonal antibody

AIM: To investigate the role of P-selectin, intercellular adhesion molecule-1 (ICAM-1) and dendritic cells (DCs)in liver/kidney of rats with hepatic/renal ischemiareperfusion injury and the preventive effect of anti-Pselectin lectin-EGF domain monoclonal antibody (anti-PsLEGFmAb) on the injury.METHODS: Rat models of hepatic and renal ischemiareperfusion were established. The rats were then divided into two groups, one group treated with anti-PsL-EGFmAb(n = 20) and control treated with saline (n = 20). Both groups were subdivided into four groups according to reperfusion time (1, 3, 6 and 24 h). The sham-operated group (n = 5) served as a control group. DCs were observed by the microscopic image method, while P-selectin and ICAM-1 were analyzed by immunohistochemistry.RESULTS: P-selectin increased significantly in hepatic sinusoidal endothelial cells and renal tubular epithelial cells 1 h after ischemia-reperfusion, and the expression of ICAM-1 was up-regulated in hepatic sinusoid and renal vessels after 6 h. CD1a+CD80+DCs gradually increased in hepatic sinusoidal endothelium and renal tubules and interstitium 1 h after ischemia-reperfusion, and there was the most number of DCs in 24-h group. The localization of DCs was associated with rat hepatic/renal function.These changes became less significant in rats treated with anti-PsL-EGFmAb.CONCLUSION: DCs play an important role in immune pathogenesis of hepatic/renal ischemia-reperfusion injury.Anti-PsL-EGFmAb may regulate and inhibit local DC immigration and accumulation in liver/kidney.

Probiotic modulation of dendritic cells co-cultured with intestinal epithelial cells

AIM： To investigate cytokine production and cell surface phenotypes of dendritic cells （DC） in the presence of epithelial cells stimulated by probiotics.METHODS： Mouse DC were cultured alone or together with mouse epithelial cell monolayers in normal or in- verted systems and were stimulated with heat-killed probiotic bacteria, Bifidobacterium lactis ADO 11 （BL）, Bifidobacterium bilfidum BGN4 （BB）, Lactobacillus casei IBS041 （LC）, and Lactobacillus acidophilus AD031 （LA）, for 12 h. Cytokine levels in the culture supernatants were determined by enzyme-linked immunosorbent as say and phenotypic analysis of DC was investigated by flow cytometry.RESULTS： BB and LC in singlecultured DC increased the expression of I-Ad, CD86 and CD40 （I-Ad, 18.51 vs 30.88, 46.11, CD86, 62.74 vs 92.7, 104.12; CD40, 0.67 vs 6.39, 3.37, P 〈 0.05）. All of the experimental probiot-ics increased the production of inflammatory cytokines, interleukin （IL）-6 and tumor necrosis factor （TNF）-α. However, in the normal coculture systems, LC and LA decreased the expression of I-A^α （39.46 vs 30.32, 33.26, P 〈 0.05）, and none of the experimental probiotics increased the levels of IL-6 or TNF-α. In the inverted coculture systems, LC decreased the expression of CD40 （1.36 vs -2.27, P 〈 0.05）, and all of the experimental probiotics decreased the levels of IL-6. In addition, BL increased the production of IL-10 （103.8 vs 166.0, P 〈 0.05） and LC and LA increased transforming growth factor-13 secretion （235.9 vs 618.9, 607.6, P 〈 0.05）.CONCLUSION： These results suggest that specific pro- biotic strains exert differential immune modulation mediated by the interaction of dendritic cells and epithelial cells in the homeostasis of gastrointestinal tract.

Relationship between the Changes of VEGF Level and Dendritic Cells in Peripheral Blood of Patients with Hepatocellular Carcinoma after Transcatheter Arterial Chemoembolization

In order to investigate the relationship between the VEGF level and the counts of dendritic cells （DCs） in peripheral blood of patients with hepatocellular carcinoma （HCC） before and after transcatheter arterial chemoembolization （TACE）, the peripheral blood was obtained from 37 patients with HCC who treated by TACE. The blood was obtained on the day before TACE, the first day, the 7th day and the 15th day after TACE respectively. The counts of DCs were quantified by flow cytometry. The plasma VEGF level was measured by ELESA kit. It was shown after TACE, the counts of DCs in peripheral blood were decreased significantly （P〈0.05）, and the VEGF level in peripheral blood was increased significantly （P〈0.05）. The counts of DCs in peripheral blood had an inverse correlation with the plasma VEGF level （r=-0.57, P〈0.05） after TACE. It was concluded that in patients with HCC after TACE, the increased plasma VEGF level appeared to have the effect to suppress the maturation of DCs, which may contribute to reduction of the body＇s anti-tumor immunity effect, with a consequence of recur and metastasis of tumor.

