Dendritic Cell IL-12 Research Articles

Mycobacterium bovis and BCG induce different patterns of cytokine and chemokine production in dendritic cells and differentiation patterns in CD4+ T cells

Mycobacterium tuberculosis can infect dendritic cells (DCs), but the molecular mechanism by which these cells contribute to tuberculosis pathogenesis is largely unclear. Using Mycobacterium bovis and the attenuated strain M. bovis BCG as model strains, we analysed cytokine and chemokine secretion in murine DCs infected with M. bovis and BCG at 6, 12 and 24 h post-infection. BCG enhanced production of MCP-1, RANTES, IL-12, TNF-α and IL-6 in DCs, while M. bovis promoted secretion of IL-1β, IL-10 and IL-23. Heat-killed BCG and M. bovis both stimulated cytokine production, but at significantly lower concentrations than corresponding live bacteria. Quantitative RT-PCR and Western blotting indicated that NF-κB regulates production of most cytokines and chemokines. After DCs were infected for 24 h, the culture was used to activate naïve CD4(+) T cells. A combination of the supernatant and activated DCs infected with M. bovis gave high expression of foxp3 and IL-10, directing differentiation of naïve CD4(+) T cells into regulatory T cells (CD4(+)CD25(+)Foxp3(+)) more effectively than BCG. Furthermore, M. bovis-infected DC cultures induced CD4(+) T cells to express significantly higher levels of IL-17, a Th17-type cytokine, while BCG-infected DC cultures stimulated an apparently higher production of IFN-γ, a Th1-type cytokine. In addition, the mycobacteria did not exert a direct effect on the differentiation of CD4(+) T cells. These differential cytokine profiles in DCs and CD4(+) T cells, and the resultant development of CD4(+) T subsets, may be related to the pathogenesis of tuberculosis.

PD-L2 modulates asthma severity by directly decreasing dendritic cell IL-12 production.

Studies examining the role of PD-L2/PD-1 in asthma have yielded conflicting results. To clarify its role, we examined PD-L2 expression in biopsies from human asthmatics and lungs of aeroallergen-treated mice. PD-L2 expression in bronchial biopsies correlated with the severity of asthma. In mice, allergen exposure increased PD-L2 expression on pulmonary myeloid dendritic cells, and PD-L2 blockade diminished allergen-induced airway hyperresponsiveness (AHR). In contrast, PD-1 blockade had no impact, suggesting that PD-L2 promotes AHR in a PD-1-independent manner. Decreased AHR was associated with enhanced serum IL-12 p40 and in vitro stimulation of DCs with allergen and PD-L2-Fc reduced IL-12 p70 production, suggesting that PD-L2 inhibits allergen-driven IL-12 production. In our model, IL-12 did not diminish Th2 responses, but rather directly antagonized IL-13-inducible gene expression, highlighting a novel role for IL-12 in regulation of IL-13 signaling. Thus, allergen-driven enhancement of PD-L2 signaling through a PD-1-independent mechanism limits IL-12 secretion, exacerbating AHR.

Butyrate increases IL-23 production by stimulated dendritic cells

The gut microbiota is essential for the maintenance of intestinal immune homeostasis and is responsible for breaking down dietary fiber into short-chain fatty acids (SCFAs). Butyrate, the most abundant bioactive SCFA in the gut, is a histone deacetylase inhibitor (HDACi), a class of drug that has potent immunomodulatory properties. This characteristic of butyrate, along with our previous discovery that conventional dendritic cells (DCs) are required for the development of experimental colitis, led us to speculate that butyrate may modulate DC function to regulate gut mucosal homeostasis. We found that butyrate, in addition to suppressing LPS-induced bone marrow-derived DC maturation and inhibiting DC IL-12 production, significantly induced IL-23 expression. The upregulation of mRNA subunit IL-23p19 at the pretranslational level was consistent with the role of HDACi on the epigenetic modification of gene expression. Furthermore, the mechanism of IL-23p19 upregulation was independent of Stat3 and ZBP89. Coculture of splenocytes with LPS-stimulated DCs pretreated with or without butyrate was performed and showed a significant induction of IL-17 and IL-10. We demonstrated further the effect of butyrate in vivo using dextran sulfate sodium (DSS)-induced colitis and found that the addition of butyrate in the drinking water of mice worsened DSS-colitis. This is in contrast to the daily intraperitoneal butyrate injection of DSS-treated mice, which mildly improved disease severity. Our study highlights a novel effect of butyrate in upregulating IL-23 production of activated DCs and demonstrates a difference in the host response to the oral vs. systemic route of butyrate administration.

