Single-cell analysis can define distinct evolution of tumor sites in follicular lymphoma

Tumor heterogeneity complicates biomarker development and fosters drug resistance in solid malignancies. In lymphoma, our knowledge of site-to-site heterogeneity and its clinical implications is still limited. Here, we profiled 2 nodal, synchronously acquired tumor samples from 10 patients with follicular lymphoma (FL) using single-cell RNA, B-cell receptor (BCR) and T-cell receptor sequencing, and flow cytometry. By following the rapidly mutating tumor immunoglobulin genes, we discovered that BCR subclones were shared between the 2 tumor sites in some patients, but in many patients, the disease had evolved separately with limited tumor cell migration between the sites. Patients exhibiting divergent BCR evolution also exhibited divergent tumor gene-expression and cell-surface protein profiles. While the overall composition of the tumor microenvironment did not differ significantly between sites, we did detect a specific correlation between site-to-site tumor heterogeneity and T follicular helper (Tfh) cell abundance. We further observed enrichment of particular ligand-receptor pairs between tumor and Tfh cells, including CD40 and CD40LG, and a significant correlation between tumor CD40 expression and Tfh proliferation. Our study may explain discordant responses to systemic therapies, underscores the difficulty of capturing a patient's disease with a single biopsy, and furthers our understanding of tumor-immune networks in FL.

B-cell subsets imbalance and reduced expression of CD40 in ataxia-telangiectasia patients

BACKGROUND

Ataxia-telangiectasia (AT) is a well-known primary immunodeficiency with recurrent sinopulmonary infections and variable abnormalities in both the humoral and cellular immune system. Dysfunctions in immunoglobulin production, reduced number of B cells, and B-cell receptor excision circles copies have been reported. We aimed to understand the immunological mechanisms involving the humoral compartment in AT patients by analysing peripheral blood B cells subsets, B-T lymphocyte cooperation through the expression of CD40 and CD40 ligand (CD40L), and cytokines involved in class-switch recombination production.

METHODS

We compared the proportion of B-cell subsets, the expression of CD40/CD40L, and the plasma levels of IL-6 and IFN-γ of 18 AT patients and 15 healthy age-sex-matched controls using flow cytometry.

RESULTS

We found that some steps in peripheral B cell development were altered in AT with a pronounced reduction of cell-surface CD40 expression. The proportions of transitional and naïve-mature B cells were reduced, whereas CD21-low, natural effector memory, IgM-only memory, and IgG atypical memory B cells were present in a higher proportion.

CONCLUSIONS

These findings revealed a disturbed B-cell homeostasis with unconventional maturation of B lymphocyte memory cells, which can explain the consequent impairment of humoral immunity.

Anti-CD40 antibodies in antiphospholipid syndrome and systemic lupus erythematosus

Anti-β2glycoprotein I (anti-β2GPI) antibodies constitute the main autoantibody specificity in the sera of patients with antiphospholipid syndrome (APS). There is evidence that antiβ2GPI antibodies induce the precoagulant activity of the endothelium by cross-linking the β2 glycoprotein I (β2GPI) on the cell surface. Since β2GPI lacks intracellular domains, homology with other molecules such as CD40 that could initiate signaling, was extensively searched. A 86% homology between the amino acid position 239-245 of the CD40 and 7-13 of the β2glycoprotein was found. The CD40 peptide corresponding to amino acids 239-245 of the CD40 molecule was synthesized and coupled to a multiple antigenic peptide carrier. Antibodies to CD40 peptide were found in 61.5% APS patients (n=39), in 72.7% of systemic lupus erythematosus (SLE) positive for anti β2GPI antibodies (n=11) and 31.6% of SLE negative for antiβ2GPI antibodies (n=19), but not in rheumatoid arthritis patients (n=28) or controls (n=36). Antibodies to CD40 peptide were associated with arterial thrombosis and/or brain microinfarcts. Affinity purified anti-CD40 peptide antibodies as well as affinity purified anti-β2GPI antibodies recognized both, the β2GPI and the CD40 peptide. The specificity of this recognition was confirmed with homologous and heterologous inhibition experiments. Confocal microscopy experiments demonstrated this cross-recognition of CD40 and β2GPI molecules, by the purified anti-CD40 peptide antibodies, at the protein level. Thus, antibodies reacting with the β2GPI can react and potentially activate different cells which express CD40 molecules at their surface.

Clinical significance of costimulatory molecules CD40/CD40L and CD134/CD134L in coronary heart disease: A case-control study

The aim of the study was to evaluate the potential role of CD40/CD40 ligand (CD40L) and CD134/CD134 ligand (CD134L) in the development of coronary heart disease (CHD) via the performance of a case-control study.The research objects were 234 cases of CHD patients and 120 cases of well-matched normal controls. Following the separation of peripheral blood mononuclear cells (PBMCs), real-time quantitative PCR (qRT-PCR), Western blot, immunohistochemistry, and flow cytometry were applied for the detection of mRNA levels and expression levels of CD40/CD40L and CD134/CD134L; meanwhile, intercellular adhesion molecule-1 (ICAM-1) and Fas protein mRNA levels were detected using qRT-PCR.There was no statistical difference in the comparison of baseline characteristics between groups, indicating comparability between groups. qRT-PCR and Western blot analysis indicated that CD40/CD40L and CD134/CD134L mRNA and protein expression levels were all increased in the CHD group than those in the control group. Flow cytometry further confirmed the similar tendency. Meanwhile, ICAM-1 and Fas protein mRNA levels were elevated in the CHD group and positively correlated with the above parameters. Furthermore, CD40/CD40L expression rates were negatively correlated with gender and different types of CHD. Meanwhile, CD134/CD134L expressions were also higher in male patients, in patients with family history, previous history of hypertension, diabetes, and cerebrovascular diseases.CD40/CD40L and CD134/CD134L are increased and may have potential correlation with clinical pathological features of patients with CHD. Further in-depth exploration of costimulatory molecules for CHD guidance as well as intrinsic mechanisms are needed combined with in vivo and in vitro experiments.

Three-dimensional spheroid cell model of in vitro adipocyte inflammation

To improve treatment of obesity, a contributing factor to multiple systemic and metabolic diseases, a better understanding of metabolic state and environmental stress at the cellular level is essential. This work presents development of a three-dimensional (3D) in vitro model of adipose tissue displaying induced lipid accumulation as a function of fatty acid supplementation that, subsequently, investigates cellular responses to a pro-inflammatory stimulus, thereby recapitulating key stages of obesity progression. Three-dimensional spheroid organization of adipose cells was induced by culturing 3T3-L1 mouse preadipocytes on an elastin-like polypeptide-polyethyleneimine (ELP-PEI)-coated surface. Results indicate a more differentiated phenotype in 3D spheroid cultures relative to two-dimensional (2D) monolayer analogues based on triglyceride accumulation, CD36 and CD40 protein expression, and peroxisome proliferator-activated receptor-γ (PPAR-γ) and adiponectin mRNA expression. The 3T3-L1 adipocyte spheroid model was then used to test the effects of a pro-inflammatory microenvironment, namely maturation in the presence of elevated fatty acid levels followed by acute exposure to tumor necrosis factor alpha (TNF-α). Under these conditions, we demonstrate that metabolic function was reduced across all cultures exposed to TNF-α, especially so when pre-exposed to linoleic acid. Further, in response to TNF-α, enhanced lipolysis, monitored as increased extracellular glycerol and fatty acids levels, was observed in adipocytes cultured in the presence of exogenous fatty acids. Taken together, our 3D spheroid model showed enhanced adipogenic differentiation and presents a platform for elucidating the key phenotypic responses that occur in pro-inflammatory microenvironments that characterize obesogenic states.

Galectin-2 induces a proinflammatory, anti-arteriogenic phenotype in monocytes and macrophages

Galectin-2 is a monocyte-expressed carbohydrate-binding lectin, for which increased expression is genetically determined and associated with decreased collateral arteriogenesis in obstructive coronary artery disease patients. The inhibiting effect of galectin-2 on arteriogenesis was confirmed in vivo, but the mechanism is largely unknown. In this study we aimed to explore the effects of galectin-2 on monocyte/macrophage phenotype in vitro and vivo, and to identify the receptor by which galectin-2 exerts these effects. We now show that the binding of galectin-2 to different circulating human monocyte subsets is dependent on monocyte surface expression levels of CD14. The high affinity binding is blocked by an anti-CD14 antibody but not by carbohydrates, indicating a specific protein-protein interaction. Galectin-2 binding to human monocytes modulated their transcriptome by inducing proinflammatory cytokines and inhibiting pro-arteriogenic factors, while attenuating monocyte migration. Using specific knock-out mice, we show that galectin-2 acts through the CD14/toll-like receptor (TLR)-4 pathway. Furthermore, galectin-2 skews human macrophages to a M1-like proinflammatory phenotype, characterized by a reduced motility and expression of an anti-arteriogenic cytokine/growth factor repertoire. This is accompanied by a switch in surface protein expression to CD40-high and CD206-low (M1). In a murine model we show that galectin-2 administration, known to attenuate arteriogenesis, leads to increased numbers of CD40-positive (M1) and reduced numbers of CD206-positive (M2) macrophages surrounding actively remodeling collateral arteries. In conclusion galectin-2 is the first endogenous CD14/TLR4 ligand that induces a proinflammatory, non-arteriogenic phenotype in monocytes/macrophages. Interference with CD14-Galectin-2 interaction may provide a new intervention strategy to stimulate growth of collateral arteries in genetically compromised cardiovascular patients.