Recognition of HBV antigens and HBV DNA by dendritic cells

BACKGROUND: Hepatitis B virus (HBV) is a hepatotropic, noncytopathic, DNA virus which can cause acute and chronic infection. Viral persistence is associated with a weak or absent specific immune responses to HBV, particularly the cellular immune response. Dendritic cells (DCs) are professional antigen-presenting cells with a unique T cell stimulatory aptitude that play a crucial role in the instruction of adaptive immune responses upon infection. An impaired function of DCs was suggested by recent studies to account for the T and B cell hyporesponsiveness in chronic HBV infection. This review summarizes recent insights into the recognition of HBV antigens by DCs. DATA SOURCES: Studies were identified by searching MEDLINE and/or PubMed for articles using the key words 'hepatitis B virus (HBV)', 'dendritic cells', 'C-type lectins', 'mannose receptor', 'toll-like receptor', and 'dendritic cell-specific intercellular-adhesion-molecule-3 grabbing nonintegrin (DC-SIGN)' up to December 2009. Additional papers were identified by a manual search of the references from the key articles. RESULTS: DCs play an important role in the progress of hepatitis B, especially in the recognition of HBV. There are three main ways of recognition of HBV antigens by DCs. First, HBV DNA can be recognized by DCs through toll-like receptor 9 (TLR9) which activates the NF-kappa B signal pathway and p38 MAPK to up-regulate the expression of interferon (IFN) regulatory factor 7 (IRF-7) in a manner independent of type I IFN signaling, resulting in secretion of type I IFN and inflammatory cytokines, and induction of DC maturation and the adaptive immune response. Second, HBc/HBeAg cannot be recognized by DCs, but DNA or ssRNA encapsulated within HBcAg can be internalized by DCs through TLRs. Third, HBsAg can be internalized by DCs through the mannose receptor, which lacks the ability to induce DC maturation without the assistance of DC-SIGN. Meanwhile, there is some cross-talk among the three mechanisms, which induces an effective anti-viral response or HBV persistence. CONCLUSIONS: On the basis of these recognition processes, methods have been used to enhance the efficacy of DC-based vaccine against HBV and have been useful in the clinical application of HBV vaccine therapy. But the interactions between HBV antigens/HBV DNA and DCs are not clear, and cross-talk between TLRs and various ligands makes HBV antigen recognition by DCs more complicated. More efforts should be made to define the mechanisms and develop effective vaccines and therapies. (Hepatobiliary Pancreat Dis Int 2010; 9:584-592)

Role of mucosal dendritic cells in inflammatory bowel disease

The gastrointestinal innate and adaptive immune system continuously faces the challenge of potent stimuli from the commensal microflora and food constituents. These local immune responses require a tight control, the outcome of which is in most cases the induction of tolerance. Local T cell immunity is an important compartment of the specif ic intestinal immune system. T cell reactivity is programmed during the initial stage of its activation by professional presenting cells. Mucosal dendritic cells (DCs) are assumed to play key roles in regulating immune responses in the antigen-rich gastrointestinal environment. Mucosal DCs are a heterogeneous population that can either initiate (innate and adaptive) immune responses, or control intestinal inflammation and maintain tolerance. Defects in this regulation are supposed to lead to the two major forms of inflammatory bowel disease (IBD), Crohn's disease (CD) and ulcerative colitis (UC). This review will discuss the emerging role of mucosal DCs in regulating intestinal inflammation and immune responses.