Protective Role for TLR4 Signaling in Atherosclerosis Progression as Revealed by Infection with a Common Oral Pathogen

Clinical and epidemiological studies have implicated chronic infections in the development of atherosclerosis. It has been proposed that common mechanisms of signaling via TLRs link stimulation by multiple pathogens to atherosclerosis. However, how pathogen-specific stimulation of TLR4 contributes to atherosclerosis progression remains poorly understood. In this study, atherosclerosis-prone apolipoprotein-E null (ApoE(-/-)) and TLR4-deficient (ApoE(-/-)TLR4(-/-)) mice were orally infected with the periodontal pathogen Porphyromonas gingivalis. ApoE(-/-)TLR4(-/-) mice were markedly more susceptible to atherosclerosis after oral infection with P. gingivalis. Using live animal imaging, we demonstrate that enhanced lesion progression occurs progressively and was increasingly evident with advancing age. Immunohistochemical analysis of lesions from ApoE(-/-)TLR4(-/-) mice revealed an increased inflammatory cell infiltrate composed primarily of macrophages and IL-17 effector T cells (Th17), a subset linked with chronic inflammation. Furthermore, enhanced atherosclerosis in TLR4-deficient mice was associated with impaired development of Th1 immunity and regulatory T cell infiltration. In vitro studies suggest that the mechanism of TLR4-mediated protective immunity may be orchestrated by dendritic cell IL-12 and IL-10, which are prototypic Th1 and regulatory T cell polarizing cytokines. We demonstrate an atheroprotective role for TLR4 in response to infection with the oral pathogen P. gingivalis. Our results point to a role for pathogen-specific TLR signaling in chronic inflammation and atherosclerosis.

Synergistical toll-like receptors activated dendritic cells induce antitumor effects against carcinoembryonic antigen-expressing colon cancer

Dendritic cell (DC)-based cancer vaccine represents a promising immunotherapy against cancer. There has been recent evidence which have suggested that toll-like receptor (TLR) ligands may be critical for DC preparation; this was usually omitted in the past. Our study is designed to investigate if the vaccination of synergistical toll-like receptors activated DCs can induce more potent cytotoxic T Lymphocytes (CTL) responses and antitumor activity in carcinoembryonic antigen (CEA) transgenic mouse tumor models. We involved combination of TLR3 and TLR7/8 ligands in culture protocol of DCs. The DCs' surface molecules expression, IL-12 secretion and proliferation capacity of lymphocytes were tested. We also investigate the CTL activity against MC38-CEA colon tumor cells and the prophylactic and therapeutic effects of DC vaccination in subcutaneous mouse colon tumor models. Compared with conventionally generated DCs, we showed synergistic TLR-activated DCs exhibited higher surface molecule expression, significantly higher secretion of IL-12 and more potent proliferating capacity of lymphocytes. Synergistic TLR-activated DCs were also able to induce lymphocytes possessing the specific cytotoxicity against MC38-CEA cells in vitro. Vaccination with CEA epitope pulsed TLR-activated DCs elicited antigen-specific preventive effect on MC38-CEA tumors, but failed to cure the tumor-bearing mice, that may be due to the suboptimal epitope selected and host immunosuppression. Our results have proved that combined activation of TLRs can lead to better maturation status of DCs and also induce more effective antitumor immune responses against colon cancer, suggesting this may be a potential strategy to develop more powerful DC cancer vaccines.

α-MSH-Stimulated Tolerogenic Dendritic Cells Induce Functional Regulatory T Cells and Ameliorate Ongoing Skin Inflammation

The neuropeptide α-melanocyte-stimulating hormone (α-MSH) is a well-known mediator of skin pigmentation. More recently, it has been shown that α-MSH also exerts a strong anti-inflammatory and immunosuppressive activity. To elucidate the mechanisms underlying α-MSH-induced immunosuppression, we investigated whether α-MSH affects dendritic cell/T cell communication, as especially this interaction has an important role in the regulation of immune responses. Here, we show that α-MSH, by binding to MC-1R, induced tolerogenic dendritic cells, which were capable of expanding CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs) in vitro, as well as in vivo. Notably, those α-MSH-induced Tregs were functional as they efficiently inhibited cutaneous contact allergy and ongoing psoriasis-like skin inflammation in mice. Furthermore, α-MSH induced tolerogenic dendritic cells capable of generating functional Tregs in human blood. Interestingly, human Tregs expanded via α-MSH-stimulated dendritic cells suppressed the proliferation and cytokine secretion of pathogenic T-helper-17 (Th17) cells from individuals with psoriasis. Taken together, these data indicate that α-MSH induced immunosuppressive Tregs in vitro and in vivo, which inhibited disease progression in a mouse model of psoriasis-like skin inflammation and suppressed the activation and proliferation of effector T cells from subjects with psoriasis.

