Immune Functions Of Dendritic Cells Research Articles

Combined Photothermal Therapy and Cancer Immunotherapy by Immunogenic Hollow Mesoporous Silicon-shelled Gold Nanorods

Hyperthermia can be integrated with tumor-killing chemotherapy, radiotherapy and immunotherapy to give rise to an anti-tumor response. To this end, a nano-delivery system is built, which can connect hyperthermia and immunotherapy. On this basis, the impact of such a combination on the immune function of dendritic cells (DCs) is explored. The core of this system is the photothermal material gold nanorod (GNR), and its surface is covered with a silica shell. Additionally, it also forms a hollow mesoporous structure using the thermal etching approach, followed by modification of targeted molecule folic acid (FA) on its surface, and eventually forms a hollow mesoporous silica gold nanorod (GNR@void@mSiO2) modified by FA. GNR@void@mSiO2-PEG-FA (GVS-FA) performs well in photothermal properties, drug carriage and release and tumor targeting performance. Furthermore, the thermotherapy of tumor cells through in vitro NIR irradiation can directly kill tumor cells by inhibiting proliferation and inducing apoptosis. GVS-FA loaded with imiquimod (R837) can be used as a adjuvant to enhance the immune function of DCs through hyperthermia.

Melatonin attenuates lipopolysaccharide-induced immune dysfunction in dendritic cells

Melatonin, a ubiquitous hormone, is principally secreted from pineal gland in mammals and possesses strong antioxidant and anti-inflammatory properties. However, its specific roles in the immune functions of dendritic cells (DCs) during acute lung injury (ALI) remain unknown. In this study, we found that melatonin restored the body weight, decreased the lung weight/body weight ratio, alleviated the histopathological lung injury, and decreased the levels of cytokines (tumor necrosis factor-α (TNF-α), interleukin (IL)-12p70, IL-17, and IL-10) in bronchoalveolar lavage fluid of the lipopolysaccharide (LPS)-induced ALI murine model. Moreover, melatonin inhibited the major histocompatibility complex II (MHCII) expression of lung CD11b+ DCs after LPS challenge in vivo. In vitro, melatonin reversed the shape index, promoted the endocytosis, and inhibited phenotypic expression of MHCII, CD40, CD80, and CD86 in LPS-activated DCs. Furthermore, melatonin decreased the expression of an activated marker, CD69, and the secretion of pro-inflammatory cytokines (TNF-α, IL-12p70, and IL-17) after LPS challenge. It hampered the LPS-activated DCs migration by downregulating the C–C chemokine receptor 7 (CCR7) expression, and then weakened the ability of LPS-induced DCs to stimulate allogeneic CD4+ T cell proliferation. Melatonin shaped the immune function of DCs in a nuclear factor erythroid-2-related factor 2 (Nrf-2)/heme oxygenase-1 (HO-1) axis-dependent manner. These findings indicate that melatonin protects DCs from ALI-induced immunological stress and may be used to develop novel DC-targeting strategies for ALI therapy.

The combination of gemcitabine and ginsenoside Rh2 enhances the immune function of dendritic cells against pancreatic cancer via the CARD9-BCL10-MALT1 / NF-κB pathway

Cold tumor immune microenvironment (TIME) of pancreatic cancer (PC) with minimal dendritic cell (DC) and T cell infiltration can result in insufficient immunotherapy and chemotherapy. While gemcitabine (GEM) is a first-line chemotherapeutic drug for PC, its efficacy is reduced by immunosuppression and drug resistance. Ginsenoside Rh2 (Rh2) is known to have anti-cancer and immunomodulatory properties. Combining GEM with Rh2 may thus overcome immunosuppression and induce lasting anti-tumor immunity in PC. Here, we showed that after GEM−Rh2 therapy, there was significantly greater tumor infiltration by DCs. Caspase recruitment domain-containing protein 9 (CARD9), a central adaptor protein, was strongly up-regulated DCs with GEM−Rh2 therapy and promoted anti-tumor immune responses by DCs. CARD9 was found to be a critical target for Rh2 to enhance DC function. However, GEM−Rh2 treatment did not achieve the substantial anti-PC efficacy in CARD9−/− mice as in WT mice. The adoptive transfer of WT DCs to DC-depleted PC mice treated with GEM−Rh2 elicited strong anti-tumor immune responses, although CARD9−/− DCs were less effective than WT DCs. Our results showed that GEM−Rh2 may reverse cold TIME by enhancing tumor immunogenicity and decreasing the levels of immunosuppressive factors, reactivating DCs via the CARD9-BCL10-MALT1/ NF-κB pathway. Our findings suggest a potentially feasible and safe treatment strategy for PC, with a unique mechanism of action. Thus, Rh2 activation of DCs may remodel the cold TIME and optimize GEM chemotherapy for future therapeutic use.