Clinical and biological effects of an agonist anti-CD40 antibody: a Cancer Research UK phase I study

PURPOSE

This phase I study aimed to establish the biologic effects and MTD of the agonistic IgG1 chimeric anti-CD40 antibody ChiLob7/4 in patients (pts) with a range of CD40-expressing solid tumors and diffuse large B-cell lymphoma, resistant to conventional therapy. Potential mechanisms of action for agonistic anti-CD40 include direct cytotoxic effects on tumor cells and conditioning of antigen-presenting cells.

EXPERIMENTAL DESIGN

ChiLob7/4 was given by IV infusion weekly for 4 doses at a range from 0.5 to 240 mg/dose. Validated ELISAs were used to quantify ChiLob7/4 in serum and test for anti-chimeric MAb (HACA) responses. Pharmacodynamic assessments included quantitation of T-cell, natural killer-cell, and B-cell numbers and activation in blood by flow cytometry and a panel of cytokines in plasma by Luminex technology. Planned dose escalation was in cohorts of 3 patients until MTD or biologic effect, defined as reduction of peripheral blood CD19(+) B cells to 10% or less of baseline.

RESULTS

Twenty-nine courses of treatment were given to 28 subjects. The MTD was 200 mg × 4, with dose-limiting toxicity of liver transaminase elevations at 240 mg. At 200 mg (range between 2.1 mg/kg and 3.3 mg/kg based on patient body weight), the trough level pretreatment was above 25 μg/mL. Grade 1-2 infusion reactions were seen above the dose of 16 mg, but could be prevented with single-dose corticosteroid premedication. HACA responses were seen after doses between 1.6 mg and 50 mg, but not above this. There were dose-dependent falls in blood B-cell numbers accompanied by reduced expression of CD21, and transient reductions in NK cell numbers with increased CD54 expression from 50 mg upward. MIP-1β and IL12 plasma concentrations rose after doses above 16 mg. Fifteen of 29 treatments were accompanied by disease stabilization for a median 6 months, the longest for 37 months.

CONCLUSIONS

ChiLob7/4 can activate B and NK cells at doses that can be administered safely, and should be tested in combination with other antibodies and chemotherapy agents.

p38 Mitogen-Activated Protein Kinase in beryllium-induced dendritic cell activation

Dendritic cells (DC) play a role in the regulation of immune responses to haptens, which in turn impact DC maturation. Whether beryllium (Be) is able to induce DC maturation and if this occurs via the MAPK pathway is not known. Primary monocyte-derived DCs (moDCs) models were generated from Be non-exposed healthy volunteers as a non-sensitized cell model, while PBMCs from BeS (Be sensitized) and CBD (chronic beryllium disease) were used as disease models. The response of these cells to Be was evaluated. The expression of CD40 was increased significantly (p<0.05) on HLA-DP Glu69+ moDCs after 100 μM BeSO₄-stimulation. BeSO₄ induced p38MAPK phosphorylation, while IκB-α was degraded in Be-stimulated moDCs. The p38 MAPK inhibitor SB203580 blocked Be-induced NF-κB activation in moDCs, suggesting that p38MAPK and NF-κB are dependently activated by BeSO₄. Furthermore, in BeS and CBD subjects, SB203580 downregulated Be-stimulated proliferation in a dose-dependent manner, and decreased Be-stimulated TNF-α and IFNγ cytokine production. Taken together, this study suggests that Be-induces non-sensitized Glu69+ DCs maturation, and that p38MAPK signaling is important in the Be-stimulated DCs activation as well as subsequent T cell proliferation and cytokine production in BeS and CBD. In total, the MAPK pathway may serve as a potential therapeutic target for human granulomatous lung diseases.

PP4 is essential for germinal center formation and class switch recombination in mice

PP4 is a serine/threonine phosphatase required for immunoglobulin (Ig) VDJ recombination and pro-B/pre-B cell development in mice. To elucidate the role of PP4 in mature B cells, we ablated the catalytic subunit of murine PP4 invivo utilizing the CD23 promoter and cre-loxP recombination and generated CD23^crePP4^F/F mice. The development of follicular and marginal zone B cells was unaffected in these mutants, but the proliferation of mature PP4-deficient B cells stimulated by invitro treatment with either anti-IgM antibody (Ab) or LPS was partially impaired. Interestingly, the induction of CD80 and CD86 expression on these stimulated B cells was normal. Basal levels of serum Igs of all isotypes were strongly reduced in CD23^crePP4^F/F mice, and their B cells showed a reduced efficiency of class switch recombination (CSR) invitro upon stimulation by LPS or LPS plus IL-4. When CD23^crePP4^F/F mice were challenged with either the T cell-dependent antigen TNP-KLH or the T cell-independent antigen TNP-Ficoll, or by H1N1 virus infection, the mutant animals failed to form germinal centers (GCs) in the spleen and the draining mediastinal lymph nodes, and did not efficiently mount antigen-specific humoral responses. In the resting state, PP4-deficient B cells exhibited pre-existing DNA fragmentation. Upon stimulation by DNA-damaging drug etoposide invitro, mutant B cells showed increased cleavage of caspase 3. In addition, the mutant B cells displayed impaired CD40-mediated MAPK activation, abnormal IgM-mediated NF-κB activation, and reduced S phase entry upon IgM/CD40-stimulation. Taken together, our results establish a novel role for PP4 in CSR, and reveal crucial functions for PP4 in the maintenance of genomic stability, GC formation, and B cell-mediated immune responses.

DCs sensitized with mPD-L1-Ig fusion protein improve the effect of heart transplantation in mice by promoting the generation of T-reg cells

PURPOSE

To detect the effects of DCs sensitized by mPD-L1-Ig fusion protein in heart transplantation in mice as well as its mechanisms.

METHOD

The mPD-L1-IgG1 construct was used to build a yeast expression system, and the fusion protein was expressed by secretion after the transfection of the GS115 yeast strain, purified by affinity chromatography and ion exchange chromatography, and assayed by SDS-PAGE and Western blot. The ability of the fusion protein to bind to the acceptor PD-1 was tested by ELISA, and the ability of the fusion protein to inhibit the function of T cells was tested by mixed lymphocyte reaction (MLR).

RESULTS

We used the new PD-L1-IgG1 fusion protein to sensitize imDCs and maintained the immature state of DCs, so as to induce stable and effective immune tolerance to heart transplantation. After the treatment of DCs by mPD-L1-Ig in vitro, the levels of CD80, CD40 and I-Ab expression on DCs are relatively weaker, the ability of DCs to stimulates the proliferation of allogeneic spleen T cells was significantly decreased (P<0.01), and the levels of Th1 (IL-2, IFN-γ) and Th2 (IL-4, IL-10) secreted by induced allogeneic T cells were significantly decreased (P<0.01). An in vivo experiment also revealed that DCs sensitized by mPD-L1-IgG1 could prolong the survival time of a transplanted heart to 17.8±1.12days, and alleviate the pathological change of the cardiac allografts compared with other three groups.

CONCLUSION

DCs sensitized by the yeast-expressed mPD-L1-Ig fusion protein are shown to alleviate the cardiac allograft rejection in mice.

Inhibitory effects of neural stem cells derived from human embryonic stem cells on differentiation and function of monocyte-derived dendritic cells

Neural stem cells (NSCs) possess immunosuppressive characteristics, but effects of NSCs on human dendritic cells (DCs), the most important antigen presenting cells, are less well studied. We used an in vitro approach to evaluate the effects of human NSCs on differentiation of human blood CD14(+) monocytes into DCs. NSCs derived from H1 human embryonic stem cells (hESC-NSCs) and human ReNcell NSC line, as well as human bone marrow derived mesenchymal stem cells (MSCs), were tested. We observed that in response to treatment with interleukin-4 and granulocyte macrophage colony-stimulating factor CD14(+) monocytes co-cultured with NSCs were able to down-regulate CD14 and up-regulate the differentiation marker CD1a, whereas MSC co-culture strongly inhibited CD1a expression and supported prolonged expression of CD14. A similar difference between NSCs and MSCs was noted when lipopolysaccharides were included to induce maturation of monocyte-derived DCs. However, when effects on the function of derived DCs were investigated, NSCs suppressed the elevation of the DC maturation marker CD83, although not the up-regulation of costimulatory molecules CD80, CD86 and CD40, and impaired the functional capacity of the derived DCs to stimulate alloreactive T cells. We did not observe any obvious difference between hESC-NSCs and ReNcell NSCs in inhibiting DC maturation and function. Our data suggest that although human NSCs are less effective than human MSCs in suppressing monocyte differentiation into DCs, these stem cells can still affect the function of DCs, ultimately regulating specific immune responses.

Inhibition of both BRAF and MEK in BRAF(V600E) mutant melanoma restores compromised dendritic cell (DC) function while having differential direct effects on DC properties

PURPOSE

Dendritic cells (DCs) can induce strong tumor-specific T-cell immune responses. Constitutive upregulation of the mitogen-activated protein kinase (MAPK) pathway by a BRAF(V600) mutation, which is present in about 50 % of metastatic melanomas, may be linked to compromised function of DCs in the tumor microenvironment. Targeting both MEK and BRAF has shown efficacy in BRAF(V600) mutant melanoma.