Categorization of traditional medicinal plants on inflammation-regulatory and anti-tumor activities by differenzial cytokine expression in dendritic cells

Traditional medicinal plants (TMP) are increasingly recognized for use in public health care throughout the world. However, systematic investigation of TMPs on specific and heath care-applicable immuno-regulatory activities is limited. Dendritic cells (DCs), a key type of professional antigen presenting cells are key mediators in human's immune systems. Therefore, DCs are considered by many as a viable pharmacological platform or target for evaluating TMP's immuno-regulatory activities. The objective of this study is to evaluate the regulatory activities of specific TMPs on cytokine regulation in DCs and anti-tumor activities in orthotopic mammary tumor model. Our results show that a number of extracts of test Taiwan specialty medicinal herbs exhibited an inhibitory activity on LPS-induced expression of IL-6 and IL-12 in mouse DCs. In addition, these herbal extracts were categorized into several functional sub-groups based on their capacities to regulate cytokine expression. In an orthotopic mammary tumor model, the extract of TMP1 effectively suppressed primary tumor growth. The extracts of both TMP1 and TMP2 suppressed mammary tumor metastasis, and the results were further confirmed by a mammary tumor resection model. Taken together, our results suggest that TMP1 and TMP2 may warrant further investigation for potential application as anti-tumor natural product agents.

α-1 Antitrypsin Promotes Semimature, IL-10–Producing and Readily Migrating Tolerogenic Dendritic Cells

Tolerogenic IL-10-positive CCR7-positive dendritic cells (DC) promote T regulatory (Treg) cell differentiation upon CCR7-dependent migration to draining lymph nodes (DLN). Indeed, in human DC deficiencies, Treg levels are low. α-1 antitrypsin (AAT) has been shown to reduce inflammatory markers, promote a semimature LPS-induced DC phenotype, facilitate Treg expansion, and protect pancreatic islets from alloimmune and autoimmune responses in mice. However, the mechanism behind these activities of AAT is poorly understood. In this study, we examine interactions among DC, CD4(+) T cells, and AAT in vitro and in vivo. IL-1β/IFN-γ-mediated DC maturation and effect on Treg development were examined using OT-II cells and human AAT (0.5 mg/ml). CCL19/21-dependent migration of isolated DC and resident islet DC was assessed, and CCR7 surface levels were examined. Migration toward DLN was evaluated by FITC skin painting, transgenic GFP skin tissue grafting, and footpad DC injection. AAT-treated stimulated DC displayed reduced MHC class II, CD40, CD86, and IL-6, but produced more IL-10 and maintained inducible CCR7. Upon exposure of CD4(+) T cells to OVA-loaded AAT-treated DC, 2.7-fold more Foxp3(+) Treg cells were obtained. AAT-treated cells displayed enhanced chemokine-dependent migration and low surface CD40. Under AAT treatment (60 mg/kg), DLN contained twice more fluorescence after FITC skin painting and twice more donor DC after footpad injection, whereas migrating DC expressed less CD40, MHC class II, and CD86. Intracellular DC IL-10 was 2-fold higher in the AAT group. Taken together, these results suggest that inducible functional CCR7 is maintained during AAT-mediated anti-inflammatory conditions. Further studies are required to elucidate the mechanism behind the favorable tolerogenic activities of AAT.