Selenoprotein K Is Essential for the Migration and Phagocytosis of Immature Dendritic Cells.

Selenoprotein K (SELENOK) is an endoplasmic reticulum stress (ERS)-regulated protein required for the calcium (Ca2+) flux-mediated migration of T cells and neutrophils, and the migration and phagocytosis of macrophages and microglia. However, the effect of SELENOK on the regulation of the immune function of dendritic cells (DCs), including immature DCs (imDCs) and mature DCs (mDCs), is still unclear. In this study, imDCs prepared from SELENOK knockout mice were used to evaluate the effect of SELENOK on the migration and phagocytosis of imDCs. The results showed that ERS-induced downregulation of imDCs phenotypic markers led to a reduction in Ras homolog gene family member A (RhoA)-dependent migration and enhanced Ca2+/CD205-mediated phagocytosis. SELENOK deficiency-induced upregulation of selenoprotein S (SELENOS) attenuated ERS levels in imDCs. An increase in Ca2+ levels resulted in increased migration and decreased phagocytosis with or without ERS conditions. The migration was RhoA-dependent, and Ca2+ or CD205 was associated with regulating phagocytosis in imDCs. Our study found that SELENOK is required for imDC migration and phagocytosis.

JAK2 gene knockout inhibits corneal allograft rejection in mice by regulating dendritic cell-induced T cell immune tolerance

Corneal allograft rejection can be seen in some patients after corneal transplantation. The present study intends to investigate whether JAK2 gene knockout affects corneal allograft rejection through regulation of dendritic cells (DCs)-induced T cell immune tolerance. In order to identify the target gene related to corneal allograft rejection, high-throughput mRNA sequencing and bioinformatics analysis were performed. JAK2 knockout mice were constructed and subjected to corneal allograft transplantation. The incidence of immune rejection was observed, the percentage of CD4+ T cells was detected, and the expression of Th1 cytokine interferon γ (IFN-γ) was determined. Flow cytometry and ELISA were performed to analyze the effects of JAK2 gene knockout on bone marrow-derived DCs (BMDCs). JAK2 was the target gene related to corneal allograft rejection. JAK2 gene knockout contributed to significantly prolonged survival time of corneal grafts in mice and inhibited corneal allograft rejection. The in vitro cell experiment further confirmed that JAK2 gene knockout contributed to the inactivation of CD4+ T cells and induced IFN-γ expression, accompanied by inhibition of DC immune function, development, maturation, and secretion of inflammatory cytokines. Collectively, JAK2 gene knockout inactivates CD4+ T cells to decrease IFN-γ expression, as well as inhibits DC development, maturation, and secretion of inflammatory cytokines, thereby reducing corneal allograft rejection.

Gpr174 Knockout Alleviates DSS-Induced Colitis via Regulating the Immune Function of Dendritic Cells.