METHODS

We co-cultured monocyte-derived human DCs with melanoma cell lines pretreated with the MEK inhibitor U0126 or the BRAF inhibitor vemurafenib. Cytokine production (IL-12 and TNF-α) and surface marker expression (CD80, CD83, and CD86) in DCs matured with the Toll-like receptor 3/Melanoma Differentiation-Associated protein 5 agonist polyI:C was examined. Additionally, DC function, viability, and T-cell priming capacity were assessed upon direct exposure to U0126 and vemurafenib.

RESULTS

Cytokine production and co-stimulation marker expression were suppressed in polyI:C-matured DCs exposed to melanoma cells in co-cultures. This suppression was reversed by MAPK blockade with U0126 and/or vemurafenib only in melanoma cell lines carrying a BRAF(V600E) mutation. Furthermore, when testing the effect of U0126 directly on DCs, marked inhibition of function, viability, and DC priming capacity was observed. In contrast, vemurafenib had no effect on DC function across a wide range of dose concentrations.

CONCLUSIONS

BRAF(V600E) mutant melanoma cells modulate DC through the MAPK pathway as its blockade can reverse suppression of DC function. MEK inhibition negatively impacts DC function and viability if applied directly. In contrast, vemurafenib does not have detrimental effects on important functions of DCs and may therefore be a superior candidate for combination immunotherapy approaches in melanoma patients.

CD40L--a costimulatory molecule involved in the maturation of antigen presenting cells in Atlantic salmon (Salmo salar)

The CD40L/CD40 signalling pathway is critically involved in the final stage of the maturation of DCs. This paper reports the identification and functional characterization of CD40L and CD40 from Atlantic salmon (Salmo salar). Salmon CD40L is a type II membrane-bound protein with a TNF homology domain in its extracellular C-terminal region, while CD40 is a type I membrane-bound receptor with a sequence pattern of four cysteine-rich domains in its extracellular N-terminal region. The salmon CD40L and CD40 were widely expressed, particularly in immune tissues, and while CD40L expression was induced by in vitro stimulation of HKLs with PHA and ConA, CpG increased CD40 expression. A CD40L construct was overexpressed in the CHSE-214 cell line and co-cultivation of the CD40L-CHSE transfectants with HKL induced a rapid and long-lasting upregulation of important costimulatory molecules like CD40, CD83, B7-H1 and the cytokines IL-12p40, IL-10, IL-1β and IFNs, which all are involved in T-helper cell responses. Furthermore, the CD40L transfected cells increased the percentage of HKLs expressing surface MHCIIβ but unlike other APC maturation stimuli, like CpG, they did not reduce the capacity to internalise antigen. Our results provide the first evidence for the existence of a functional CD40L mediated costimulatory pathway in Atlantic salmon.

Expression of CD40 and growth-inhibitory activity of CD40 agonist in ovarian carcinoma cells

The CD40 receptor is a member of the tumour necrosis factor receptor family and is widely expressed on various cell types. The antitumour activity of CD40 agonist antibody has been observed in B-cell-derived malignancies, but its activity on ovarian cancer remains unclear. However, in this paper, we first confirmed that the anti-CD40 agonist antibody could inhibit the growth of ovarian cancer cells and induce apoptosis. This study investigated the expression of CD40 by ovarian carcinoma tissues and cell lines, at the same time, we evaluated the effect of a recombinant soluble human CD40L (rshCD40L) and an anti-CD40 agonist antibody on cell growth and apoptosis. Flow cytometry and immunohistochemistry assay demonstrated that CD40 was expressed on ovarian carcinoma cell lines and primary ovarian carcinoma cells derived from ascites, as well as on ovarian carcinoma tissues. The growth inhibition of rshCD40L and the anti-CD40 agonist antibody on ovarian carcinoma cells was examined by MTT assay, and the proportion of apoptotic tumour cells was analysed by flow cytometry and Hoechst staining. Our study showed that CD40 was expressed on all ovarian carcinoma cell lines and was examined in 86.2% (162/188) of ovarian cancer tissue samples, but not in normal ovarian tissues (n = 20). Treatment with rshCD40L or anti-CD40 agonist antibody significantly inhibited ovarian carcinoma cell growth and induced apoptosis. Theses results suggest that CD40 is expressed on ovarian carcinoma cells, moreover, that rshCD40L and anti-CD40 agonist antibody have therapeutic potential to inhibit human ovarian cancer growth.

Trophoblast cells induce a tolerogenic profile in dendritic cells

BACKGROUND

Dendritic cells (DCs), which are biased toward a tolerogenic profile, play a pivotal role in tissue-remodeling processes and angiogenesis at the maternal-fetal interface. Here, we analyzed the effect of trophoblast cells on the functional profile of DCs to gain insight on the tolerogenic mechanisms underlying the human placental-maternal dialog at early stages of gestation.

METHODS

DCs were differentiated from peripheral blood monocytes obtained from fertile women (n = 21), in the presence of interleukin (IL)-4 and granulocyte-macrophage colony-stimulating factor during 5 days in culture. Then, DCs were cultured with trophoblast cells (Swan-71 cell line obtained from normal cytotrophoblast, at 7 weeks) for 24 h and for an additional 24 h in the absence or presence of lipopolysaccharide (LPS) from Escherichia coli. DCs were recovered and used for flow cytometry, enzyme-linked immunosorbent assay, RT-PCR and suppression and migration assays.

RESULTS

Trophoblast cells significantly prevented the increase in CD83 expression induced by LPS without affecting the expression of CD86, CD40 and human leukocyte antigen-DR (P < 0.05). Trophoblast cells significantly decreased the production of IL-12p70 and tumor necrosis factor-α, while it increased the production of IL-10 (P < 0.05). No changes were observed in the production of IL-6 and monocyte chemotactic protein-1. The culture of DCs with trophoblast cells, also suppressed the stimulation of the allogeneic response triggered by LPS (P < 0.05). Conditioned DCs were able to increase the frequency of CD4 + CD25 + Foxp3 cells and this effect was accompanied by an increase in indoleamine 2, 3-dioxygenase expression in DCs (P < 0.05).

CONCLUSIONS

The interaction of DCs with trophoblast cells promotes the differentiation of DCs into cells with a predominantly tolerogenic profile that could contribute to a tolerogenic microenvironment at the maternal-fetal interface.

Prevention of autoimmune diabetes and induction of β-cell proliferation in NOD mice by hyperbaric oxygen therapy

We evaluated the effects of hyperbaric oxygen therapy (HOT) on autoimmune diabetes development in nonobese diabetic (NOD) mice. Animals received no treatment or daily 60-min HOT 100% oxygen (HOT-100%) at 2.0 atmospheres absolute and were monitored for diabetes onset, insulitis, infiltrating cells, immune cell function, and β-cell apoptosis and proliferation. Cyclophosphamide-induced diabetes onset was reduced from 85.3% in controls to 48% after HOT-100% (P < 0.005) and paralleled by lower insulitis. Spontaneous diabetes incidence reduced from 85% in controls to 65% in HOT-100% (P = 0.01). Prediabetic mice receiving HOT-100% showed lower insulitis scores, reduced T-cell proliferation upon stimulation in vitro (P < 0.03), increased CD62L expression in T cells (P < 0.04), reduced costimulation markers (CD40, DC80, and CD86), and reduced major histocompatibility complex class II expression in dendritic cells (DCs) (P < 0.025), compared with controls. After autoimmunity was established, HOT was less effective. HOT-100% yielded reduced apoptosis (transferase-mediated dUTP nick-end labeling-positive insulin-positive cells; P < 0.01) and increased proliferation (bromodeoxyuridine incorporation; P < 0.001) of insulin-positive cells compared with controls. HOT reduces autoimmune diabetes incidence in NOD mice via increased resting T cells and reduced activation of DCs with preservation of β-cell mass resulting from decreased apoptosis and increased proliferation. The safety profile and noninvasiveness makes HOT an appealing adjuvant therapy for diabetes prevention and intervention trials.

Mechanisms underlying sCD40 production in hemodialysis patients

CD40 and its ligand (CD40L) regulate several cellular functions, including T and B-cell activation. The soluble form of CD40 (sCD40) antagonizes CD40/CD40L interaction. Patients undergoing hemodialysis (HD) present elevated sCD40 serum levels, which underlying molecular mechanisms are unknown. We studied sCD40 serum and urinary levels, CD40 membrane and gene expression and membrane shedding in HD, uremic not-HD patients (UR) and healthy subjects (N). We found that in HD sCD40 serum levels were higher than UR and N, being significantly elevated in anuric patients, and that sCD40 correlated to renal function in UR subjects, who presented also a reduced sCD40 urinary excretion rate. HD and UR presented reduced CD40 membrane and gene expression. The concentration of TNF-α converting enzyme (TACE), responsible for CD40 cleavage was not different between HD and N. Therefore the reduced renal clearance is the main cause of elevated sCD40 levels in HD. This finding could have relevant clinical implications.