Tick-borne flaviviruses impair IRF-1 and type I IFN signaling to inhibit IL-12 production by dendritic cells (170.6)

Abstract Tick-borne encephalitis virus (TBEV), family Flaviviridae, is an emerging pathogen causing ~10,000 human cases of severe CNS disease annually. Dendritic cells (DCs) are early cellular targets of TBEV infection, which may contribute to viral pathogenesis. Here, we examined the cytokine response and maturation profile of murine bone marrow-derived DCs infected with LGTV, a naturally attenuated member of the TBEV serogroup. LGTV infection failed to induce DC maturation or a robust cytokine response. Treatment with LPS or LPS/IFNγ, strong inducers of inflammatory cytokines, resulted in enhanced production of TNFα and IL-6, but suppressed IL-12 in infected DCs when compared to uninfected "bystander" cells or mock-infected controls. Although late suppression of IL-12p40 involved antagonism of type I IFN signaling, early suppression was dependent on IRF-1, a key transcription factor required for anti-flaviviral immunity. LGTV infection did not affect IRF-1 mRNA expression, but rather diminished IRF-1 protein levels and nuclear localization in DCs and reduced IRF-1 transcriptional activity in Huh7 cells. The effect on IRF-1 was also observed in DCs infected with the virulent Sofjin strain of TBEV and in DCs isolated from skin-draining lymph nodes of LGTV-infected Ifnar-/- mice. Thus, IL-12p40 inhibition by LGTV involved coordinated impairment of IRF-1 function and type I IFN signaling. This work identifies IRF-1 as a novel target of flavivirus-mediated immune evasion.

MTORC2 negatively regulates DC PD-L1 and IL-10 through SOCS3 and STAT3 (172.34)

Abstract The mammalian Target of Rapamycin (mTOR) is a central regulator of dendritic cells (DC) that functions in two independent complexes, mTOR complex (mTORC) 1 and 2. Rapamycin (RAPA) is a selective inhibitor of mTORC1, whereas novel ATP-competitive mTORC1/2 inhibitors (Torin1) inhibit both complexes. The immunoregulatory function of RAPA-resistant mTORC2 in DC is unknown. C57BL/6, PD-L1-/-, IL-6-/-, IL-10-/-, IL-12/23p40-/-, Ebi3-/-, interferon regulatory factor (IRF)1-/-, or FoxO1/3/4-/- bone marrow cells were cultured in GM-CSF and IL-4 to generate CD11c+ DC. RAPA or Torin1 was added on d2, and LPS added on d7. DC phenotype and signaling was assessed (d8) by flow cytometry and immunoblot, respectively. While RAPA reduced PD-L1, mTORC1/2 inhibition selectively upregulated PD-L1 expression on DC in a STAT3-dependent manner in unstimulated and LPS-stimulated DC. Whereas RAPA reduced IL-10 secretion, mTORC1/2 inhibition augmented IL-10 secretion following LPS stimulation. The PD-L1 regulator, IRF1, and FoxO, a STAT3 regulator, were not required for PD-L1 upregulation. PD-L1 upregulation on mTORC1/2-inhibited DC did not require autocrine IL-6, IL-10, IL-12/23, or IL-27. SOCS3, a negative regulator of STAT3, was reduced dramatically in mTORC1/2-inhibited, but not RAPA-exposed DC. mTORC2 negatively regulates STAT3 in DC through SOCS3. Blockade of mTORC2 signaling enhances PD-L1 expression and IL-10 secretion. These novel findings establish mTORC2 as a key regulator of DC function.

Distinct APCs Explain the Cytokine Bias of α-Galactosylceramide Variants In Vivo

α-Galactosylceramide represents a new class of vaccine adjuvants and immunomodulators that stimulate NKT cells to secrete Th1 and Th2 cytokines. Synthetic variants with short or unsaturated acyl chains exhibit a striking Th2 bias in vivo but no evidence of defect in TCR signaling or stimulation of NKT cells in vitro. Using cd1d1(fl/fl) mice, we demonstrated that distinct APC types explained the cytokine bias in vivo. Whereas NKT stimulation by α-Galactosylceramide required CD1d expression by dendritic cells (DCs), presentation of the Th2 variants was promiscuous and unaffected by DC-specific ablation of CD1d. This DC-independent stimulation failed to activate the feedback loop between DC IL-12 and NK cell IFN-γ, explaining the Th2 bias. Conversely, forced presentation of the Th2 variants by DC induced high IL-12. Thus, lipid structural variations that do not alter TCR recognition can activate distinct Th1 or Th2 cellular networks by changing APC targeting in vivo.