BackgroundDysfunction of the immune system would disturb the intestinal homeostasis and lead to inflammatory bowel disease (IBD). Dendritic cells (DCs) help maintain intestinal homeostasis and immediately respond to pathogens or injuries once the mucosa barriers are destroyed during IBD. G protein-coupled receptors(GPR)174 is an essential regulator of immunity that is widely expressed in most immune cells, including DCs. However, the role of GPR174 in regulating the immune function of DC in colitis has not been investigated.MethodsDextran sodium sulfate (DSS) was administered to establish the mice colitis model. Data of weight, length of colon, disease activity index (DAI), and macroscopic scores were collected. The flow cytometry was used to detect the infiltrations of T cells and DCs, the mean fluorescence intensity (MFI) of CD80, CD86, CD40, and major histocompatibility complex-II (MHC-II). And T cells proliferataion was measured by carboxyfluorescein diacetate succinimidyl ester (CFSE). The expression of cytokines (tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-10 (IL-10), interferon-γ (IFN-γ), interleukin -4 (IL-4)) and GPR174 mRNA were measured by Elisa, quantitative polymerase chain reaction (qPCR), and immunofluorescence. RNA of bone-marrow-derived dendritic cells (BMDCs) was extracted for sequencing. Adoptive transfer of BMDCs was administrated intravenously.ResultsGpr174-/- mice exposed to 3% DSS showed significant alleviation characterized by reduced loss of weight, more minor colon damage, and better DAI and macroscopic scores. The expression of pro-inflammatory cytokines (TNF-α, IL-6) decreased, while anti-inflammatory cytokine (IL-10) increased compared with WT mice. In vitro, Gpr174-/- BMDCs showed less maturity, with a declined expression of MHC-II, CD80, CD86 and reduced TNF-α, higher IL-10 after LPS stimulation. Gpr174-/- BMDCs were less capable of activating OT-II naïve CD4+ T cells than WT BMDCs and induced more Th0 cells to differentiate into Treg while less into Th1. Furthermore, the transcriptome sequencing analysis exhibited that Gpr174 participated in TNF-α (NF-κB) signaling, leukocyte transendothelial migration, and Th1/Th2 cell differentiation pathways. Adoptive transfer of Gpr174-/- BMDCs to WT mice ameliorated DSS-induced colitis.ConclusionOur study indicated that GPR174 was involved in the pathogenesis of IBD by regulating the maturation of the dendritic cells to maintain immune homeostasis. TNF-α (NF-κB) signaling pathway, leukocyte transendothelial migration, and Th1/Th2 cell differentiation pathways may be the target pathway.

Immune Modulatory Effect of Outer Membrane Vesicles Derived from Salmonella on Mouse Bone Marrow-Derived Dendritic Cells

To study the effect of outer membrane vesicles (OMVs) derived from Salmonella typhimurium (ST) on the ultrastructural features and immune function of dendritic cells (DC). Mice bone marrow cells were collected aseptically, and myeloid DC were generated by the combined induction and amplification with recombinant mouse granulocyte-macrophage colony-stimulating factor (GM-CSF) and recombinant mouse interleukin-4 (rm IL-4). Cell morphology was observed under inverted phase contrast microscope and the phenotype was identified with flow cytometry. ST-OMVs were isolated through ultracentrifugation. The survival rate of DC was assessed with CCK-8 assay, and the stimulus concentration of OMVs was henceforth determined. The ultrastructural characteristics of DC loaded with OMVs were observed with transmission electron microscopy. The cytokine secretion, surface molecule expression and phagocytic capacity of DC were examined with flow cytometry. The DC induced and amplified in vitro displayed typical DC phenotype in morphological analysis and the purity of DC exceeded 85%. Transmission electron microscopy showed that there were large numbers of protrusions on the cell surface. After stimulation with ST-OMVs, it was observed that the dendritic structures on the surface of DC were reduced and a large number of phagolysosomes were found in the cytoplasm. In addition, increased numbers of mitochondria, swelling and typical apoptosis were observed. After treatment with ST-OMVs at 5 μg/mL and 10 μg/mL, the secretion of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) of DC increased significantly ( P<0.05). Furthermore, the immature DC could differentiate into mature DCs after stimulation with ST-OMVs, which were characterized by a decrease in phagocytic capacity ( P<0.05) and an upregulation of phenotypic markers ( P<0.05). ST-OMVs can stimulate DC to produce TNF-α and IL-1β and promote DC maturation and antigen presentation.