Activation of cord blood myeloid dendritic cells by Trypanosoma cruzi and parasite-specific antibodies, proliferation of CD8+ T cells, and production of IFN-γ

We previously reported that Trypanosoma cruzi, the agent of Chagas disease, induces in congenitally infected fetuses a strong, adult-like parasite-specific CD8(+) T cell response producing IFN-γ (Hermann et al. in Blood 100:2153-2158, 2002). This suggests that the parasite is able to overcome the immaturity of neonatal antigen presenting cells, an issue which has not been previously addressed. We therefore investigated in vitro the ability of T. cruzi to activate cord blood DCs and compared its effect to that on adult cells. We show that T. cruzi induces phenotypic maturation of cord blood CD11c(+) myeloid DCs (mDCs), by enhancing surface expression of CD40, CD80, and CD83, and that parasite-specific IgG purified from cord blood of neonates born to T. cruzi-infected mothers amplify such expression. CD83, considered as the best marker of mature DCs, reaches higher level on cord blood than on adult mDCs. Allo-stimulation experiments showed that T. cruzi-activated cord blood mononuclear cells enriched in DCs (eDCs) stimulate proliferation of cord blood and adult CD3(+) T cells to a similar extent. Of note, T. cruzi-activated eDCs from cord blood trigger more potent proliferation of CD8(+) than CD8(-) (mainly CD4(+)) adult T cells, a feature not observed with adult eDCs. T cell proliferation is associated with IFN-γ release and down-regulation of IL-13 production. These data show that T. cruzi potently activates human cord blood mDCs and endows eDCs to trigger CD8(+) T cell proliferation and favor type 1 immune response. Interestingly, maternal antibodies can strengthen the development of mature DCs that might contribute to overcome the immunological immaturity associated with early life.

Preeclampsia serum upregulates CD40/CD40L expression and induces apoptosis in human umbilical cord endothelial cells

BACKGROUND

The endothelial cell dysfunction observed in preeclampsia (PE) may be induced by CD40/CD40L signaling. This study investigated the role of CD40/CD40L in the pathogenesis of PE by comparing the effect of maternal serum obtained from healthy pregnant women and PE patients on HUVEC cell growth, apoptosis and CD40/CD40L expression.

METHODS

Maternal serum was obtained from 20 patients with PE (PE group) as well as 20 healthy pregnant women (control group). The human umbilical endothelial cell line, CRL1730, was cultured in the presence of maternal serum for 24, 48, and 72 h after which cell growth and apoptosis were assessed by MTT and flow cytometry analysis, respectively. CD40/CD40L expression was determined using flow cytometry and RT-PCR analyses.

RESULTS

As compared to CRL1730 cells treated with control sera, those treated with PE sera had altered morphology, decreased cell growth, increased apoptosis and greater CD40/CD40L protein and mRNA expression. Stimulation of CD40/CD40L protein and mRNA expression by PE sera was greatest at 24 h.

CONCLUSIONS

PE sera may induce endothelial cell damage possibly through increased CD40/CD40L expression in early-onset PE. Further studies are necessary to determine the factor(s) in PE sera responsible for the observed changes in endothelial cell viability.

Antigen-specific induced Foxp3+ regulatory T cells are generated following CD40/CD154 blockade

Blockade of the CD40/CD154 pathway potently attenuates T-cell responses in models of autoimmunity, inflammation, and transplantation. Indeed, CD40 pathway blockade remains one of the most powerful methods of prolonging graft survival in models of transplantation. But despite this effectiveness, the cellular and molecular mechanisms underlying the protective effects of CD40 pathway blockade are incompletely understood. Furthermore, the relative contributions of deletion, anergy, and regulation have not been measured in a model in which donor-reactive CD4(+) and CD8(+) T-cell responses can be assessed simultaneously. To investigate the impact of CD40/CD154 pathway blockade on graft-specific T-cell responses, a transgenic mouse model was used in which recipients containing ovalbumin-specific CD4(+) and CD8(+) TCR transgenic T cells were grafted with skin expressing ovalbumin in the presence or absence of anti-CD154 and donor-specific transfusion. The results indicated that CD154 blockade altered the kinetics of donor-reactive CD8(+) T-cell expansion, delaying differentiation into IFN-γ(+) TNF(+) multifunctional cytokine producers. The eventual differentiation of cytokine-producing effectors in tolerant animals coincided with the emergence of an antigen-specific CD4(+) CD25(hi) Foxp3(+) T-cell population, which did not arise from endogenous natural T(reg) but rather were peripherally generated from naïve Foxp3(-) precursors.

Nuclear factor-κB2 represses Sp1-mediated transcription at the CD99 promoter

Downregulation of the CD99 antigen on the surface of Hodgkin's lymphoma (HL) cells via EBV LMP1-mediated NF-κB suppression of Sp1 transcriptional activity is known to be associated with the appearance of pathogenic Reed-Sternberg cells. Here, we show that in addition, EBV LMP1 heterologous NF-κB activators such as CD30 and CD40 repress the CD99 promoter, which contains multiple Sp1-binding sites but no NF-κB binding sites. In addition, NF-κB-inducing kinase (NIK) repressed the CD99 promoter while NIK kinase mutants and JNK inhibitory protein failed to do so. Of the NF-κB subunits, NF-κB2 (p52) alone or in combination with other Rel subunits consistently inhibited the CD99, while NF-κB1 (p50) showed a marginal repressive effect. Furthermore, while transfection of LMP1 repressed the CD99 promoter in wild-type or NF-κB1 deficient MEFs, the same repression was not observed in NF-κB2 (p52)-deficient MEFs, indicating that NF-κB2 (p52) is required for LMP1-mediated repression of the CD99 promoter. Consistently, basal activity of the CD99 promoter was significantly higher in IKKα(-/-) and IKKβ(-/-) MEFs, but not in IKKΓ(-/-) MEFs compared to the wild-type control MEFs. Sp1-binding sites were directly used in the repression, because a synthetic Sp1 reporter with 10 Sp1-binding sites from the CD99 promoter was repressed by LMP1 or p52 transfection. These data indicate that LMP1-mediated NF-κB2 exhibits the major inhibitory role in the transcription at the CD99 promoter.

Functional activation of T cells by dendritic cells and macrophages exposed to the intracellular parasite Neospora caninum

Neospora caninum is an intracellular protozoan pathogen that causes abortion in cattle. We studied how the interaction between murine conventional dendritic cells or macrophages and N. caninum influences the generation of cell-mediated immunity against the parasite. We first explored the invasion and survival ability of N. caninum in dendritic cells and macrophages. We observed that protozoa rapidly invaded and proliferated into these two cell populations. We then investigated how Neospora-exposed macrophages or dendritic cells distinguish between viable and non-viable (heat-killed tachyzoites and antigenic extract) parasites. Viable tachyzoites and antigenic extract, but not killed parasites, altered the phenotype of immature dendritic cells. Dendritic cells infected with viable parasites down-regulated the expression of MHC-II, CD40, CD80 and CD86 whereas dendritic cells exposed to N. caninum antigenic extract up-regulated the expression of MHC-II and CD40 and down-regulated CD80 and CD86 expression. Moreover, only viable tachyzoites and antigenic extract induced IL-12 synthesis by dendritic cells. MHC-II expression was up-regulated and CD86 expression was down-regulated at the surface of macrophages, regardless of the parasitic form was encountered. However, IL-12 secretion by macrophages was only observed under conditions using viable and heat-killed parasite. We then analysed how macrophages and dendritic cells were involved in inducing T-cell responses. T lymphocyte IFN-γ-secretion in correlation with IL-12 production occurred after interactions between T cells and dendritic cells exposed to viable tachyzoites or antigenic extract. By contrast, for macrophages IFN-γ production was IL-12-independent and only occurred after interactions between T cells and macrophages exposed to antigenic extract. Thus, N. caninum-induced activation of murine dendritic cells, but not that of macrophages, was associated with T cell IFN-γ production after IL-12 secretion.

The CD40-autophagy pathway is needed for host protection despite IFN-Γ-dependent immunity and CD40 induces autophagy via control of P21 levels

Autophagy degrades pathogens in vitro. The autophagy gene Atg5 has been reported to be required for IFN-γ-dependent host protection in vivo. However, these protective effects occur independently of autophagosome formation. Thus, the in vivo role of classic autophagy in protection conferred by adaptive immunity and how adaptive immunity triggers autophagy are incompletely understood. Employing biochemical, genetic and morphological studies, we found that CD40 upregulates the autophagy molecule Beclin 1 in microglia and triggers killing of Toxoplasma gondii dependent on the autophagy machinery. Infected CD40(-/-) mice failed to upregulate Beclin 1 in microglia/macrophages in vivo. Autophagy-deficient Beclin 1(+/-) mice, mice with deficiency of the autophagy protein Atg7 targeted to microglia/macrophages as well as CD40(-/-) mice exhibited impaired killing of T. gondii and were susceptible to cerebral and ocular toxoplasmosis. Susceptibility to toxoplasmosis occurred despite upregulation of IFN-γ, TNF-α and NOS2, preservation of IFN-γ-induced microglia/macrophage anti-T. gondii activity and the generation of anti-T. gondii T cell immunity. CD40 upregulated Beclin 1 and triggered killing of T. gondii by decreasing protein levels of p21, a molecule that degrades Beclin 1. These studies identified CD40-p21-Beclin 1 as a pathway by which adaptive immunity stimulates autophagy. In addition, they support that autophagy is a mechanism through which CD40-dependent immunity mediates in vivo protection and that the CD40-autophagic machinery is needed for host resistance despite IFN-γ.

