Immune Functions Of Dendritic Cells Research Articles

Total coumarins from Urtica dentata Hand prevent murine autoimmune diabetes via suppression of the TLR4-signaling pathways

Ethnopharmacological relevanceUrtica dentata Hand (UDH), the root of Laportea bulbifera (Sieb. et. Zucc.) Wedd, has been traditionally used in traditional Chinese medicine as an anti-inflammatory and immuno-regulatory agent for rheumatoid arthritis and some other autoimmune diseases treatment. And the coumarins are the major components of UDH. Aim of the studyTo investigate the effect of total coumarins (TC) isolated from UDH on the development of autoimmune diabetes. Materials and methodsEight-week-old non-obese diabetic (NOD) mice were randomly divided into four groups: control group, low-dose (37.5mg/kg), middle-dose (75mg/kg), and high-dose (150mg/kg) TC-treatment groups. NOD mice were then given with a suspension of TC or saline by intragastric (i.g.) administration every other day. After 4 weeks of treatment, 8 mice at 12-weeks of age per group were randomly selected to be sacrificed to perform intraperitoneal glucose tolerance test, examine histopathological insulitis, spleen T lymphocyte proliferation, the percentage of CD4+CD25+Foxp3+ T regulatory cell (Treg), dendritic cell (DC) surface molecules, toll-like receptor (TLR)4 expression and signal pathways involved. The remaining 10 mice per group were kept until 26 weeks of age to assess the incidence of diabetes. We also studied the direct effect of TC on DC and CD4+CD25+ Tregs in vitro. ResultsTreatment with TC for 4 weeks significantly inhibited insulitis, increased pancreatic islet number, delayed the onset and decreased the development of diabetes by 26 weeks of age in NOD mice, compared with the untreated control mice. TC suppressed spleen T lymphocyte proliferation, induced Th2-biased cytokine response, the generation of CD4+CD25+Foxp3+ Tregs and Foxp3 mRNA expression. And TC-treated DCs were characterized as low expression of MHC class II and CD86 molecules. TLR4 gene and protein expressions in the spleen, thymus and pancreas were down-regulated in TC-treated groups. The key molecules in the downstream signaling cascades of TLR4, including myeloid differentiation factor (MyD)88, nuclear factor (NF)-κB, IL-1β, Toll–IL-1 receptor domain-containing adaptor inducing interferon-β(TRIF), TRIF-related adaptor molecule (TRAM), interferon regulatory factor (IRF)-3 and IFN-β, all decreased significantly in TC groups, suggesting that TC inhibits both MyD88-dependent and -independent pathways of TLR4. At the cellular level, however, TLR4 protein expression in DCs, but not in Tregs, was downregulated by TC. And TC strengthened the role of DC, not Treg, in negative immune regulation in vitro. In contrast, anti-TLR4 antibody could block the effect of TC on DCs immune function. ConclusionThese results suggest that TC extracted from UDH prevent the development of autoimmune diabetes in NOD mice via suppression of the TLR4-signaling pathways. TC maintain the DCs in an immature tolerogenic state, at least in part, mediated by down-regulating TLR4-signaling pathways in DCs, then enhance Treg differentiation, shift toward Th2 and suppress T lymphocyte proliferation.

Altered MARCH1 ubiquination-regulated dendritic cell immune functions during the early stage of zymosan-induced multiple organ dysfunction syndrome (MODS) in mice

Using a zymosan-induced mouse model of multiple organ dysfunction syndrome (MODS), we previously found profound increases in spleen immune cells’ expressions of ubiquitin and MHC-II molecules and increased CD11c+ dendritic cells (DCs) within 24h of zymosan injection. We postulated that the early stage of MODS altered DCs function via an ubiquitination-associated mechanism. We intraperitoneally injected zymosan into 100 male C57BL/6 mice (0.8mg/g) and randomly divided them into 5 groups based on the days after injection (20mice/group): 1d, 3d, 5d, 7d, and 10d. Mice were examined for spleen CD11c+ DC functions at the indicated days. Untreated mice were used for normal spleen tissue and T cell samples. By qPCR, IL-12 and TNF-α mRNA expressions in spleen CD11c+ DCs were significantly increased in MODS 1d mice; on subsequent days post-injection, these mRNA levels gradually returned to control levels. The same patterns were found for MODS mice DCs induction of untreated mouse T cells proliferation and IL-2 and IFN-γ mRNA expressions. When T cell functions were examined using MODS 1d DCs with and without MG132 treatment, an inhibitor of ubiquitinated protein degradation, T cell functional activities were enhanced by DCs treated with MG132. MODS 1d DCs also had significantly reduced MARCH1 mRNA expression, a key ubiquitin ligase that regulates DCs MHC-II expression. Silencing DCs MARCH1 expression with siRNA resulted in enhancing their induction of T cell functional activities. Using co-immunoprecipitation, Western blot, and flow cytometry assays, we deduced that MARCH1 ubiquitinated DC surface MHC-II molecules to regulate DC's immune functions in MODS mice. Our results suggest that aberrant degradation of spleen DCs MARCH1-mediated ubiquitinated proteins is involved during the earliest stage of MODS development.