Transplant tolerance is associated with reduced expression of cystathionine-γ-lyase that controls IL-12 production by dendritic cells and TH-1 immune responses

AbstractAntigen-activated T lymphocytes undergo an immune or tolerogeneic response in part according to the activation status of their antigen-presenting cells. However, factors controlling the activation of antigen-presenting cells are not fully understood. In this study, we demonstrate that immune tolerance after organ allotransplantation in the rat is associated with a repressed intragraft expression of several enzymes of the trans-sulfuration pathway, including cystathionine γ-lyase (CSE). The pharmacologic blockade of CSE with propargylglycine delayed heart allograft rejection and abrogated type IV hypersensitivity but did not modify antibody responses, and was associated with a selective inhibition of the TH-1 type factors T-bet, IL-12, and IFN-γ. IL-12 repression could also be induced by propargylglycine in vitro in monocytes and dendritic cells (DCs), a phenomenon not mediated by changes to nuclear factor-κ B or hydrogen sulfide but that occurred together with a modulation of intracellular cysteine content. Intracellular cysteine levels were predominantly controlled in DCs by CSE activity, together with extracellular import via the Xc− transporter. Our results indicate that CSE plays a critical role in regulating IL-12 in monocytes and DCs and is down-modulated in transplant tolerance, presumably participating in the maintenance of the tolerant state.

Carboxymethylpachymaran enhances immunologic function of dendritic cells cultured in two kinds of hepatoma carcinoma cell line’s supernatant via nuclear factor κB/Rel pathway

To study the immunologic function of dendritic cells (DCs) cultured in two kinds of hepatoma cell line's supernatant and the enhancing effects of carboxymethylpachymaran (CMP) on DCs. DCs were harvested after stimulation by granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4 from umbilical cord blood using density-gradient centrifugation method. Cultured supernatant of two hepatoma cell lines (HepG2 and HepG2.2.15) were collected for condition medium (CM) according to a volume ratio of supernatant to incomplete RPMI-1640 medium, which was 3:1. CMP was dissolved in incomplete RPMI-1640 medium. Experimental groups were divided according to the culture medium, either CM or with CMP in it. DCs subsets CD83, CD86, CD1a, and d-related human leukocyte antigens (HLA-DR) were analyzed by flow cytometry. The proliferation ability of allogeneic T cells in mixed lymphocyte reaction (MLR) stimulated by DCs was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) analysis. IL-12p70, interferon-γ (IFN-γ), and nuclear factor κB (NF-κB) were detected by enzyme-linked immunosorbent assay analysis. The proliferation of lymphocytes and secreting level of IL-12 and expression of phenotype of DCs cultured in two kinds of CM were lower than those of normal group (P <0.01). Compared with the normal group, groups treated with CMP showed a higher expression level of DCs subsets, lymphocyte reproductive activity, as well as IL-12 and IFN-γ secretion levels. Groups treated with CMP also demonstrated higher levels of DCs phenotype expression and IL-12 and IFN-γ secretion in supernatant of MLR and higher lymphocyte reproductive activity compared with CM group (P <0.05). Compared with the normal group, the expression level of NF-κB in DCs nuclear was higher in CMP groups but lower in two CM groups (P <0.05). After CMP was added, the NF-κB expression levels of two CM groups were increased compared with levels before CMP was added (P <0.05). However, there was no significant difference between the two CM groups (P >0.05). Two kinds of hepatoma cell line's supernatant can inhibit the immunologic function of DCs. This suppressive effect may be related to the inhibition of NF-κB/Rel pathway. CMP may up-regulate the DCs function by activating the NF-κB/Rel pathway.

Helicobacter pylori DNA's anti-inflammatory effect on experimental colitis

Our laboratory has demonstrated a clinical inverse association between H. pylori infection and inflammatory bowel disease (IBD). In our most recent work we described a possible mechanism by which H. pylori can reduce the risk of developing IBD. Specifically, we were able to demonstrate the immuno-regulatory properties of the H. pylori genome and its ability to downregulate inflammatory responses through interaction with mucosal dendritic cells both in an in vitro and in vivo model. Furthermore, we were able to demonstrate the ability of H. pylori DNA to downregulate dendritic cell production of IL-12 and type I interferon, two pro-inflammatory cytokines. In the present work, we conducted further studies to examine the unique properties of the H. pylori genome and the exact mechanism through which it interacts with dendritic cells. Our data highlight a specific immuno-regulatory sequence (IRS), TTTAGGG, which occurs significantly more frequently as compared with other IRS sequences and is unique to the H. pylori genome. Additionally, we illustrate that H. pylori DNA has no effect on modulating the TLR-4 dependent LPS-induction of dendritic cell IL-12 production. This indicates that the inhibitory effect of H. pylori genomic DNA is restricted to the TLR-9 signaling pathway that senses bacterial DNA. In conclusion, the findings of this addendum strengthen the evidence for unique immunoregulatory properties of the H. pylori genome and revealed the importance of TLR-9 mediated mechanism in the pathogenesis of IBD.