In vivo anti-tumor effect of hybrid vaccine of dendritic cells and esophageal carcinoma cells on esophageal carcinoma cell line 109 in mice with severe combined immune deficiency

AIM： To develop a fusion vaccine of esophageal carcinoma cells and dendritic cells （DC） and observe its protective and therapeutic effect against esophageal carcinoma cell line 109 （EC109）. METHODS： The fusion vaccine was produced by fusing traditional polyethyleneglycol （PEG）, inducing cytokine, sorting CD34＋ magnetic microbead marker and magnetic cell system （MACS）. The liver, spleen and lung were pathologically tested after injection of the fusion vaccine. To study the therapeutic and protective effect of the fusion vaccine against tumor EC109, mice were divided immune group and therapeutic group. The immune group was divided into P, E, D and ED subgroups, immunized by phosphate buffered solution （PBS）, inactivated EC109, DC and the fusion vaccine respectively, and attacked by EC109 cells. The tumor size, weight, latent period and mouse survival period were recorded and statistically analyzed. The therapeutic group was divided into four subgroups： P, inactivated EC109, D and ED subgroups, which were attacked by EC109 and then treated with PBS, inactivated EC109, DC, and EC109-DC respectively. Pathology and flow cytometry were also used to study the therapeutic effect of the fusion vaccine against EC109 cells.RESULTS： Flow cytometry showed that the expression of folate receptor （FR）, EC109 （C）, Des （D） in human nasopharyngeal carcinoma cell line （HNE1） （B） was 78.21%, 89.50%, and 0.18%, respectively. The fusion cells （C） were highly expressed. No tumor was found in the spleen, lung and liver after injection of the fusion vaccine. Human IgG was tested in peripheral blood lymphocytes （PBL）. In the immune group, the latent period was longer in EC109-DC subgroup than in other subgroups, while the tumor size and weight were also smaller than those in ED subgroup. In the therapeutic group, the tumor size and weight were smaller in ED subgroup than in P, inactivated EC109 and DC subgroups. CONCLUSION： Fusion cells are highly expressed not only in FR but also in CD80. The fusion vaccine has a distinctive protective effect against tumor EC109 and can inhibit the growth of tumor in mice, and its immune protection against tumor attack is more significant.

Effects of dendritic cells from cord blood CD34^+ cells on human hepatocarcinoma cell line BEL-7402 in vitro and in SCID mice

AIM: To develop a cancer vaccine of dendritic cells derived from human cord blood CD34+ cells and to investigate its cytotoxicity on human hepatocarcinoma cells in vitro and in sever combined immunodeficiency (SCID) mice. METHODS: Lymphocytes from cord blood or peripheral blood were primed by DCs, which were derived from cord blood and pulsed with whole tumor cell lysates. Nonradiative neutral red uptake assay was adopted to detect the cytotoxicity of primed lymphocytes on human hepatocartinoma cell line BEL-7402 in vitro. The anti-tumor effect of primed lymphocytes in vivo was detected in SCID mice, including therapeutic effect and vaccination effect. RESULTS: The cytotoxicity of DC vaccine primed lymphocytes from cord blood or peripheral blood on human hepatocarcinoma cell line BEL-7402 was significantly higher than that of unprimed lymphocytes in vitro (44.09% vs 14.69%, 47.92% vs 19.44%, P<0.01). There was no significant difference between the cytotoxicity of primed lymphocytes from cord blood and peripheral blood (P>0.05). The tumor growth rate and tumor size were smaller in SCID mice treated or vaccinated with primed lymphocytes than those with unprimed lymphocytes. SCID mice vaccinated with primed lymphocytes had a lower tumor incidence (80% vs 100%, P<0.05) and delayed tumor latent period compared with mice vaccinated with unprimed lymphocytes (11d vs 7 d,P<0.01). CONCLUSION: Vaccine of cord blood derived-DCs has an inhibitory activity on growth of human hepatocarcinoma cells in vitro and in SCID mice. The results also implicate the potential role of cord blood derived-DC vaccine in clinical tumor immunotherapy.