Comparison of effects of fentanyl, sufentanil and remifentanil on immune function of dendritic cells in human umbilical cord blood

Objective To compare the effects of fentanyl,sufentanil and remifentanil on the immune function of dendritic cells in human umbilical cord blood.Methods Human umbilical cord blood mononuclear cells were obtained by density gradient centrifugation and seeded in 24-well plates with a density of 1 × 106/ml (2ml/hole).The cells were randomly divided into 7 groups (n =15 each):control group (group C),fentanyl 1.0 ng/ml group (group F1),fentanyl 5.0 ng/ml group (group F5),sufentanil 0.1 ng/ml group (group S1),sufentanil 0.5 ng/ml group (group S5),remifentanil 1.0 ng/ml group (group R1),and remifentanil 5.0 ng/ml group (group R5).The cells were incubated for 10 days in serum-free culture medium containing 50 ng/ml recombinant human granulocyte colony stimulating factor,10 ng/ml recombinant human interleukin-4 or the corresponding concentration of fentanyl,sufentanil or remifentanil,and then 50 ng/ml recombinant human tumor necrosis factor alpha was added to the culture medium and the cells were incubated for another 4 days in the seven groups.Three holes in each group were chosen and the cell morphology was examined with inverted microscope.Six holes in each group were chosen for determination of the concentration of IL-12 in the supernatant and expression of CD80/CD86.Six holes in each group were chosen for measurement of the cell viability.Results Compared with group C,the concentration of IL-12 and cell viability were significantly decreased and the expression of CD80/CD86 was down-regulated in groups F5,S1,S5,R1 and R5 (P ＜ 0.05).The concentration of IL-12,cell viability and expression of CD80/CD86 were significantly lower in groups S1 and R1 than in group F1 (P ＜ 0.05).Compared with group F5,the concentration of IL-12 was significantly decreased in group S5,and the concentration of IL-12 and cell viability were significantly decreased and the expression of CD80/CD86 was down-regulated in group R5 (P ＜ 0.05).The concentration of IL-12 and cell viability were significantly lower in group R1 than in group S1 (P ＜ 0.05).The concentration of IL-12,cell viability and expression of CD80/CD86 were significantly lower in group R5 than in group S5 (P ＜ 0.05).Conclusion Remifentanil has stronger inhibitory effect on the immunological function of dendritic cells in human umbilical cord blood than sufentanil,and the inhibitory effect of sufentanil is stronger than that of fentanyl. Key words: Fentanyl; Sufentanil; Piperidines; Immunity, cellular; Dendritic cells

Effect of tick saliva on signalling pathways activated by TLR‐2 ligand and Borrelia afzelii in dendritic cells

Dendritic cells are a sentinel in defending against pathogens and tick saliva facilitates transmission of tick-borne pathogens by modulating the host immune response. The maturation of dendritic cells is inhibited by tick saliva. To elucidate the mechanism of this inhibition, we tested the impact of Ixodes ricinus tick saliva on signalling pathways activated by Toll-like receptor (TLR-2) ligand and Borrelia afzelii in spleen dendritic cells. The activation of nuclear factor-κB (NF-κB) p65 and phosphatidylinositol-3 kinase (PI3K)/Akt pathways was decreased by tick saliva upon both TLR-2 and Borrelia stimulation. Among the mitogen-activated protein kinases (MAPK), the activation of extracellular matrix-regulated kinase (Erk1/2) was suppressed by tick saliva, but not p38. In response to spirochaetes, the amount of TNF-α decreased in the presence of tick saliva which was mediated by selective suppression of Erk1/2, NF-κB and Akt as tick saliva mimicked the effect of their specific inhibitors, UO126, IKK-IV and LY294002, respectively. Saliva-induced enhancement of IL-10 was not observed in the presence of specific inhibitor of Protein Kinase A (PKA), H-89, suggesting the involvement of PKA pathway in IL-10 production. Our cumulative data show that tick saliva interferes with several signalling pathways, thus modulating the immune functions of dendritic cells.