TNF-\u03b1-induced protein 8-like 2 negatively regulates the immune function of dendritic cells by suppressing autophagy via the TAK1/JNK pathway in septic mice

Tumor necrosis factor (TNF)-α-induced protein 8-like 2 (TIPE2) is a newly discovered negative immunoregulatory protein that is involved in various cellular immune responses to infections. However, the underlying mechanism by which TIPE2 affects the immune function of dendritic cells (DCs) is not yet understood. This study aimed to determine the correlations among DCs TIPE2 expression, autophagic activity and immune function in the context of sepsis. In addition, the signaling pathway by which TIPE2 regulates autophagy in DCs was investigated. We reported for the first time that TIPE2 overexpression (knock-in, KI) exerted an inhibitory effect on autophagy in DCs and markedly suppressed the immune function of DCs upon septic challenge both in vitro and in vivo. In addition, TIPE2 knockout (KO) in DCs significantly enhanced autophagy and improved the immune response of DCs in sepsis. Of note, we found that the transforming growth factor-β (TGF-β)-activated kinase-1 (TAK1)/c-Jun N-terminal kinase (JNK) pathway was inhibited by TIPE2 in DCs, resulting in downregulated autophagic activity. Collectively, these results suggest that TIPE2 can suppress the autophagic activity of DCs by inhibiting the TAK1/JNK signaling pathway and further negatively regulate the immune function of DCs in the development of septic complications.

“Dialogue” between Caco-2 and DCs regulated by Ganoderma atrum polysaccharide in intestinal-like Caco-2/DCs co-culture model

The previous research has indicated that Ganoderma atrum polysaccharide (PSG-1) indirectly affects the immune function of dendritic cells (DCs) in intestinal-like Caco-2/DCs co-culture model, in which NF-κB and MAPK pathway play an essential role. To explore the interaction of Caco-2 in the interaction between the intestinal epithelium and its internal immune cells, the intestinal-like Caco-2/DCs co-culture model was developed. All transcripts of Caco-2 treated with or without PSG-1 were globally screened by RNA-seq. The expression of 452 genes regulated by PSG-1 was statistically significant, the counts of up-regulated and down-regulated genes were 198 and 256, respectively. According to KEGG analysis, tumor necrosis factor (TNF)-α and NF-κB signaling pathways of Caco-2 were selected to elucidate the mechanism of interaction between Caco-2/DCs induced by PSG-1. After the addition of TNF-α inhibitor Apremilast and NF-κB inhibitor BAY11-70821 in Caco-2, expression of cytokines (TNF-α, IL-6, IL-1β, IL-10), chemokines (RANTES, MIP-1α, MCP-1), and the key proteins of MAPK and NF-κB pathways of DCs were all reduced. In summary, “dialogue” between Caco-2 and DCs was regulated by PSG-1 through TNF-α and NF-κB signaling pathways of Caco-2 in the model.

Selenium Regulation of the Immune Function of Dendritic Cells in Mice Through the ERK, Akt and RhoA/ROCK Pathways.

Selenium levels can regulate the function of T cells, macrophages, B cells, natural killer cells and other immune cells. However, the effect of selenium on the immune function of dendritic cells (DCs) isolated from selenium-supplemented mice is unknown. In this study, C57BL/6J mice were randomly divided into three groups and fed diets containing low (0.08ppm), medium (0.25ppm) or high (1ppm) selenium levels for 8weeks. Immature (imDCs) and mature (mDCs) dendritic cells were then isolated from the bone marrow. Next, the migration, phagocytic capacity and mixed lymphocyte reaction (MLR) for imDCs and mDCs were detected by transwell and flow cytometry. The levels of C-C chemokine receptor type 7 (CCR7), major histocompatibility complex II (MHCII) and reactive oxygen species (ROS) were assayed by flow cytometry. F-actin and superoxide dismutase (SOD) activity was detected by fluorescence microscopy and SOD assay kit, respectively. In addition, the extracellular signal-regulated kinase (ERK), Akt, Ras homolog gene family member A/Rho-associated protein kinase (RhoA/ROCK) signalling, selenoprotein K (SELENOK) and glutathione peroxidase 1 (GPX1) levels were measured by western blot analysis. The results indicated that selenium deficiency enhanced the migration of imDCs by ROS and SELENOK-mediated ERK, Akt and RhoA/ROCK pathways but impaired the antigen uptake of imDCs. Although a high selenium level inhibited the migration of imDCs, it had no effect on phagocytic capacity. For mDCs, low selenium levels impaired free migration, and high levels inhibited the chemotactic migration involved in F-actin and CCR7, respectively. Low and high selenium levels impaired the MLR by inhibiting MHCII surface localisation, which might be related to ROS- and SELENOK-mediated ERK, Akt and RhoA/ROCK signalling pathways. In summary, selenium may regulate the immune function of mouse DCs through the ROS- and SELENOK-mediated ERK, Akt and RhoA/ROCK signalling.