Detailed kinetics of the direct allo-response in human liver transplant recipients: new insights from an optimized assay

Conventional assays for quantification of allo-reactive T-cell precursor frequencies (PF) are relatively insensitive. We present a robust assay for quantification of PF of T-cells with direct donor-specificity, and establish the kinetics of circulating donor-specific T cells after liver transplantation (LTx). B cells from donor splenocytes were differentiated into professional antigen-presenting cells by CD40-engagement (CD40-B cells). CFSE-labelled PBMC from LTx-recipients obtained before and at several time points after LTx, were stimulated with donor-derived or 3rd party CD40-B cells. PF of donor-specific T cells were calculated from CFSE-dilution patterns, and intracellular IFN-γ was determined after re-stimulation with CD40-B cells. Compared to splenocytes, stimulations with CD40-B cells resulted in 3 to 5-fold higher responding T-cell PF. Memory and naïve T-cell subsets responded equally to allogeneic CD40-B cell stimulation. Donor-specific CD4+ and CD8+ T-cell PF ranged from 0.5 to 19% (median: 5.2%). One week after LTx, PF of circulating donor-specific CD4+ and CD8+ T cells increased significantly, while only a minor increase in numbers of T cells reacting to 3rd party allo-antigens was observed. One year after LTx numbers of CD4+ and CD8+ T cells reacting to donor antigens, as well as those reacting to 3rd party allo-antigens, were slightly lower compared to pre-transplant values. Moreover, CD4+ and CD8+ T cells responding to donor-derived, as well as those reacting to 3rd party CD40-B cells, produced less IFN-γ. In conclusion, our alternative approach enables detection of allo-reactive human T cells at high frequencies, and after application we conclude that donor-specific T-cell PF increase immediately after LTx. However, no evidence for a specific loss of circulating T-cells recognizing donor allo-antigens via the direct pathway up to 1 year after LTx was obtained, underscoring the relative insensitiveness of previous assays.

A method for generation of bone marrow-derived macrophages from cryopreserved mouse bone marrow cells

The broad use of transgenic and gene-targeted mice has established bone marrow-derived macrophages (BMDM) as important mammalian host cells for investigation of the macrophages biology. Over the last decade, extensive research has been done to determine how to freeze and store viable hematopoietic human cells; however, there is no information regarding generation of BMDM from frozen murine bone marrow (BM) cells. Here, we establish a highly efficient protocol to freeze murine BM cells and further generate BMDM. Cryopreserved murine BM cells maintain their potential for BMDM differentiation for more than 6 years. We compared BMDM obtained from fresh and frozen BM cells and found that both are similarly able to trigger the expression of CD80 and CD86 in response to LPS or infection with the intracellular bacteria Legionella pneumophila. Additionally, BMDM obtained from fresh or frozen BM cells equally restrict or support the intracellular multiplication of pathogens such as L. pneumophila and the protozoan parasite Leishmania (L.) amazonensis. Although further investigation are required to support the use of the method for generation of dendritic cells, preliminary experiments indicate that bone marrow-derived dendritic cells can also be generated from cryopreserved BM cells. Overall, the method described and validated herein represents a technical advance as it allows ready and easy generation of BMDM from a stock of frozen BM cells.

Hemozoin from Schistosoma japonicum does not affect murine myeloid dendritic cell function

Hemozoin (Hz) formation is a byproduct of hemoglobin digestion in some hematophagous organisms. Although Hz produced by Plasmodium falciparum (PfHz) has been shown to affect development and activities of human dendritic cells (DCs), the effects of Schistosoma Hz on DCs have not been elucidated. Our data presented in this report demonstrated that native Schistosoma japonica Hz (SjHz) did not affect the differentiation of murine bone marrow cells into immature DCs (imDCs). Maturation and stimulatory activities to T cells by imDCs induced by LPS were not altered in the presence of SjHz; whereas purified PfHz induced a slight increase in CD40 expression and enhanced IL-12p40 secretion. Lastly, SjHz treatment did not significantly affect the phagocytic activities of DCs. These data suggested that SjHz failed to exert any significant effects on the development and activities of murine myeloid DCs. The mechanisms of different effects on DCs by SjHz and PfHz remain to be elucidated.

Expression and function of the inducible costimulator ligand B7-H2 in human airway smooth muscle cells

BACKGROUND

B7-H2 is a ligand for the inducible costimulator (ICOS). The aim of this study was to examine the expression and function of B7-H2 in human airway smooth muscle (ASM) cells and compare them with those of CD40 or OX40 ligand (OX40L).

METHODS

Expression of B7-H2, CD40 and OX40L in ASM cells and their respective counterparts in T cells was analyzed by RT-PCR or flow cytometry. The modulating effect of polyinosinic-polycytidylic acid (poly I:C) on expression of B7-H2, CD40 and OX40L was also examined. The function of these three molecules was evaluated by virtue of adhesion of anti-CD3-activated T cells, IL-6 and IL-8 production and DNA synthesis.

RESULTS

ASM cells constitutively expressed B7-H2, CD40 and OX40L that mediated adhesion of activated T cells expressing ICOS, CD40L and OX40. ASM cells responded to poly I:C with upregulated expression of B7-H2, CD40 and OX40L and displayed enhanced adhesion of activated T cells. Functional analysis performed on untreated ASM cells showed that engagement of B7-H2 with ICOS-Ig clearly induced DNA synthesis, whereas that of CD40 or OX40L with trimeric CD40L or OX40-Ig greatly increased IL-6 and IL-8 production. These responses were enhanced in poly I:C-treated ASM cells.

CONCLUSIONS

The data demonstrate that ASM cells express functionally active B7-H2, CD40 and OX40L and suggest that B7-H2-dependent signaling may play an active role in a proliferative response rather than in cytokine and chemokine production. In addition, the modulation of B7-H2, CD40 and OX40L expression and function by poly I:C may have important implications for the function of virus-infected ASM cells.

SOCS2 influences LPS induced human monocyte-derived dendritic cell maturation

Dendritic cells (DCs) are highly specific antigen presenting cells, which link innate and adaptive immune responses and participate in protecting hosts from invading pathogens. DCs can be generated in vitro by culturing human monocytes with GM-CSF and IL-4 followed by LPS induced DC maturation. We set out to study the suppressor of cytokine signaling (SOCS) proteins during maturation and activation of human monocyte-derived DCs from peripheral blood in vitro. We found that the expression of SOCS2 mRNA and protein is dramatically up-regulated during DC maturation. Silencing of SOCS2 using siRNA, inhibited DC maturation as evidenced by a decreased expression of maturation markers such as CD83, co-stimulatory molecules CD40, CD86 and HLA-DR. Furthermore, silencing of SOCS2 decreased LPS induced activation of MAP kinases (SAKP/JNK, p38, ERK), IRF3, decreased the translocation of the NF-kappaB transcription factor and reduced downstream gene mRNA expression. These results suggest a role for SOCS2 in the MyD88-dependent and -independent TLR4 signaling pathways. In conclusion, our results demonstrate that SOCS2 is required for appropriate TLR4 signaling in maturating human DCs via both the MyD88-dependent and -independent signaling pathway.

The molecular mechanisms of immunomodulation and tolerance induction to factor VIII

Successful factor (F) VIII replacement therapy in hemophilia A patients is confounded by the generation of inhibitory anti-FVIII antibodies (Ab) in 25-30% of treated patients. These antibodies, termed 'inhibitors', significantly increase morbidity within the hemophilia population and lower the quality of life for these patients. For the past 30 years, immune tolerance induction (ITI) has been the standard therapy to elicit immunological tolerance to FVIII in the clinic. ITI works well in approximately 75% of patients, but it is expensive, can take years to show effect and is in many cases practically challenging. Therefore, new immunological tolerance induction strategies are now being designed and tested in hemophilia A animal models. This review attempts to provide a comprehensive description, at both the cellular and molecular levels, of these novel advances in tolerance induction and immunomodulation of FVIII. We begin by briefly reviewing why and how the immune system generates a protective response against exogenous FVIII. This leads to a discussion of the latest advances in FVIII tolerance/immunomodulation technology. These advances include interesting methodologies to induce B cell specific tolerance in FVIII primed humans and animals, as well as newer T cell-specific therapies that modify and/or block co-stimulation. We also discuss methods to manipulate FVIII loading of antigen-presenting cells.

Toll-like receptor 9-dependent activation of myeloid dendritic cells by Deoxynucleic acids from Candida albicans

The innate immune system of humans recognizes the human pathogenic fungus Candida albicans via sugar polymers present in the cell wall, such as mannan and beta-glucan. Here, we examined whether nucleic acids from C. albicans activate dendritic cells. C. albicans DNA induced interleukin-12p40 (IL-12p40) production and CD40 expression by murine bone marrow-derived myeloid dendritic cells (BM-DCs) in a dose-dependent manner. BM-DCs that lacked Toll-like receptor 4 (TLR4), TLR2, and dectin-1, which are pattern recognition receptors for fungal cell wall components, produced IL-12p40 at levels comparable to the levels produced by BM-DCs from wild-type mice, and DNA from a C. albicans pmr1Delta null mutant, which has a gross defect in mannosylation, retained the ability to activate BM-DCs. This stimulatory effect disappeared completely after DNase treatment. In contrast, RNase treatment increased production of the cytokine. A similar reduction in cytokine production was observed when BM-DCs from TLR9(-/-) and MyD88(-/-) mice were used. In a luciferase reporter assay, NF-kappaB activation was detected in TLR9-expressing HEK293T cells stimulated with C. albicans DNA. Confocal microscopic analysis showed similar localization of C. albicans DNA and CpG-oligodeoxynucleotide (CpG-ODN) in BM-DCs. Treatment of C. albicans DNA with methylase did not affect its ability to induce IL-12p40 synthesis, whereas the same treatment completely eliminated the ability of CpG-ODN to induce IL-12p40 synthesis. Finally, impaired clearance of this fungal pathogen was not found in the kidneys of TLR9(-/-) mice. These results suggested that C. albicans DNA activated BM-DCs through a TLR9-mediated signaling pathway using a mechanism independent of the unmethylated CpG motif.