Danhong Inhibits Oxidized Low-Density Lipoprotein–Induced Immune Maturation of Dentritic Cells via a Peroxisome Proliferator Activated Receptor γ–Mediated Pathway

Danhong injection (DHI), a Chinese Materia Medica standardized product extracted from Radix Salviae miltiorrhizae and Flos Carthami tinctorii, is effective in the treatment of atherosclerosis (AS)-related diseases. It is widely recognized that AS is a complex inflammatory disease of the arterial wall and the dendritic cells (DCs) is a major player in the pathogenesis of AS via mediating atherosclerotic antigen presenting and T lymphocytes. Here, we determined the effect and possible mechanism of DHI on oxidized low-density lipoprotein (ox-LDL)-induced maturation and immune function of DCs. Human monocyte-derived DCs were incubated with DHI or ciglitazone and were subsequently stimulated with ox-LDL to induce maturation. Similar to ciglitazone, a peroxisome proliferator activated receptor (PPAR) γ agonist, DHI, could significantly reduce ox-LDL-induced expressions of mature markers, enhance the endocytotic function, and inhibit secretions of cytokine on DCs. These effects of DHI could be partly reversed by silencing the PPARγ. In conclusion, DHI could inhibit ox-LDL-induced maturation of DCs partly through activating a PPARγ-mediated signaling pathway.[Supplementary Methods and Figures: available only at http://dx.doi.org/10.1254/jphs.11226FP]

Cowpox virus inhibits human dendritic cell immune function by nonlethal, nonproductive infection

Orthopoxviruses encode multiple proteins that modulate host immune responses. We determined whether cowpox virus (CPXV), a representative orthopoxvirus, modulated innate and acquired immune functions of human primary myeloid DCs and plasmacytoid DCs and monocyte-derived DCs (MDDCs). A CPXV infection of DCs at a multiplicity of infection of 10 was nonproductive, altered cellular morphology, and failed to reduce cell viability. A CPXV infection of DCs did not stimulate cytokine or chemokine secretion directly, but suppressed toll-like receptor (TLR) agonist-induced cytokine secretion and a DC-stimulated mixed leukocyte reaction (MLR). LPS-stimulated NF-κB nuclear translocation and host cytokine gene transcription were suppressed in CPXV-infected MDDCs. Early viral immunomodulatory genes were upregulated in MDDCs, consistent with early DC immunosuppression via synthesis of intracellular viral proteins. We conclude that a nonproductive CPXV infection suppressed DC immune function by synthesizing early intracellular viral proteins that suppressed DC signaling pathways.

Longitudinal tracking of human dendritic cells in murine models using magnetic resonance imaging

Ex vivo generated dendritic cells are currently used to induce therapeutic immunity in solid tumors. Effective immune response requires dendritic cells to home and remain in lymphoid organs to allow for adequate interaction with T lymphocytes. The aim of the current study was to detect and track Feridex labeled human dendritic cells in murine models using magnetic resonance imaging. Human dendritic cells were incubated with Feridex and the effect of labeling on dendritic cells immune function was evaluated. Ex vivo dendritic cell phantoms were used to estimate sensitivity of the magnetic resonance methods and in vivo homing was evaluated after intravenous or subcutaneous injection. R2*-maps of liver, spleen, and draining lymph nodes were obtained and inductively coupled plasma mass spectrometry or relaxometry methods were used to quantify the Feridex tissue concentrations. Correlations between in vivo R2* values and iron content were then determined. Feridex labeling did not affect dendritic cell maturation or function. Phantom results indicated that it was possible to detect 125 dendritic cells within a given slice. Strong correlation between in vivo R2* values and iron deposition was observed. Importantly, Feridex-labeled dendritic cells were detected in the spleen for up to 2 weeks postintravenous injection. This study suggests that magnetic resonance imaging may be used to longitudinally track Feridex-labeled human dendritic cells for up to 2 weeks after injection.