Dynamic metabolic reprogramming in dendritic cells: An early response to influenza infection that is essential for effector function.

Infection with the influenza virus triggers an innate immune response that initiates the adaptive response to halt viral replication and spread. However, the metabolic response fueling the molecular mechanisms underlying changes in innate immune cell homeostasis remain undefined. Although influenza increases parasitized cell metabolism, it does not productively replicate in dendritic cells. To dissect these mechanisms, we compared the metabolism of dendritic cells to that of those infected with active and inactive influenza A virus and those treated with toll-like receptor agonists. Using quantitative mass spectrometry, pulse chase substrate utilization assays and metabolic flux measurements, we found global metabolic changes in dendritic cells 17 hours post infection, including significant changes in carbon commitment via glycolysis and glutaminolysis, as well as mitochondrial respiration. Influenza infection of dendritic cells led to a metabolic phenotype distinct from that induced by TLR agonists, with significant resilience in terms of metabolic plasticity. We identified c-Myc as one transcription factor modulating this response. Restriction of c-Myc activity or mitochondrial substrates significantly changed the immune functions of dendritic cells, such as reducing motility and T cell activation. Transcriptome analysis of inflammatory dendritic cells isolated following influenza infection showed similar metabolic reprogramming occurs in vivo. Thus, early in the infection process, dendritic cells respond with global metabolic restructuring, that is present in inflammatory lung dendritic cells after infection, and this is important for effector function. These findings suggest metabolic switching in dendritic cells plays a vital role in initiating the immune response to influenza infection.

Flightless-1 promotes lung CD103+ cDC phagocytosis and migration

Abstract Dendritic cells are specialized antigen-presenting cells integral for bridging the innate and adaptive immune responses. Critical to dendritic cell function is the need for a dynamic actin cytoskeleton. Flightless-1 is an actin capping protein linked to processes vital for dendritic cell immune functions including cell extension formation, phagocytosis, cell migration, and cell adhesion. Consistent with an important role in actin dynamics, whole body Flightless-1 knockouts are embryonic lethal. To enable further study of Flightless-1 in the immune response, we made mice with dendritic cell Flightless-1 deficiency using the CD11c-CRE driver. Homeostatic cDC1 and cDC2 populations in the spleen and lymph nodes were unchanged in DC-Flightless-1 knockouts relative to control animals. However, DC-Flightless-1 ablation led to a developmental disadvantage when in competition with WT DCs in mixed bone marrow chimeras. Upon LPS challenge in the airways, the Flightless-deficient cDC1 population showed reduced phagocytosis and migration to the lung draining lymph nodes. The DC migratory defect in the absence of Flightless-1 was supported by decreased CCR7 expression in both cDC1 and cDC2 populations. We hypothesize that the observed defects in phagocytosis and migration in Flightless-1-deficient dendritic cells are due to an altered actin cytoskeleton, which may also affect other actin-based immune structures. Current experiments are testing this hypothesis, and investigating the ability of Flightless-deficient DC to prime T cell responses.

Leucine-Rich Repeat Kinase 2 Controls Inflammatory Cytokines Production through NF-κB Phosphorylation and Antigen Presentation in Bone Marrow-Derived Dendritic Cells.

