Meningeal lymphatic vessel crosstalk with central nervous system immune cells in aging and neurodegenerative diseases

Meningeal lymphatic vessels form a relationship between the nervous system and periphery, which is relevant in both health and disease. Meningeal lymphatic vessels not only play a key role in the drainage of brain metabolites but also contribute to antigen delivery and immune cell activation. The advent of novel genomic technologies has enabled rapid progress in the characterization of myeloid and lymphoid cells and their interactions with meningeal lymphatic vessels within the central nervous system. In this review, we provide an overview of the multifaceted roles of meningeal lymphatic vessels within the context of the central nervous system immune network, highlighting recent discoveries on the immunological niche provided by meningeal lymphatic vessels. Furthermore, we delve into the mechanisms of crosstalk between meningeal lymphatic vessels and immune cells in the central nervous system under both homeostatic conditions and neurodegenerative diseases, discussing how these interactions shape the pathological outcomes. Regulation of meningeal lymphatic vessel function and structure can influence lymphatic drainage, cerebrospinal fluid-borne immune modulators, and immune cell populations in aging and neurodegenerative disorders, thereby playing a key role in shaping meningeal and brain parenchyma immunity.

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.

Immunity of Unloaded Dendritic Cells in Lung Melanoma of Mice

In order to investigate the immunity of unloaded dendritic cells （DCs） derived from murine bone marrow to preexisting lung melanoma metastases of mice, MO5 were intravenously injected to induce lung metastases in syngeneic C57BI-/6 mice. Unloaded GM-CSF DCs, PBS and DCs＋SIINFEKEL were subcutaneously injected into the mice, which were divided as experimental group, negative control group and positive control group respectively. Monoclonal antibody was used to deplete NK or T cells separately. The immunity-inhibitory effects on the lung melanoma were observed and the corresponding effector cells were examined. It was found that in the experimental and positive groups, the regression was induced in metastatic nodules in the lungs of tumor-bearing mice, but abrogated by treatment with anti-asialo-GM1 but not anti-CD8. It was concluded that the unloaded DCs could suppress the lung melanoma metastases to some extent, which was mediated by NK cells, and could be used as a potent therapeutic agents for lung tumor.

Ethanol changes Nestin-promoter induced neural stem cells to disturb newborn dendritic spine remodeling in the hippocampus of mice

Adolescent binge drinking leads to long-lasting disorders of the adult central nervous system,particularly aberrant hippocampal neurogenesis.In this study,we applied in vivo fluorescent tracing using NestinCreERT2::Rosa26-tdTomato mice and analyzed the endogenous neurogenesis lineage progression of neural stem cells(NSCs)and dendritic spine formation of newborn neurons in the subgranular zone of the dentate gyrus.We found abnormal orientation of tamoxifen-induced tdTomato+(tdTom^(+))NSCs in adult mice 2 months after treatment with EtOH(5.0 g/kg,i.p.)for 7 consecutive days.EtOH markedly inhibited tdTom^(+)NSCs activation and hippocampal neurogenesis in mouse dentate gyrus from adolescence to adulthood.EtOH(100 mM)also significantly inhibited the proliferation to 39.2%and differentiation of primary NSCs in vitro.Adult mice exposed to EtOH also exhibited marked inhibitions in dendritic spine growth and newborn neuron maturation in the dentate gyrus,which was partially reversed by voluntary running or inhibition of the mammalian target of rapamycinenhancer of zeste homolog 2 pathway.In vivo tracing revealed that EtOH induced abnormal orientation of tdTom+NSCs and spatial misposition defects of newborn neurons,thus causing the disturbance of hippocampal neurogenesis and dendritic spine remodeling in mice.