Tongxinluo Inhibits Oxidized Low-density Lipoprotein–induced Maturation of Human Dendritic Cells via Activating Peroxisome Proliferator-Activated Receptor Gamma Pathway

TongXinLuo (TXL) is a traditional Chinese herbal medicine with multiple vasoprotective activities. Dendritic cells (DCs) play an active role in the immunological processes related to atherosclerosis. The purpose of this study was to determine the effect and possible mechanisms of TXL on oxidized low-density lipoprotein (OX-LDL)-induced maturation and immune function of DCs. Human monocyte-derived DCs were incubated with TXL or ciglitazone and were subsequently stimulated with OX-LDL to induce maturation. Similar to ciglitazone, a peroxisome proliferator-activated receptor (PPAR) gamma agonist, TXL could significantly reduce the maturation-associated markers induced by OX-LDL, such as CD40, CD86, CD1a, and human leukocyte antigen-DR; improved the endocytotic function; and decreased secretions of cytokine interleukin-12 and tumor necrosis factor alpha. These inhibitory effects of TXL could be partly reversed by silencing the expression of PPAR gamma in DCs. In conclusion, TXL could inhibit OX-LDL-induced maturation of DCs through activating PPAR gamma pathway.

Association Between High-Mobility Group Box-1 Protein Release and Immune Function of Dendritic Cells in Thermal Injury

The present study was performed to investigate in vivo the effect of high-mobility group box-1 protein (HMGB1) on the maturation of dendritic cell (DC) and the influence on T-cell-mediated immunity after thermal injury. Rats were randomly divided into 3 groups as follows: sham burn group, burn group, and burn with ethyl pyruvate (EP) treatment group, and they were sacrificed on post burn days (PBD) 1, 3, 5, and 7 respectively. MACS microbeads were used to isolate splenic DCs and column of nylon wool to obtain T cells. Phenotypes were analyzed by flow cytometry and cytokines were determined with ELISA kits. The expression levels of splenic HMGB1 were significantly elevated during PBD 1-7. DC expressed similar CD80 levels, strongly enhanced CD86, and slightly elevated MHC class II levels in comparison to DC from sham-injured rats, and protein levels of IL-12 were not increased after thermal injury. Administration of EP to inhibit HMGB1 could significantly enhance expression levels of CD80, MHC class II on DC surface, and IL-12 production after burns. Simultaneously, proliferative activity and expression levels of IL-2 as well as IL-2R alpha of T cell were restored. These results suggested that the excessively released HMGB1 might stimulate splenic DC to mature abnormally and down-regulate the IL-12 production, and further shifting of Th1 to Th2 with suppression of T-lymphocyte immune function following burn injury.

Biomechanical alterations of dendritic cells by co-culturing with K562 CML cells and their potential role in immune escape

Dendritic cells (DCs), which are potent antigen presenting cells (APCs), are utilized to deliver the signals essential for the initiation of immune responses. In this study, we used an interdisciplinary approach to characterize the effect of K562 cells, a human chronic myeloid leukemia (CML) cell line, on the biomechanical characteristics and immune functions of DCs. When co-cultured with K562 cells, the biomechanical and immunological characteristics of immature DCs (imDCs) and mature DCs (mDCs) were severely impaired compared with controls. The changes include increased membrane viscoelasticity, reorganized cytoskeleton (F-actin), suppressed capability of antigen uptake, transendothelium migration, and activation of naïve T cells. In exploring the mechanisms of these changes, we identified several genes and proteins by microarray analysis and 2D gel electrophoresis. Changes were found in the cytoskeleton-related genes and proteins (such as cofilin1 and profilin1) and matrix-related genes and proteins (such as TIMP1 and MMP9). These findings provide a molecular basis for the biomechanical and immunological changes of DCs in response to K562 and may help to elucidate the mechanism for tumor immune escape.

Cross-linking the B7 family molecule B7-DC directly activates immune functions of dendritic cells

Cross-linking the B7 family molecule B7-DC directly activates immune functions of dendritic cells

Pulmonary Orthopoxvirus infection compromises a murine OVA peptide immune response in a dose-dependent manner (39.8)