Leucine-rich repeat kinase 2 (LRRK2) is the causal molecule of familial Parkinson’s disease. Although the characteristics of LRRK2 have gradually been revealed, its true physiological functions remain unknown. LRRK2 is highly expressed in immune cells such as B2 cells and macrophages, suggesting that it plays important roles in the immune system. In the present study, we investigate the roles of LRRK2 in the immune functions of dendritic cells (DCs). Bone marrow-derived DCs from both C57BL/6 wild-type (WT) and LRRK2 knockout (KO) mice were induced by culture with granulocyte/macrophage-colony stimulating factor (GM/CSF) in vitro. We observed the differentiation of DCs, the phosphorylation of the transcriptional factors NF-κB, Erk1/2, and p-38 after lipopolysaccharide (LPS) stimulation and antigen-presenting ability by flow cytometry. We also analyzed the production of inflammatory cytokines by ELISA. During the observation period, there was no difference in DC differentiation between WT and LRRK2-KO mice. After LPS stimulation, phosphorylation of NF-κB was significantly increased in DCs from the KO mice. Large amounts of inflammatory cytokines were produced by DCs from KO mice after both stimulation with LPS and infection with Leishmania. CD4+ T-cells isolated from antigen-immunized mice proliferated to a significantly greater degree upon coculture with antigen-stimulated DCs from KO mice than upon coculture with DCs from WT mice. These results suggest that LRRK2 may play important roles in signal transduction and antigen presentation by DCs.

Mechanism of Telomerase Reverse Transcriptase Regulating Dendritic Cell Immune Function in Proliferation and Cell Cycle of Renal Cell Carcinoma

To select human renal cell carcinoma cell lines VMRC-RCZ After resuscitation, culture and passage, the cell concentration was adjusted to 1 × 106/ml, and the experiment was divided into a control group, a renal cancer cell + DC group (DC group), and a renal cancer cell + DC+ hTERTtransfection group (transfection Group), a total of 3 groups; the recombinant eukaryotic expression plasmid hTERT-IRES2-EGFP was constructed and transfected into mature DC; the renal cancer cell + DC group was transfected with the empty plasmid, and the renal cancer cell + DC+ hTERT transfection group was transfected with the overexpression plasmid The transfection efficiency was detected by RT-PCR method. Cultured for 12 h and 24 h respectively, the percentage of HLA-DR, CD40 and MHC-II molecules in three groups of DC immunophenotypes was determined according to flow cytometry assay, and the cytokines IL-12 and TNF-α expression level, DC apoptosis rate was detected by in situ hybridization, the rate of tumor cell proliferation was measured according to MTT method, and cell cycle was determined through flow cytometry.

Role of dendritic cell-mediated immune response in oral homeostasis: A new mechanism of osteonecrosis of the jaw.

Dendritic cells are an important link between innate and adaptive immune response. The role of dendritic cells in bone homeostasis, however, is not understood. Osteoporosis medications that inhibit osteoclasts have been associated with osteonecrosis, a condition limited to the jawbone, thus called medication-related osteonecrosis of the jaw. We propose that disruption of the local immune response renders the oral microenvironment conducive to osteonecrosis. We tested whether zoledronate (Zol) treatment impaired dendritic cell (DC) functions and increased bacterial load in alveolar bone in vivo and whether DC inhibition alone predisposed the animals to osteonecrosis. We also analyzed the role of Zol in impairment of differentiation and function of migratory and tissue-resident DCs, promoting disruption of T-cell activation in vitro. Results demonstrated a Zol induced impairment in DC functions and an increased bacterial load in the oral cavity. DC-deficient mice were predisposed to osteonecrosis following dental extraction. Zol treatment of DCs in vitro caused an impairment in immune functions including differentiation, maturation, migration, antigen presentation, and T-cell activation. We conclude that the mechanism of Zol-induced osteonecrosis of the jaw involves disruption of DC immune functions required to clear bacterial infection and activate T cell effector response.