Ganoderma lucidum induces the expression of CD40/CD86 on peripheral blood monocytes

BACKGROUND

The major immuno-modulating effects of Ganoderma lucidum include mitogenicity and activation of immune effector cells such as T cells, macrophages and natural killer cells resulting in the production of cytokines.

OBJECTIVE

The purpose of this study was to evaluate the expression of CD40 and CD80 by G. lucidum-treated human peripheral blood mononuclear cells.

METHODS

Monocytes were isolated and incubated at 37 C and 5% CO2 for 24 h and 48 h in the presence or absence of different concentrations of G. lucidum. Cells were then incubated with labelled monoclonal antibodies against CD14, CD40 and B7-1(CD80) molecules utilizing standard protocols, and analyzed by flow cytometry.

RESULTS

The results showed that incubation of monocytes with G. lucidum led to marked enhancement of CD40 and B7-1 expression in a dose- and time- dependent manner (p<0.001). G. lucidum was more effective in enhancing the expression of CD80 and CD40 molecules of cells obtained from females than male donors (p<0.001).

CONCLUSION

G. lucidum enhanced the expression of CD40 and CD80 molecules on peripheral blood monocytic cells derived from both sexes in a dose-dependent manner, with a preferential higher effect on cells obtained from female donors.

Expression of CD40 by the cells of benign and malignant breast tumors and antitumor action of autologous lymphocytes against chemoresistant and chemosensitive tumors

AIM

To study the expression of CD40 by cells of benign and malignant tumors of mammary gland, and to compare the efficacy of lymphocytes antitumor activity against drug resistant and sensitive breast tumors in relevance to CD40 expression.

METHODS

Breast tumor explants were cultured with autologous lymphocytes in double diffusion chambers. The results were evaluated by morphological criteria of explants growth. Expression level of molecules on tumor cells was analyzed using immunohistochemical method (paraffin embedded slides), and on lymphocytes - by the method of indirect immunofluorescence.

RESULTS

The highest level of CD40 expression was detected on cells of chemoresistant malignant breast tumors, and the lowest one - on cells of benign breast tumors. The decreased CD40 expression on lymphocytes from patients with drug resistant breast cancer was compared with that on lymphocytes of the patients with drug sensitive breast cancer. The study of antitumor activity of autologous lymphokine activated killer cells (LAK) has shown their pronounced antitumor activity against drug resistant malignant breast tumors.

CONCLUSION

Marked antitumor activity of LAK from the patients with drug resistant breast cancer is associated with high expression level of CD40 on tumor cells and with its decreased expression on lymphocytes.

Delivery of rapamycin by PLGA nanoparticles enhances its suppressive activity on dendritic cells

The purpose of this study was to evaluate the effect of rapamycin delivery by poly (D,L-lactic-co-glycolic acid) (PLGA) nanoparticles on the maturation of dendritic cells (DCs). DCs were generated from mouse bone marrow and exposed to particulate and soluble rapamycin without any additional treatment, or with pre- or posttreatment with lipopolysaccharide (LPS). Annexin V-FITC/PI staining was performed on DC cultures to assess the viability of DCs during study. Surface phenotype of DCs was characterized for the expression of maturation markers, that is, MHC class II, CD86, and CD40 by flow cytometry. Cell culture supernatants were analyzed for the production of TGF-beta, IL-12, and IL-10 cytokines using sandwich ELISA method. DCs from Balb/C mice were cocultured with T cells from C57BL/6 mice and allogenic mixed lymphocyte reaction was assessed by [3H]-Thymidine incorporation. Unlike free rapamycin that has shown little if any effect on the expression of maturation markers in immature DCs, PLGA encapsulated rapamycin decreased the expression of all maturation markers under the study, that is, MHC class II, CD86, and CD40, significantly. LPS pre- or posttreated DCs demonstrated decreased expression of MHC class II, CD86, and CD40 in the presence of soluble or encapsulated rapamycin. The cytokine secretion profiles revealed high levels of TGF-beta and very low levels of IL-10 and IL-12 production. Rapamycin in soluble or encapsulated form significantly inhibited mixed lymphocyte reaction in DCs. The inhibitory effect of rapamycin on the maturation of DCs with respect to DC phenotype, cytokine production, and functional effects on the proliferation of T cells was significantly increased by PLGA delivery.

The glycoprotein-hormones activin A and inhibin A interfere with dendritic cell maturation

BACKGROUND

Pregnancy represents an exclusive situation in which the immune and the endocrine system cooperate to prevent rejection of the embryo by the maternal immune system. While immature dendritic cells (iDC) in the early pregnancy decidua presumably contribute to the establishment of peripheral tolerance, glycoprotein-hormones of the transforming growth factor beta (TGF-beta) family including activin A (ActA) and inhibin A (InA) are candidates that could direct the differentiation of DCs into a tolerance-inducing phenotype.

METHODS

To test this hypothesis we generated iDCs from peripheral-blood-monocytes and exposed them to TGF-beta1, ActA, as well as InA and Dexamethasone (Dex) as controls.

RESULTS

Both glycoprotein-hormones prevented up-regulation of HLA-DR during cytokine-induced DC maturation similar to Dex but did not influence the expression of CD 40, CD 83 and CD 86. Visualization of the F-actin cytoskeleton confirmed that the DCs retained a partially immature phenotype under these conditions. The T-cell stimulatory capacity of DCs was reduced after ActA and InA exposure while the secretion of cytokines and chemokines was unaffected.

CONCLUSION

These findings suggest that ActA and InA interfere with selected aspects of DC maturation and may thereby help preventing activation of allogenic T-cells by the embryo. Thus, we have identified two novel members of the TGF-beta superfamily that could promote the generation of tolerance-inducing DCs.

The CD40/CD40 ligand system in the skin of patients with subacute cutaneous lupus erythematosus

OBJECTIVE

To investigate whether CD40 and CD40 ligand (CD40L) is expressed in the skin of patients with subacute cutaneous lupus erythematosus (SCLE).

METHODS

Six female patients with SCLE were studied. Skin biopsies were obtained from lesional and healthy sunprotected skin. Frozen sections were stained immunohistochemically using monoclonal antibodies to CD4, CD40, and CD40L. As controls we used 5 patients with discoid LE (DLE), 5 with dermatomyositis (DM), 3 with lichen planus (LP), and 2 with erythema multiforme (EM), as well as the normal-appearing skin of 5 healthy volunteers.

RESULTS

The CD40 was intensely expressed in all SCLE, DLE, and DM lesions, and only focally in healthy sunprotected skin specimens. The number of CD40+ cells in SCLE dermis was lower than in DLE, similar to that in DM, LP and EM, and higher than in SCLE sunprotected skin. CD40L+ cells infiltrated the SCLE, DLE, DM, LP, and EM lesional dermis, and were more numerous in SCLE lesional skin than in SCLE healthy sunprotected skin.

CONCLUSION

We showed that the CD40/CD40L system may represent an important pathway of induction of SCLE lesions. The expression of such costimulatory system in healthy sunprotected skin also may signify that its abnormal activation is constitutive in SCLE, as previously observed in systemic LE.

Leptin Induces CD40 Expression through the Activation of Akt in Murine Dendritic Cells

Increasing evidence suggests a regulatory role for leptin, an adipocyte-derived hormone, in immunity. Although recent studies indicated an essential role of leptin signaling in dendritic cell (DC) maturation, the molecular mechanisms by which leptin modulates DC functional maturation remained unclear. In this study, we showed that leptin induced CD40 expression in murine DC and significantly up-regulated their immunostimulatory function in driving T cell proliferation. Moreover, leptin markedly enhanced lipopolysaccharide-mediated DC activation. Using pharmacological inhibitors for Akt, STAT-1alpha, or NF-kappaB and the dominant negative forms of Akt and IkappaB kinase alpha/beta/gamma, as well as small interfering RNA for STAT-1alpha, we showed that Akt, STAT-1alpha, and NF-kappaB were important for the leptinor lipopolysaccharide-induced CD40 expression. Coimmunoprecipitation analysis revealed that leptin promoted immune complex formation between Akt and the IkappaB kinase subunits as well as STAT-1alpha. Blocking the activity of Akt demonstrated a crucial role for Akt in translocation of STAT-1alpha and NF-kappaB to the nucleus and activation of the CD40 promoter. Further analysis with chromatin immunoprecipitation assay confirmed that leptin recruited STAT-1alpha, NF-kappaBp65, and RNA polymerase II to the CD40 promoter and enhanced histone 4 acetylation in a time-dependent manner. Thus, our results have elucidated the molecular mechanisms underlying leptin-induced CD40 expression and DC maturation.