Tumor-derived DEFB1 induces immune tolerance by inhibiting maturation of dendritic cell and impairing CD8+T cell function in esophageal squamous cell carcinoma

Objective:CD8+T cells are the key effector cells in the anti-tumor immune response.The mechanism underlying the infiltration of CD8+T cells in esophageal squamous cell carcinoma(ESCC)has not been clearly elucidated.Methods:Fresh ESCC tissues were collected and grouped according to the infiltration density of CD8+T cells.After the transcriptome sequencing on these samples and the combined analyses with The Cancer Genome Atlas(TCGA)ESCC data,a secreted protein DEFB1 was selected to explore its potential role in the infiltration of CD8+T cells.Bioinformatics analyses,histological verification and in vitro experiments were then performed.Results:DEFB1 was highly expressed in ESCC,and the high expression of DEFB1 was an independent risk factor for overall survival.Since the up-regulation or down-regulation of DEFB1 did not affect the proliferation,migration and apoptosis of ESCC cells,we speculated that the oncogenic effect of DEFB1 was achieved by regulating microenvironmental characteristics.Bioinformatics analyses suggested that DEFB1 might play a major role in the inflammatory response and anti-tumor immune response,and correlate to the infiltration of immature dendritic cell(imDC)in ESCC.Histological analyses further confirmed that there were less CD8+T cells infiltrated,less CD83+mature DC(mDC)infiltrated and more CD1a+imDC infiltrated in those ESCC samples with high expression of DEFB1.After the treatment with recombinant DEFB1 protein,the maturation of DC was hindered significantly,followed by the impairment of the killing effects of T cells in both 2D and 3D culture in vitro.Conclusions:Tumor-derived DEFB1 can inhibit the maturation of DC and weaken the function of CD8+T cells,accounting for the immune tolerance in ESCC.The role of DEFB1 in ESCC deserves further exploration.

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.

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.

Heat-shocked tumor cell lysate-pulsed dendritic cells induce effective anti-tumor immune response in vivo

AIM. To study whether heat-shocked tumor cells could enhance the effect of tumor cell lysate-pulsed dendritic cells （DCs） in evoking anti-tumor immune response in vivo. METHODS： Mouse undifferentiated colon cancer cells （CT-26） were heated at 42℃ for 1 h and then frozenthawed. The bone marrow-derived DCs pulsed with heatshocked CT-26 cell lysate （HSCT-26 DCs） were recruited to immunize syngeneic naive BALB/c mice. The cytotoxic activity of tumor specific cytotoxic T lymphocytes （CTLs） in mouse spleen was evaluated by IFN-enzyme-linked immunospot （ELISpot） and LDH release assay. The immunoprophylactic effects induced by HSCT-26 DCs in mouse colon cancer model were compared to those induced by single CT-26 cell lysate-pulsed DCs （CT-26 DCs） on tumor volume, peritoneal metastasis and survival time of the mice. RESULTS： Heat-treated CT-26 cells showed a higher hsp70 protein expression. Heat-shocked CT-26 cell lysate pulsing elevated the co-stimulatory and MHC-Ⅱ molecule expression of bone marrow-derived DCs as well as interleukin-12 p70 secretion. The IFN-y secreting CTLs induced by HSCT-26 DCs were significantly more than those induced by CT-26 DCs （P=0.002）. The former CTLs＇ specific cytotoxic activity was higher than the latter CTLs＇ at a serial E/T ratio of 10：1, 20：1, and 40：1. Mouse colon cancer model showed that the tumor volume of HSCT-26 DC vaccination group was smaller than that of CT-26 DC vaccination group on tumor volume though there was no statistical difference between them （24 mm^3 vs 8 mm^3, P=0.480）. The median survival time of mice immunized with HSCT-26 DCs was longer than that of those immunized with CT-26 DCs （57 d vs 43 d, P = 0.0384）. CONCLUSION： Heat-shocked tumor cell lysate-pulsed DCs can evoke anti-tumor immune response in vivo effectively and serve as a novel DC-based tumor vaccine.