Uric acid enhances T cell immune responses to hepatitis B surface antigen-pulsed-dendritic cells in mice

AIM： To study the induction of T cellular immune responses in BALB/c mice immunized with uric acid and dendritic cells （DCs） pulsed with hepatitis B virus surface antigen （HBsAg）. METHODS： DCs were generated from bone-marrow cells of BABL/c mice, and then pulsed or unpulsed with HBsAg protein （HBsAg-pulsed-DCs or unpulsed-DCs） in vitro. BABL/c mice were immunized with HBsAg-pulsed- DCs （1 × 10^6） and uric acid, injected through the tail vein of each mouse. The mice in control groups were immunized with HBsAg-pulsed-DCs alone, unpulsed- DCs alone or 200 μg uric acid alone or PBS alone. The immunization was repeated 7 d later. Cytotoxic T lymphocytes （CTLs） in vivo were determined by the CFSE labeled spleen lysis assay. Spleen cells or spleen T cells were isolated, and re-stimulated in vitro with HBsAg for 120 h or 72 h. Production of IFN-γ, and IL-4 secreted by spleen cells were determined by ELISA method; proliferation of spleen T cells were detected by flow cytometry. RESULTS： The cytotoxicities of HBsAg-specific-CTLs, generated after immunization of HBsAg-pulsed-DCs and uric acid, were 68.63% ±11.32% and significantly stronger than that in the control groups （P 〈 0.01）. Compared with control groups, in mice treated with uric acid and HBsAg-pulsed-DCs, the spleen T cell proliferation to HBsAg re-stimulation was stronger （1.34 ± 0.093 vs 1.081±0.028, P 〈 0.01）, the level of IFN-t, secreted by splenocytes was higher （266.575 ± 51.323 vs 135.223 ±32.563, P 〈 0.01） , and IL-4 level wasower （22.385 ± 2.252 vs 40.598 ± 4.218, P 〈 0.01）. CONCLUSION： Uric acid can strongly enhance T cell immune responses induced by HBsAg-pulsed-DCs vaccine. Uric acid may serve as an effective adjuvant of DC vaccine against HBV infection.

HBsAg loading on dendritic cells in patients with chronic hepatitis B: expressions of phenotypic molecules

BACKGROUND: The antigen reducing ability of dentritic cells (DCs), a kind of antigen presenting cells (APCs) initiating immune response, is associated with the specific immune tolerance of chronic hepatitis B(CHB) patients. However, the dysfunction of DCs can be possibly reversed by the stimulation of antigen peptides. In this study, DCs were cultured from peripheral blood monocytes (PBMCs) in patients with CHB in vitro, and the expression of phenotypic molecules on DCs loaded by different concentrations of HBsAg was observed. METHODS: Forty patients with CHB were divided randomly into 4 groups(10 patients in each group). PBMCs were isolated, and DCs were cultured after addition of granulocyte/macrophage colony-stimulating factor (GMCSF) and interleukin 4(IL-4). On the 9th day, DCs of the experimental groups were loaded at HBsAg concentrations of 2.5mg/L, 5mg/L and 10mg/L for 24 hours, whereas those of the control group were not loaded. An electron microscope was used to analyze the morphological changes of the DCs. The expression of phenotypic molecules on DCs in different groups was detected with flow cytometry. RESULTS: A combination of GM-CSF and IL-4 produced DCs from PBMCs in patients with CHB after being cultured for 9 days, whose morphological changes were tested by an electron microscope. The expression of phenotypic molecules on DCs in the control group was as low as CD83 (8.02±3.99)%, CD80(8.77±2.06)%, and MHC-DR (14.05±2.66)%. Loaded by different concentrations of HBsAg, the up-regulation of phenotypic molecules on DCs was found, with CD83(18.35±2.93)%, CD80(42.63±7.15)% and MHC-DR(47.49±6.59)% in 2.5mg/L HBsAg loading group, CD83(17.88±3.12)%, CD80(45.24± 10.93)% and MHC-DR(47.07±8.52)% in 5mg/L HBsAg loading group and CD83(16.74±2.86)%, CD80(44.59±6.99)% and MHC-DR(48.59±7.42)% in 10mg/L HBsAg loading group, respectively. Compared with the control group, the phenotypic molecules in the experimental groups were all different significantly (P<0.01), but among them, there were no differences (P>0.05). CONCLUSIONS: DCs cultured from PBMCs in the patients with CHB under the conditions of GM-CSF and IL-4 present on the typical dendritic morphology but are immature for expressing low phenotypic molecules. Loaded by different concentrations of HBsAg, the immature DCs can differentiate to mature DCs for expressing increasing phenotypic molecules.