Complement C5a anaphylatoxin is an innate determinant of dendritic cell-induced Th1 immunity toMycobacterium bovisBCG infection in mice

During acquired immunity to Mycobacterium bovis bacillus Calmette-Guerin (BCG) infection in mice, dendritic cells (DCs) present mycobacterial antigens to naive T cells to prime an immune response. Complement C5a (anaphylatoxin) secreted by mycobacteria-infected macrophages regulates IL-12p70 production. As IL-12p70 regulates Th1 immunity against mycobacteria in mice, we examined the effects of C5a on IL-12p70 secretion by murine DCs and Th1 immunity. DCs cultured from C5-deficient (C5(-/-)) and -sufficient (C5(+/+)) mice were infected with BCG in the presence or absence of the C5a peptide. ELISA showed that C5(-/-) DCs secreted less IL-12p70 (600 pg/mL vs. 100 pg/mL) than C5(+/+) DCs, and they secreted more IL-10. Using immunophenotyping, reduced CD40 expression was found on C5(-/-) DCs after BCG infection. BCG-primed DCs were then cocultured with naive or BCG-immune T cells to differentiate them into IFN-gamma-secreting Th1 T cells. Coincident with increased IL-12p70 levels, BCG-primed C5(+/+) DCs cocultured with naive or immune C5(+/+) T cells showed a larger increase in CD4+ IFN-gamma/CD8+ IFN-gamma+ T cells compared with cocultured DCs and T cells from C5(-/-) mice. Thus, BCG-primed C5(+/+) DCs were better able to drive a Th1 response. Furthermore, BCG aerosol-infected C5(-/-) mice showed reduced CD4 and CD8 IFN-gamma-secreting T cells in the lungs, concurrent with an increased growth of BCG. Thus, C5a, an innate peptide, appears to play an important role in the generation of acquired immune responses in mice by regulating the Th1 response through modulation of IL-12p70 secretion from DCs.

Tumor cells prevent mouse dendritic cell maturation induced by TLR ligands

Tumor cells can evade the immune system through several mechanisms, one of which is to block DC maturation. It has been suggested that signaling via Toll-like receptors (TLR) may be involved in the induction of prophylactic anti-cancer immunity and in the treatment of established tumors. In the present study we found that high numbers of tumor cells interfere with BMDC activation induced by the TLR ligands LPS and poly IC. Tumor cells blocked TLR3- and TLR4-mediated induction of MHCII and the co-stimulatory molecules CD40 and CD86, as well as the cytokines IL-12, TNF-alpha and IL-6. Importantly, tumor cells induced inhibitory molecules (B7-DC, B7-H1 and CD80) on spleen DC in vivo and on BMDC, even in the presence of TLR ligands. Moreover, after a long exposure with tumor cells, purified BMDC were unable to respond to a second challenge with TLR ligands. The failure of tumor exposed-BMDC to express co-stimulatory molecules and cytokines in the presence of TLR ligands has implications for the future development of DC-based cancer immune therapies using TLR ligands as adjuvants for the activation of DC.

Regulation of Transcript Elongation through Cooperative and Ordered Recruitment of Cofactors

We studied the regulation of murine CD80, a gene whose basal transcriptional status was characterized by the presence of a stalled RNA polymerase II complex on the promoter-proximal region. Stimulus-induced activation of productive elongation involved a complex interplay of regulated events that included a synergy between ordered cofactor recruitment. This cascade of recruitments was initiated through the engagement of transcription factor NF-kappaB, leading to the temporal association of histone acetyltransferases and the consequent selective acetylation of a transcription start site downstream nucleosome. This in turn culminated into the nucleosomal association of Brd4-associated P-TEFb, a protein complex containing kinase specific for serine 2 of Rbp 1, the largest subunit of the carboxyl-terminal domain of RNA polymerase II. The consequent phosphorylation of serine 2 residues in CTD by CDK9 in the P-TEFb complex then facilitated escape of polymerase II into the productive elongation phase. Thus, the cooperative mechanisms that integrate between independent pathways characterize regulation of the elongation step of transcription, thereby providing another level at which specificity of gene regulation can be achieved.

Effects of synchronization on CD40 expression and antibody production in hybridoma cells stimulated with anti-mIgG

In previous experiments with the 55-6 hybridoma cell line, we showed that cell stimulation with anti-mouse surface immunoglobulin G antibody (anti-mIgG) increased both CD40 expression and specific monoclonal antibody (mAb) production rate. Cell preincubation with lipopolysaccharide (LPS) prior to anti-mIgG stimulation enhanced these results. Moreover, the expression of both CD40 and surface immunoglobulin G (sIgG) were higher for cells in the G1 phase of the cell cycle. Therefore, to determine the relationship between cell cycle position, CD40 expression, and mAb productivity, in this work cells were synchronized in the G1 phase by thymidine block. In addition, synchronized cells were subjected to different treatments with anti-mIgG. Although synchronized cells showed a slight increase in both CD40 expression and maximum specific growth rate (mu max) compared with unsynchronized cells, specific productivity did not show significant changes. However, the stimulation of synchronized cells with anti-mIgG increased over 65% the expression of CD40 and over 50% the specific productivity in comparison with that obtained on unsynchronized cells after anti-mIgG stimulation. These data improved additionally over 15 and 60%, respectively, by adding 2 mM thymidine to the culture medium. These results suggest that the effect of the positive association between G1 phase, CD40 expression, and specific productivity is subordinated to the effect of anti-mIgG stimulation, which is enhanced by increasing the percentage of cells on the G1 phase of the cell cycle. Contrary to expectations, LPS preincubation of synchronized cells prior to anti-mIgG stimulation did not increase the specific productivity in comparison with non-preincubated cells, and the expression of CD40 was minor compared to that on non-preincubated cells.

Phagocytosis ofFonsecaea pedrosoiconidia, but not sclerotic cells caused by Langerhans cells, inhibits CD40 and B7-2 expression

Fonsecaea pedrosoi is the major etiological agent of chromoblastomycosis, a chronic, suppurative, granulomatous mycosis usually confined to skin and subcutaneous tissues, presenting a worldwide distribution. The host defense mechanisms in chromoblastomycosis have not been extensively investigated. Langerhans cells (LC) are bone-marrow-derived, dendritic antigen-presenting cells of the epidermis, which constitutively express major histocompatibility complex (MHC) class II, and comprise 1-3% of total epidermal cells. LC are localized in suprabasal layers of the epidermis and in mucosa, where they play important roles in skin immune responses. The purpose of the present study was to evaluate the interaction of F. pedrosoi conidia or sclerotic cells with LC purified from BALB/c mice skin. We demonstrate here that LC phagocytose F. pedrosoi conidia but not sclerotic cells in the first 3 h of interaction, inhibiting hyphae formation during 12-hour coculture from both forms, internalized or not. Also, LC maturation, analyzed using CD40 and B7-2 expression, was inhibited by conidia, but not by sclerotic cells, indicating an important innate immunity function of LC against F. pedrosoi infection in these mice.

CD40-40L Signaling in Vascular Inflammation

Ligation of CD40 in circulating cells or in the vessel wall may promote mononuclear cell recruitment, participate in the weakening of the plaque, and contribute to thrombosis. This process appears to be redox-sensitive, but the precise signaling mechanism by which the interaction between CD40L and its receptor CD40 mediates inflammatory secretion is unclear. Our previous studies have shown that the CD40-CD40L interaction modulates release of reactive oxygen species (ROS) and the current findings demonstrate that in endothelial cells CD40L dose dependently induces intracellular CD40L and MCP1 release in a redox sensitive manner. Pharmacological inhibition of phosphatidylinositol 3-kinase and p38 MAPK as well as adenovirus-mediated inactivation of Akt and p38 MAPK inhibited CD40L effects on endothelial cells. Akt, in particular, appeared to mediate CD40L-induced CD40L synthesis and MCP1 release by endothelial cells in a redox sensitive manner via NFkappaB activation. In addition, using confocal microscopy, exogenous addition of recombinant CD40L or adenoviral mediated CD40L overexpression was found to stimulate nuclear translocation of NFkappaB, which was further augmented by Akt overexpression and inhibited by Akt inactivation. These data support a mechanism whereby redox-sensitive CD40-CD40L interactions induce activation of Akt and p38 MAPK, leading to stimulation of NFkappaB and enhanced synthesis of CD40L and MCP1. Increased CD40L and MCP1 may contribute to the adherence of CD40-positive cells, such as platelets and monocytes, to the vessel wall modulating atherothrombosis.

Bidirectional membrane molecule transfer between dendritic and T cells

The acquisition of dendritic cell (DC) molecules by T cells has been previously reported. However, it remains unclear whether the transfer is only mono- or bidirectional. In this study, we incubated CMFDA-labeled ovalbumin (OVA)-pulsed DC2.4 (DC2.4(OVA)) cells with Dil-labeled OT II CD4(+) T cells and analyzed the potential bidirectional molecule transfer. We also assessed the distribution of internalized membrane using two engineered DC2.4/Ia(b)GFP and MF4/TCRCFP DC lines. Our findings showed that membrane molecule transfer is bidirectional. CD4(+) T cells acquired Ia(b), CD11c, CD40, and CD80 from DC2.4(OVA) cells, and conversely DC2.4(OVA) cells took up CD4, CD25, CD69, and T cell receptor from T cells. The internalized molecules acquired by T cells and DCs mostly localized in endosomes and lysosomes, respectively. Taken together, this study demonstrated a novel phenomenon of bidirectional membrane molecule transfer between DCs and T cells.