Immunotherapy with dendritic cells and cytokine-induced killer cells for hepatocellular carcinoma: A meta-analysis

BACKGROUND Hepatocellular carcinoma(HCC) has been revealed as the second most common cause of cancer-related deaths worldwide. The introduction of cell-based immunotherapy, including dendritic cells(DCs) and cytokine-induced killer cells(CIKs), has brought HCC patients an effective benefit. However, the efficacy and necessity of cellular immunotherapy after different interventional therapy remains to be further explored.AIM To investigate the efficacy of cellular immunotherapy, involving DCs and CIKs,combined with different conventional treatments of HCC.METHODS We performed a literature search on PubMed and Web of Science up to February15, 2019. Long-term efficacy(overall survival and recurrence) and short-term adverse effects were investigated to assess the effectiveness of immunotherapy with DCs and/or CIKs. Review Manager 5.3 was used to perform the analysis.RESULTS A total of 22 studies involving 3756 patients selected by eligibility inclusion criteria were forwarded for meta-analysis. Combined with the conventional clinical treatment, immunotherapy with DCs and/or CIKs was demonstrated to significantly improve overall survival at 6 mo [risk ratio(RR) = 1.07;95%confidence interval(CI): 1.01-1.13, P = 0.02], 1 year(RR = 1.12;95%CI: 1.07-1.17, P< 0.00001), 3 years(RR = 1.23;95%CI: 1.15-1.31, P < 0.00001) and 5 years(RR =1.26;95%CI: 1.15-1.37, P < 0.00001). Recurrence rate was significantly reduced by cellular immunotherapy at 6 mo(RR = 0.50;95%CI: 0.36-0.69, P < 0.0001) and 1 year(RR = 0.82;95%CI: 0.75-0.89, P < 0.00001). Adverse effect assessment addressed that immunotherapy with DCs and/or CIKs was accepted as a safe,feasible treatment.CONCLUSION Combination immunotherapy with DCs, CIKs and DC/CIK with various routine treatments for HCC was evidently suggested to improve patients’ prognosis by increasing overall survival and reducing cancer recurrence.

Hepatocellular carcinoma-specific immunotherapy with synthesized α1,3-galactosyl epitope-ulsed dendritic cells and cytokine-induced killer cells

AIM： To evaluate the safety and clinical efficacy of a new immunotherapy using both α-Gal epitope-pulsed dendritic cells （DCs） and cytokine-induced killer cells. METHODS： Freshly collected hepatocellular carcinoma （HCC） tumor tissues were incubated with a mixture of neuraminidase and recombinant αl,3-galactosyltrans- ferase （αI,3GT） to synthesize α-Gal epitopes on car- bohydrate chains of the glycoproteins of tumor mem- branes. The subsequent incubation of the processed membranes in the presence of human natural anti-Gal IgG resulted in the effective phagocytosis to the tumor membrane by DCs. Eighteen patients aged 38-78 years with stage 111 primary HCC were randomly chosen for the study; 9 patients served as controls, and 9 patients were enrolled in the study group.RESULTS： The evaluation demonstrated that the pro- cedure was safe; no serious side effects or autoimmune diseases were observed. The therapy significantly pro- longed the survival of treated patients as compared with the controls （17.1 ± 2.01 mo vs 10.1 ±4.5 mo, P = 0.00121）. After treatment, all patients in the study group had positive delayed hypersensitivity and robust systemic cytotoxicity in response to tumor lysate as measured by interferon-y-expression in peripheral blood mononuclear cells using enzyme-linked immunosorbent spot assay. They also displayed increased numbers of CD8-, CD45RO- and CD56-positive cells in the peripheral blood and decreased α-fetoprotein level in the se- rum. CONCLUSION： This new tumor-specific immunotherapy is safe, effective and has a great potential for the treat- ment of tumors.