Changes of endotoxin tolerant dendritic cell immune function and its effect on sepsis in mouse model

Objective To study the changes of immune function of endotoxin tolerant dendritic cell (ETDC) and to observe its effect on sepsis in mouse model. Methods ETDC were prepared by pretreated bone marrow dendritic cells derived from BALB/c mice with lipopolysaccharide stimulation. The cells were collected and the expressions of surface markers including major histocompatibility complex (MHC)Ⅱ, CD86 and CD11c were detected by flow cytometry. The proliferation rate of T lymphocytes was evaluated by cell counting kit-8 and the concentrations of cytokines in the supernatant were detected by enzyme linked immuno sorbent assay. Afterwards, 36 mice were randomly assigned into 4 groups. The blank control group did not receive any treatment, the sham-operated group underwent simple incision suture, the sepsis group and ETDC reinfusion group underwent cecal ligation and puncture to establish sepsis. Before sepsis model establishment, 0.9% sodium chloride solution or suspension of ETDC and 0.9% sodium chloride were reinfused by tail vein. The serum levels of alanine aminotransferase (ALT) and aspartate transaminase (AST), tumor necrosis factor (TNF)-α, interleukin(IL)-6 and IL-10, and the proportion of help T cell (Th) 17/regulatory T cell (Treg) in spleen of each group were detected. The pathological manifestations of liver, kidney and ileum in each group were observed. T test and χ2 test were used for comparisons between groups. Results The results of flow cytometry showed that MHCⅡ, CD86 and CD11c of ETDC were 70.4%, 43.1%, and 73.1%, respectively, which were significantly lower than those of mature dendritic cell (mDC) (96.1%, 89.5%, and 84.6%, respectively) (χ2=56.47, 83.78, and 23.29, respectively, all P<0.01). The concentrations of IL-10, TNF-α and IL-6 in the supernatant of ETDC were (978.04±56.70), (980.34±111.96) and (12 743.03±865.81) ng/L, respectively, and those of mDC were (741.35±99.23), (1 703.11±117.00) and (19 052.28±1 145.84) ng/L, respectively. The differences were all statistically significant (t=5.073, 10.93, and 10.76, respectively, all P<0.01). The proliferation rates of T lymphocytes co-cultured with ETDC in 1∶5 and 1∶10 ratio group were (676.95±85.99)% and (514.00±106.39)%, respectively, which were lower than those of the mDC group (956.25±127.12)% and (772.07±214.08)%, respectively. The pathological injuries of liver, kidney and ileum in ETDC treatment group were significantly lighter than those in sepsis group. Serum ALT and AST levels in the ETDC reinfusion group were (299.71±36.91) and (690.39±154.92) U/L, respectively, and TNF-α, IL-6 and IL-10 were (0.067±0.005), (0.428±0.051) and (0.058±0.005) ng/L, respectively. Serum ALT and AST levels in the sepsis group were (620.67±69.27) and (1 430.17±134.05) U/L, respectively, and TNF-α, IL-6 and IL-10 were (0.085±0.007), (0.774±0.088) and (0.036±0.005) ng/L, respectively. The differences were all statistically significant (t=11.60, 10.96, 5.991, 8.657, and 8.04, respectively, all P <0.01). The proportion of Treg/Th17 in the ETDC reinfusion group was 23.4%, and that in the sepsis group was 60.8% (χ2=28.69, P<0.01). Conclusion The reinfusion of ETDC has a protective effect on sepsis in mouse model, which may play a negative immune regulatory role by regulating the differentiation of T cells. Key words: Sepsis; Dendritic cells; Endotoxin tolerance

Knockdown of circular RNA FSCN1 impairs dendritic cell immune function through regulating the NFKB and Foxo3 signaling pathways

Abstract Circular RNAs (circRNAs) that are a new class of endogenously expressed non-coding RNAs produced from back splicing with a covalently closed loop structure have been emerging as an important gene regulator in the physiological and pathological development of cells. It remains unknown about roles of circRNAs in DCs. The objective of the study is to investigate the impact of circular RNA FSCN1 (circFSCN1) on dendritic cell immune function. Bone marrow derived dendritic cells were cultured in vitro and circRNA expression was detected by circRNA microarrays and qRT-PCR. The effect of circFSCN1 on DCs was studied. We found that the expression profiles of circRNAs were significantly different in mature immunogenic DCs v.s immature immunosuppressive DCs. circFSCN1 was the most significantly highly expressed in mature DCs compared with immature DCs. Treatment with immunosuppressive cytokines TGF β and GDF15 reduced circFSCN1 expression in DCs. Knockdown of circFSCN1 using siRNA reduced the phosphorylation of Rel Ap65, but increased phosphorylated Foxo3. Silencing of circFSCN1 impaired DCs to activate T cells, changed inflammatory cytokine production and enhanced Treg generation whereas circFSCN1 siRNA did not affect DC maturation. In conclusion, it is a first report to demonstrate that circFSCN1 is essential for DC immune response.