Gene silencing of IL-12 in dendritic cells inhibits autoimmune arthritis

BackgroundWe have previously demonstrated that immune modulation can be accomplished by administration of gene silenced dendritic cells (DC) using siRNA. In this study, we demonstrate the therapeutic utilization of shRNA-modified DC as an antigen-specific tolerogenic vaccine strategy for autoimmune arthritis.MethodsA shRNA that specifically targets IL-12 p35 was designed and cloned into a plasmid vectors (IL-12 shRNA). Bone marrow-derived DC from DBA/1 mice were transfected with the IL-12 shRNA construct in vitro. Mice with collagen II (CII)-induced arthritis (CIA) were treated with the modified DCs expressing the shRNA. Recall response and disease progression were assessed.ResultsAfter gene silencing of IL-12 in DC, DC were shown to selectively inhibit T cell proliferation on recall responses and in an MLR. In murine CIA, we demonstrated that administration of IL-12 shRNA-expressing DC that were pulsed with CII inhibited progression of arthritis. The therapeutic effects were evidenced by decreased clinical scores, inhibition of inflammatory cell infiltration in the joint, and suppression of T cell and B cell responses to CII.ConclusionWe demonstrate a novel tolerance-inducing protocol for the treatment of autoimmune inflammatory joint disease in which the target antigen is known, utilizing DNA-directed RNA interference.

Abstract P304: Salvianolic Acid B Suppresses Human Monocyte-Derived Dendritic Cell Maturation via PPARγ Activation

Background and purpose: Salvianolic acid B (Sal B), a water-soluble antioxidant derived from a medicinal herb, is known to be effective in the prevention of atherosclerosis. Here, we tested the hypothesis that the anti-atherosclerotic effect of Sal B might be mediated by suppressing human monocyte-derived dendritic cells (DCs) maturation. Experimental approach: DCs was derived by incubating purified human monocytes with GM-CSF and IL-4. DCs was pre-incubated with or without Sal B and stimulated by oxidized low density lipoprotein (ox-LDL) in the presence or absence of PPAR-γ siRNA. Expression of DCs membrane molecules were analyzed by FACS, cytokines were measured by ELISA, and TLR4 associated signaling pathway was determined by Western blotting. Key results: Ox-LDL promoted DCs maturation, stimulated CD40, CD86, CD1a, HLA-DR expression and IL-12, IL-10, TNF-α production and upregulated TLR4 signaling. These effects could be significantly inhibited by Sal B. Sal B also triggered PPAR-γ activation and promoted PPAR-γ nuclear translocation, attenuated ox-LDL-induced upregulation of TLR4 and myeloid differentiation primary-response protein 88 (MyD88), and inhibited downstream p38-MAPK signaling cascade. Knocking down PPAR-γ through siRNA transfection significantly blocked above mentioned effects of Sal B. Conclusions and implications: Our data suggested that Sal B effectively suppressed ox-LDL-induced DCs maturation through PPAR-γ activation.

Emergency granulopoiesis promotes neutrophil-dendritic cell encounters that prevent mouse lung allograft acceptance

AbstractThe mechanisms by which innate immune signals regulate alloimmune responses remain poorly understood. In the present study, we show by intravital 2-photon microscopy direct interactions between graft-infiltrating neutrophils and donor CD11c+ dendritic cells (DCs) within orthotopic lung allografts immediately after reperfusion. Neutrophils isolated from the airways of lung transplantation recipients stimulate donor DCs in a contact-dependent fashion to augment their production of IL-12 and expand alloantigen-specific IFN-γ+ T cells. DC IL-12 expression is largely regulated by degranulation and induced by TNF-α associated with the neutrophil plasma membrane. Extended cold ischemic graft storage enhances G-CSF–mediated granulopoiesis and neutrophil graft infiltration, resulting in exacerbation of ischemia-reperfusion injury after lung transplantation. Ischemia reperfusion injury prevents immunosuppression-mediated acceptance of mouse lung allografts unless G-CSF–mediated granulopoiesis is inhibited. Our findings identify granulopoiesis-mediated augmentation of alloimmunity as a novel link between innate and adaptive immune responses after organ transplantation.