Mechanism of immune tolerance induced by donor derived immature dendritic cells in rat high-risk corneal transplantation

·AIM: To study the role of immature dendritic cells (imDCs) on immune tolerance in rat penetrating keratoplasty (PKP) in high -risk eyes and to investigate the mechanism of immune hyporesponsiveness induced by donor-derived imDCs. ·METHODS: Seventy-five SD rats (recipient) and 39 Wistar rats (donor) were randomly divided into 3 groups: control, imDC and mature dendritic cell (mDC) group respectively. Using a model of orthotopic corneal transplantation in which allografts were placed in neovascularized high -risk eyes of recipient rat. Corneal neovascularization was induced by alkaline burn in the central cornea of recipient rat. Recipients in imDC group or mDC group were injected donor bone marrow-derived imDCs or mDCs of 1 ×10 6 respectively 1 week before corneal transplantation tail vein. Control rat received the same volume of PBS. In each group, 16 recipients were kept for determination of survival time and other 9 recipients were executed on day 3, 7 and 14 after transplantation. Cornea was harvested for hematoxylin eosin staining and acute rejection evaluation, Western blot was used to detect the expression level of Foxp3. ·RESULTS: The mean survival time of imDC group was significantly longer than that of control and mDC groups (all 【0.05). The expression level of Foxp3 on CD4 + CD25 + T cells of imDC group (2.24 ±0.18) was significantly higher than that in the control (1.68 ±0.09) and mDC groups (1.46±0.13) (all 【0.05).·CONCLUSION: Donor -derived imDC is an effective treatment in inducing immune hyporesponsiveness in rat PKP. The mechanism of immune tolerance induced by imDC might be inhibit T lymphocytes responsiveness by regulatory T cells. ·

Antitumor immunity by a dendritic cell vaccine encoding secondary lymphoid chemokine and tumor lysate on murine prostate cancer

Aim： To investigate the antitumor immunity by a dendritic cell （DC） vaccine encoding secondary lymphoid chemokine gene and tumor lysate on murine prostate cancer. Methods： DC from bone marrow of C57BL/6 were transfected with a plasmid vector expressing secondary lymphoid chemokine （SLC） cDNA by Lipofectamine2000 liposome and tumor lysate. Total RNA extracted from SLC＋lysate-DC was used to verify the expression of SLC by reverse transcriptase-polymerase chain reaction （RT-PCR）. The immunotherapeutic effect of DC vaccine on murine prostate cancer was assessed. Results： We found that in the prostate tumor model of C57BL/6 mice, the adminstration of SLC＋lysate-DC inhibited tumor growth most significantly when compared with SLC-DC, lysate-DC, DC or phos- phate buffer solution （PBS） counterparts （P 〈 0.01）. Immunohistochemical fluorescent staining analysis showed the infiltration of more CD4＋, CD8＋ T cell and CD11c＋ DC within established tumor treated by SLC＋lysate-DC vaccine than other DC vaccines （P 〈 0.01）. Conclusion： DC vaccine encoding secondary lymphoid chemokine and tumor lysate can elicit significant antitumor immunity by infiltration of CD4＋, CD8＋ T cell and DC, which might provide a potential immunotherapy method for prostate cancer.

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.

Immune responses of dendritic cells combined with tumor-derived autophagosome vaccine on hepatocellular carcinoma

Background： To induce and collect tumor-derived autophagosomes （DRibbles） from tumor cells as an antitumor vaccine by inhibiting the functions of proteasomes and lysosomes. Methods： Dendritic cells （DCs） generated from peripheral blood mononuclear cell （PBMC） of hepatocellular carcinoma （HCC） patients were cocultured with DRibbles, and then surface molecules of DCs, as well as surface molecules on DCs, were determined by flow cytometry. Meanwhile, immune responses of the DCs-DRibbles were examined by mixed lymphocyte reactions. Results： DRibbles significantly induced the expression of CD80, CD83, CD86 and HLA-DR on DCs. The enzyme-linked immunosorbnent assay （ELISA） showed that IFN-γ, levels after vaccination increased than before in most patients, but CDS＋ proportion of PBMC increased only in nine patients. Higher levels of IFN-γ, were detected in the CD8＋ cells than CD4＋ T cells. These results suggested that DCs-DRibbles vaccine could induce antigen-specific cellular immune response on HCC and could prime strong CD8＋ T cell responses, supporting it as a tumor vaccine candidate. Conclusions： Our results demonstrate that HCC/DRibbles-pulsed DCs immunotherapy might be deployed as an effective antitumor vaccine for HCC immunotherapy in clinical trials.