Abstract Cowpox virus (CPXV), a close relative of variola virus that causes smallpox, can suppress the immune system through a large array of immunosuppressive gene products. We developed a murine model in which DO11.10 T cells specific for an OVA peptide were transferred into BALB/c mice to assess the impact of a pulmonary CPXV infection on DO11.10 T cell proliferation in lung draining lymph nodes following intranasal OVA peptide delivery. High and low-dose CPXV infections were compared. Both doses lead to clinical illness, but the high dose is lethal. A high-dose infection reduced DO11.10 T cell proliferation, but a low-dose infection did not. At the time that proliferation of T cells was assessed (6d),15±1% of lung dendritic cells (DCs) were infected at the high-dose, but only 5±1% of DCs at the low-dose. At both doses, infected and uninfected DCs had decreased expression of co-stimulatory molecules. We speculated that the lung microenvironment created by infection, rather than direct infection of the DCs, suppressed DC immune function. In support, we found that bronchoalveolar lavage fluid and supernatant derived from lung homogenates from infected mice suppressed the function of uninfected lung DCs in vitro. Furthermore, the suppressive activity was more highly concentrated in lungs from high-dose infected mice. These studies strongly suggest that orthopoxvirus infections create an immunosuppressive microenvironment that compromises the host pulmonary immune responses.

Inhibiting effects of total saponins of panax ginseng on immune maturation of dendritic cells induced by oxidized-low density lipoprotein

Total saponins of panax ginseng (TSPG) are the major active components in panax ginseng. Dendritic cells (DCs) play an active role in the immunological processes related to atherosclerosis. The purpose of this study was to determine the effect and possible mechanisms of TSPG on the maturation and immune function of DCs. Compared with those untreated, the DCs pre-treated with TSPG and then induced by oxidized-LDL exhibited a significantly lower expression of the maturation-associated markers of CD40, CD86, HLA-DR, and CD1a, together with an increased endocytosic function as well as decreased secretions of cytokine. However, silencing the expression of PPARγ in DCs, the inhibitory effect of TSPG on the maturation DCs was significantly reduced. In conclusion, TSPG could inhibit the maturation of DCs induced by oxidized-LDL which suggests beneficial effects on atherosclerosis and this effect was partly dependent on the PPARγ pathway at least.

Modification of the innate immune function of dendritic cells by allergen-specific immunotherapy

Modification of the innate immune function of dendritic cells by allergen-specific immunotherapy

Utilizing the FIV model to understand dendritic cell dysfunction and the potential role of dendritic cell immunization in HIV infection

Dendritic cells (DC) are potent antigen presenting cells which initiate and coordinate the immune response making them central targets of and attractive candidates for manipulation in chronic lentiviral infections. Emerging evidence suggests that DC immune function is disrupted during both acute and chronic infection with human immunodeficiency virus (HIV), simian immunodeficiency virus (SIV), and feline immunodeficiency virus (FIV). Despite some early promising data, the use of DC for lentiviral immunotherapy has not fulfilled its expected potential and has been complicated by the large number of variables involved in DC harvesting, purifying, and antigen loading. Pre-clinical studies aimed at identifying successful strategies for DC augmentation of current HIV treatment protocols are needed. Over the past two decades, the FIV model for HIV infection has increased the understanding of retroviral pathogenesis, and studies have begun using the FIV model to study DC dysfunction and DC-mediated immunotherapy. Careful consideration of the many variables involved in DC function and therapy should help develop protocols to explore the potential of DC vaccine-based therapies for lentiviral infection.

Protective effect of epigallocatechin gallate on the immune function of dendritic cells after ultraviolet B irradiation

To investigate the protective effect of epigallocatechin gallate (EGCG) on the immune function of dendritic cells (DCs) after ultraviolet B irradiation (UVB) and its underlying mechanisms. The monocytes were isolated from peripheral blood and cultivated into DCs with cytokines, such as granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4. DCs were harvested after cultivation for 7 days and subjected to irradiation with different dosages of UVB. Then, 200 microg/mL of EGCG was added in certain groups 24 h before irradiation. DCs simply treated with UVB or treated with both UVB and EGCG were co-cultured with lymphocytes, and Mono-nuclear cell direct cytotoxicity (MTT) assay was used to detect the ability of DCs to stimulate proliferation of lymphocytes. Surface markers CD80, CD86, human leukocyte antigen(locus)-DR (HLA-DR), and CD40 were detected using flow cytometry, and the levels of IL-10 and IL-12 secreted from DCs 24 h after cultivation were measured using ELISA. UVB irradiation was able to inhibit the ability of DCs to stimulate the proliferation of lymphocytes and surface expressions of CD80, CD86, HLA-DR, and CD40 on DCs in a dose-dependent manner. The inhibition rate of DCs was improved to some extent after treatment with 200 microg/mL of EGCG. UVB showed no significant influence on the secretion of IL-10 and IL-12 from DCs, while EGCG was able to down-regulate the secretion level of IL-12 and up-regulate that of IL-10. EGCG can antagonize the inhibitory effect on DCs induced by UVB irradiation. This function has some relationship with its protecting effect of the expression of the costimulating molecules on the surface of DCs and the secretion level of IL-10 and IL-12.