Effect of TIPE1 on Immune Function of Dendritic Cells and Its Signaling Pathway in Septic Mice.

Dendritic cell (DC) dysfunction plays a pivotal role in sepsis-induced immunosuppression. Tumor necrosis factor α (TNF-α)-induced protein 8 like-1 (TIPE1), a new member of the tumor necrosis factor α-induced protein 8 family, may be related to cell death. The aim of the present study was to elucidate the effect of TIPE1 on the immune function of DCs and its regulatory mechanism via PD-L1/PD-1 signaling in mice. Sepsis was induced in adult C57BL/6 male mice via cecal ligation and puncture. In vitro, we found that expression of CD80, CD86, and major histocompatibility complex class II in DCs and levels of cytokines, including tumor necrosis factor α and interleukin 12p40, were elevated; similarly, T-cell proliferation and differentiation were promoted when the gene expressing TIPE1 was silenced. Next, we examined the in vivo role of TIPE1 in a cecal ligation and puncture animal model system. Flow cytometry of the immune functional status in DCs revealed negative regulation of TIPE1 on DC maturation, as well as activation. Moreover, changes in PD-L1/PD-1 levels confirmed the negative effect of TIPE1 in DCs. Collectively, we report that TIPE1 might exert negative regulation in sepsis, at least in part by inhibiting DC maturation and subsequent T-cell-mediated immunity via PD-L1/PD-1 signaling.

Dendritic Cells in the Host Response to Biomaterials and the Regulatory Pathway

Biomaterial-based strategies can significantly influence the treatment, prevention and diagnosis of multiple diseases. Despite the unprecedented success of biomaterials in addressing unmet biomedical needs and their applicability to personalized medicine, the clinical translation of these biomaterial systems is affected by the limited understanding of their interaction with complex host microenvironments. Biomaterials and biomedical devices implanted in the body may induce a highly complicated and orchestrated series of host responses. As macrophages are among the first cells to infiltrate and respond to implanted biomaterials, the macrophage-mediated host response to biomaterials has been well studied. Dendritic cells (DCs) are the most potent antigen-presenting cells that activate naive T cells and bridge innate and adaptive immunity. The potential interaction of DCs with biomaterials appears to be critical for exerting the function of biomaterials and has become an important, developing area of investigation. Herein, we summarize the effects of the physicochemical properties of biomaterials on the immune function of DCs together with their receptors and signaling pathways. Knowledge of biomaterial-dendritic cell interactions can significantly facilitate clinical translation by guiding the design of biomaterials with particular effects on targeted cells, thus improving their clinical efficacy while minimizing undesired but predictable toxicological effects.

Regulation of Dendritic Cell Immune Function and Metabolism by Cellular Nutrient Sensor Mammalian Target of Rapamycin (mTOR).

Dendritic cell (DC) activation is characterized by an acute increase in glucose metabolic flux that is required to fuel the high anabolic rates associated with DC activation. Inhibition of glycolysis significantly attenuates most aspects of DC immune effector function including antigen presentation, inflammatory cytokine production, and T cell stimulatory capacity. The cellular nutrient sensor mammalian/mechanistic Target of Rapamycin (mTOR) is an important upstream regulator of glycolytic metabolism and plays a central role in coordinating DC metabolic changes and immune responses. Because mTOR signaling can be activated by a variety of immunological stimuli, including signaling through the Toll-like Receptor (TLR) family of receptors, mTOR is involved in orchestrating many aspects of the DC metabolic response to microbial stimuli. It has become increasingly clear that mTOR's role in promoting or attenuating inflammatory processes in DCs is highly context-dependent and varies according to specific cellular subsets and the immunological conditions being studied. This review will address key aspects of the complex role of mTOR in regulating DC metabolism and effector function.