Vaccination with dendritic cells pulsed with hepatitis C pseudo particles induces specific immune responses in mice

AIM: To explore dendritic cells (DCs) multiple functions in immune modulation. METHODS: We used bone-marrow derived dendritic cells from BALB/c mice pulsed with pseudo particles from the hepatitis C virus to vaccinate naive BALB/c mice. Hepatitis C virus (HCV) pseudo particles consist of the genotype 1b derived envelope proteins E1 and E2, covering a non-HCV core structure. Thus, not a single epitope, but the whole "viral surface" induces immunogenicity. For vaccination, mature and activated DC were injected subcutaneously twice. RESULTS: Humoral and cellular immune responses measured by enzyme-linked immunosorbent assay and interferon-gamma enzyme-linked immunosorbent spot test showed antibody production as well as T-cellsdirected against HCV. Furthermore, T-cell responses confi rmed two highly immunogenic regions in E1 and E2 outside the hypervariable region 1. CONCLUSION: Our results indicate dendritic cells as a promising vaccination model for HCV infection that should be evaluated further.

Clinical and Pathological Implications of Increases in Tonsillar CD19+CD5+B Cells,CD208+Dendritic Cells,and IgA1-positive Cells of Immunoglobulin A Nephropathy

Objective:Several studies indicated that tonsillectomy can improve the prognosis of patients with immunoglobulin A nephropathy(IgAN).However,the relationship between tonsillar immunity and IgAN is still unclear.Methods:A total of 14 IgAN patients were recruited in the current study from May 2015 to April 2016 in Tongji Hospital.B cells,dendritic cells(DCs),and IgAl positive cells in human tonsils were detected using immunofluorescence and immunohistochemistry.Correlations between these cells and clinicopathologic features were evaluated.

Enhancing Antitumor by Immunization with Fusion of Dendritic Cells and Engineered Tumor Cells

A novel approach for a dentritic cells (DCs) based tumor vaccine was developed for the formation of hybrid engineered J558 after fusion with DCs. To make the hybrid tumor vaccine generate more efficient specific CTL cytotoxicity against wild type tumor cells, we genetically engineered tumor cells with mIL 12 gene prior to the cell fusion. mIL 12 was detected at 870±60 pg/(10 5 cells/ml) in the culture supernatants and the fusion ratio was about 30 % by the co focal microscopic analysis. Vaccination of mice with DCs fused with engineered J558 induced more efficient tumor specific CTL cytotoxicity against wild type tumor cells in vitro and with efficient antitumor immunity in vivo . These results suggest that this approach of using DCs fused with engineered tumor cells could be applied in clinical settings of DCs based cancer vaccines.

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.

Emerging roles of plasmacytoid dendritic cell crosstalk in tumor immunity

Plasmacytoid dendritic cells(pDCs)are a pioneer cell type that produces type I interferon(IFN-I)and promotes antiviral immune responses.However,they are tolerogenic and,when recruited to the tumor microenvironment(TME),play complex roles that have long been a research focus.The interactions between p DCs and other components of the TME,whether direct or indirect,can either promote or hinder tumor development;consequently,p DCs are an intriguing target for therapeutic intervention.This review provides a comprehensive overview of p DC crosstalk in the TME,including crosstalk with various cell types,biochemical factors,and microorganisms.An in-depth understanding of p DC crosstalk in TME should facilitate the development of novel p DC-based therapeutic methods.