Multi-walled carbon nanotubes do not impair immune functions of dendritic cells

The influence of carboxylic multi-walled carbon nanotubes (c-MWCNTs) on the immune activities of dendritic cells (DCs), the most important professional antigen presenting cells, is evaluated. In spite of their diameters, c-MWCNTs are generously phagocytosed by DCs without any cytotoxicity. Treatment with c-MWCNTs, with concentrations of up to 100 μg/mL, does not induce phenotypical maturation of DCs. Furthermore, c-MWCNTs do not interfere with normal DC activation induced by stimulus, such as lipopolysaccharide. The results indicate that c-MWCNTs have good biocompatibility with DCs.

Inhibition of Phenotypic and Functional Maturation of Dendritic Cells by Manassantin A

Manassantin A (MSA) inhibits nitric oxide production by macrophages through the inhibition of NF-κB activation, but the effect of MSA on dendritic cells has not been elucidated yet. Here we investigated the inhibitory effects of MSA on immune functions of dendritic cells (DCs). MSA inhibited lipopolysaccharide (LPS)-induced phenotypic maturation of DCs, which was proved by the decreased expression of CD40, CD80, CD86, MHC-I, and MHC-II. MSA also inhibited functional maturation of DCs, that is, decreased the gene expression of IL-12, IL-1β, TNF-α, and IFN-α/β; enhanced antigen capture capacity of DCs; and impaired induction of allogenic T cell activation. As a mechanism of action, MSA inhibited LPS-induced activation of NF-κB, ERK, p38, and JNK, which played pivotal roles in toll-like receptor 4–mediated DC maturation. Collectively, these results suggested that MSA might be used for the treatment of DC-related immune diseases.

Interactions between osteosarcoma cell lines and dendritic cells immune function: An in vitro study

Dendritic cells (DCs) might be partly responsible for the defective immune response in tumor bearing hosts, but no study in osteosarcoma patients is still available. Therefore, we investigated in vitro whether human osteosarcoma cell lines have an inhibitor effect on different types of DCs: CD14+DCs, DC1 and DC2. DCs derived from healthy donors were cultured with osteosarcoma cell lines and appropriate cytokine cocktails and analysed for the expression of co-stimulatory molecules (CD40, CD80, CD83, CD86, HLA-DR). Each interaction resulted in a lower phenotypic expression of the DCs maturation markers, especially on DC2. Moreover, the addition of various cytokines and compounds (rhIL-12, CD40L, Indometacin) induced the DC1 and DC2 subsets towards the Th1 pattern as shown by ELISA. Osteosarcoma highly interferes with an in vitro DCs immune function as antigen presenting cells. The understanding of tumor biology underlines the need for a specific osteosarcoma immunotherapy able to reverse this immune-surveillance inhibition.

Aberrant Innate Immune Functions of Dendritic Cells in Aged Humans (85.12)

Abstract The molecular mechanisms underlying the chronic inflammation and reduced immunity observed during aging are not well understood. Comparison of the innate immune functions of monocyte-derived DCs from aging subjects with DCs from young individuals showed that MDDCs from aging individuals display significantly reduced capacity to capture antigens via macropinocytosis and receptor-mediated endocytosis as determined by flow cytometry;impaired capacity to migrate in vitro in response to the chemokine MIP3-beta; andsignificantly increased LPS induced secretion of TNF-alpha and IL-6. Investigations of intracellular signaling revealed reduced phosphorylation of AKT in MDDCs from aging, suggesting decreased activation of PI3kinase signaling pathway. Since PI3K signaling pathway plays a positive regulatory role in phagocytosis and migration, and it also functions as a negative regulator of TLR signaling by inducing activation of p38 MAP kinase, this may explain the aberrant innate immune functioning of DCs from aged subjects. Results further revealed an increased expression of PTEN, a negative regulator of PI3Kinase signaling pathway, in MDDCs from aged subjects. Increased PTEN may thus be responsible for the defect in AKT phosphorylation and therefore, altered innate immune response of DCs from aged humans. This study is supported in part by a grant AG027512 from NIH and partly by new scholar grant from the Ellison Medical Foundation.