Intravenous anesthetic propofol suppresses prostaglandin E2 production in murine dendritic cells

Propofol is an intravenous anesthetic that is widely used for anesthesia and sedation. Dendritic cells (DC) are one of the crucial immune cells that bridge innate and adaptive immunity, in which DC process antigens during innate immune responses to present them to naïve T-cells, leading to an establishment of adaptive immunity. Prostaglandin (PG)-E2 may be secreted by DC into the microenvironment, considerably influencing DC phenotype and function, and thus determining the fate of adaptive immunity. Since propofol suppresses PGE2 production in murine macrophages, the primary purpose of the present study was to determine whether propofol also suppresses PGE2 production in DC. Assuming a positive finding of such suppression, we tested whether this also leads to alterations of interleukin (IL)-12 and IL-10 production and DC surface marker expression, both of which can be modulated by PGE2. In bone marrow-derived DC, propofol significantly suppressed the PGE2 production after lipopolysaccharide stimulation. Cyclo-oxygenase (COX) protein expression and arachidonic acid release were unaffected, while COX enzyme activity was significantly inhibited by propofol. The propofol-induced COX inhibition did not lead to the increased production of cysteinyl leukotrienes and leukotriene-B4. Endogenous COX inhibition with propofol, as well as with the selective COX-2 inhibitor, NS-398, did not affect IL-12 and IL-10 production from DC. The surface expression of I-Ab and CD40 on DC was not changed, while that of CD86 slightly increased, with both propofol and NS-398; expression of CD80 was not affected with propofol, but increased slightly with NS-398. Finally, endogenous COX inhibition with either propofol or NS-398 did not significantly affect the ability of DC to induce allogeneic T-cell proliferation. It is concluded that the intravenous anesthetic propofol suppresses COX enzyme activity in DC, with no consequences with respect to IL-12/IL-10 production and allogeneic T-cell proliferation, while minimal consequences were observed in surface molecule expression.

Critical Roles for LIGHT and Its Receptors in Generating T Cell-Mediated Immunity during Leishmania donovani Infection

LIGHT (TNFSF14) is a member of the TNF superfamily involved in inflammation and defence against infection. LIGHT signals via two cell-bound receptors; herpes virus entry mediator (HVEM) and lymphotoxin-beta receptor (LTβR). We found that LIGHT is critical for control of hepatic parasite growth in mice with visceral leishmaniasis (VL) caused by infection with the protozoan parasite Leishmania donovani. LIGHT-HVEM signalling is essential for early dendritic cell IL-12/IL-23p40 production, and the generation of IFNγ- and TNF-producing T cells that control hepatic infection. However, we also discovered that LIGHT-LTβR interactions suppress anti-parasitic immunity in the liver in the first 7 days of infection by mechanisms that restrict both CD4+ T cell function and TNF-dependent microbicidal mechanisms. Thus, we have identified distinct roles for LIGHT in infection, and show that manipulation of interactions between LIGHT and its receptors may be used for therapeutic advantage.

Effects of Gekko Sulfated Polysaccharide–Protein Complex on the Defective Biorheological Characters of Dendritic Cells Under Tumor Microenvironment

We previously isolated a sulfated polysaccharide-protein complex from Gekko swinhonis Guenther, a traditional Chinese medicine, and have demonstrated its direct anti-cancer effect on human hepatocellular carcinoma cell line SMMC-7721. Here we investigated the effects of Gekko sulfated polysaccharide-protein complex (GSPP) on the defective biorheological characters of dendritic cells (DCs) under SMMC-7721 microenvironment. Our findings have shown that the biorheological properties of DCs were severely impaired by SMMC-7721 microenvironment, including decreased cell deformability, migration, and electrophoresis mobility, increased osmotic fragilities, and changed organizations of cytoskeletal proteins. We also found decreased secretion of interleukin (IL)-12 and increased secretion of IL-10 in DCs. However, supernatant collected from nonmalignant liver cells had no effect on these parameters. SMMC-7721 cells were treated with GSPP and the supernatant was used to culture DCs. We found that the defective biorheological parameters of DCs, except for osmotic fragility, were partially or completely improved. The secretion of IL-12 did not change as compared with that of DCs in SMMC-7721 microenvironment, but the secretion of IL-10 was resumed to the control level. Our results indicate that GSPP could partially restore the defective biorheological characteristics of DCs via modifying the tumor microenvironment and decreasing the secretion of IL-10 of DCs.