Distinct pathways for signaling maturation in macrophages and dendritic cells after infection with paramyxovirus simian virus 5

Professional antigen-presenting cells are critical components of both the innate and adaptive immune responses. Although dendritic cells (DCs) are generally thought to be the primary activators of naive T cells, macrophages have also been shown to fulfill this role. As with DCs, the capacity to induce optimal activation of T cells requires that macrophages undergo a process that results in the increased expression of costimulatory molecules, such as CD40, CD80, and CD86, and the production of cytokines. In this study we analyzed the effect of infection of macrophages generated from BALB/c mice with the paramyxovirus simian virus 5 (SV5). Here we have shown that bone marrow-derived macrophages (BMMs) are not productively infected at any multiplicity of infection tested. Analysis of activation markers revealed that SV5-infected BMMs robustly upregulated CD40 and modestly upregulated CD86, but did not upregulate the expression of CD80. Further, SV5-infected BMMs secreted low levels of interferon-beta and interleukin (IL)-12p40, but high levels of tumor necrosis factor-alpha and IL-6. Intriguingly, upregulation of these molecules on BMMs, unlike our previous results using bone marrow-derived dendritic cells, was not dependent on live virus. These findings provide evidence that different professional antigen-presenting cells can detect and respond to virus via distinct mechanisms.

Altered CD40 and E-cadherin expression--putative role in oral lichen planus

BACKGROUND

Oral lichen planus (OLP) is characterized among other features by apoptosis of basal keratinocytes. To identify potential regulatory mechanisms associated with basal cell apoptosis in OLP, we investigated the expression of CD40, CD40 ligand (CD40L), CD44 and epithelial (E)-cadherin.

METHODS

Biopsies from 22 patients with OLP were investigated by immunohistochemistry for detection of CD40, CD40L, E-cadherin, CD44, Laminin-5 and Collagen IV, double-labelling for CD40 and CD3, and in situ mRNA hybridization for CD40 and CD40L.

RESULTS

In actively diseased areas of OLP lesions, basal keratinocytes did not express CD40 and were focally E-cadherin-negative, in contrast to non-diseased areas and normal oral mucosa. Demonstration of intraepithelial T cells expressing CD40 and CD40L, indicates a potential role in inflammatory cell responses involved in the disease process of OLP.

CONCLUSION

T cells may orchestrate inflammatory cell responses in OLP via CD40-CD40L interactions. As basal keratinocytes downregulate CD40, they may escape CD40-CD40L-induced apoptosis in OLP. On the other hand, loss of E-cadherin expression may contribute to epithelial basal cell destruction and T-cell migration into the epithelial compartment in OLP.

Platelet expression of CD40/CD40 ligand and its relation to inflammatory markers and adhesion molecules in patients with atrial fibrillation

Recent studies suggest the importance of prothrombotic and proinflammatory cascades in vascular thrombus formation. However, the impact of platelet CD40 and CD40 ligand (CD40L) expression and its relation to inflammatory markers in atrial clot formation have not yet been determined. Therefore, we studied a total of 40 patients. A total of 20 patients with persistent atrial fibrillation (AF) and 20 matched patients with sinus rhythm (SR) were included to quantify platelet surface expression of CD40/CD40L, serum levels of intercellular adhesion molecule-1 (ICAM), vascular adhesion molecule-1 (VCAM), high-sensitivity C-reactive protein (hsCRP), and monocyte chemoattractant protein-1 (MCP-1). Using fluorescence-activated cell sorting analysis, baseline CD40 expression (antibody binding capacity [ABC]) was increased during AF (AF: 7776 +/- 8.46 ABC vs. SR: 7753 +/- 7.32 ABC; P < 0.05), whereas CD40L expression was not different. In contrast to the effect of adenosine diphosphate, ex vivo stimulation with thrombin receptor activating peptide (TRAP) increased CD40 and CD40L expression in both groups. MCP-1, hsCRP, ICAM, and VCAM levels were significantly increased during AF, reaching highest levels in patients with atrial thrombi. Importantly, VCAM and MCP-1 were independent predictors for atrial thrombi (P < 0.05) using multivariate analysis. In contrast to declining levels of hsCRP, levels of ICAM, VCAM, MCP-1, and platelet CD40 expression remained elevated 5 weeks after successful electrical direct current cardioversion (CV). In conclusion, prothrombogenic markers are substantially elevated in patients with AF, reaching highest levels in patients with AF and atrial thrombi. Interestingly, amounts of adhesion molecules and platelet CD40 levels remain elevated even 5 weeks after successful CV, which may imply a persistently increased risk for atrial thrombus formation. In addition to hsCRP, MCP-1 and VCAM may serve as new biomarkers, which may help to identify patients with an increased risk for thromboembolic events.

Pharmaceutical analysis of synthetic lipid A-based vaccine adjuvants in poly (D,L-lactic-co-glycolic acid) nanoparticle formulations

The present study had two main objectives. First, was to compare the immune stimulatory effect of two synthetic lipid A analogues (7-acyl lipid A and pentaerythritol-based lipid A (PET lipid A)) on maturation/stimulation of bone marrow derived dendritic cells (DCs). Our second objective was to develop a liquid chromatography/mass spectrometry (LC-MS) method for the quantitative analysis of lipid A-based vaccine adjuvants. Treatment of immature DCs with 7-acyl lipid A and PET lipid A up regulated the surface expression of CD86 and CD40 molecules, and also induced similar profile of pro-inflammatory cytokine secretion. LC-MS analyses were performed using a Waters Micromass ZQ 4000 spectrometer, coupled to a Waters 2795 separations module with an autosampler. Calibration curves with R(2)>0.999 were constructed over the concentration range of 1.25-20 microg/ml for the solution of 7-acyl lipid A and PET lipid A. The method was tested in a 3 day validation protocol. The accuracy of the assay at different concentrations tested ranged from 89 to 108% and from 92 to 107% for 7-acyl lipid A and PET lipid A, respectively. The limit of quantification for both 7-acyl lipid A and PET lipid A was 1.25 microg/ml (signal/noise (S/N)) ratio >15:1. The sensitivity of the method (the limit of detection) was 0.35 and 0.15 ng for 7-acyl lipid A and PET lipid A, respectively (S/N ratio between 4:1 or 3:1). As a preliminary application, this method has been successfully applied to the determination of 7-acyl lipid A and PET lipid A content in poly (D,L-lactic-co-glycolic acid) nanoparticles (PLGA-NP).

Relationship between upregulation of CD40 system and restenosis in patients after percutaneous coronary intervention

AIM

To investigate whether the increasing CD40-CD40 ligand system is related to restenosis in patients after percutaneous coronary intervention (PCI).

METHODS

Twenty normal controls and 120 patients with PCI were investigated. The expression of CD40 and the CD40 ligand (CD40L) on platelets was analyzed by indirectimmunofluorescence flow cytometry. The serum level of soluble CD40L (sCD40L) and C-reactive protein (CRP) was determined by commercially available enzyme linked immunosorbent assay. Restenosis was observed in 120 patients within a 6 month follow-up period after PCI surgery.

RESULTS

Restenosis occurred in 29 patients (24.2%). Patients who developed restenosis showed higher levels of CD40-CD40L system compared with non-restenotic patients before PCI. All restenotic patients showed a significant increase in CD40 [66.9 +/-4.8, mean fluorescence intensity (MFI)] and CD40L (14.9 +/-1.8, MFI) co-expression on platelets as well as sCD40L (13.7 +/-1.7 ng/mL) compared with non-restenotic patients and controls during the 6 month follow-up period (P<0.01). Elevated sCD40L and CD40L were significantly correlated with the serum level of CRP after percutaneous transluminal coronary angioplasty and with lumen loss during the 6 month followup period.

CONCLUSION

The level of CD40L was associated with late restenosis after PCI indicating that restenosis is an inflammatory disorder.

Expression of CD40 and growth-inhibitory activity of CD40 ligand in ovarian cancer cell lines

OBJECTIVE

Soluble recombinant human CD40 ligand trimer (rhuCD40Lt) has shown antitumor activity in preclinical and clinical studies. We evaluated the effect of rhuCD40Lt on epithelial ovarian carcinoma (EOC) cell lines.

METHODS

Expression of the receptor, CD40, was determined by reverse transcriptase-polymerase chain reaction and flow cytometry, and antiproliferative effects of rhuCD40Lt, either alone or in combination with recombinant interferon-gamma (rIFN-gamma), were examined in 8 EOC lines.

RESULTS

Expression of CD40 was elevated in 5 out of 8 EOC cell lines examined by flow cytometry, and the presence of CD40 transcripts was detected by RT-PCR in all 8 cell lines. CD40 expression was increased by rIFN-gamma, but treatment with rhuCD40Lt decreased CD40 expression in 4 of the 5 lines that had shown elevated CD40 expression. rhuCD40Lt had a growth-inhibitory effect on 2774 cells, which also exhibited the highest level of CD40 expression. Growth-inhibitory effect of rhuCD40Lt was additive with rIFN-gamma on 2774, NMP-1, a cisplatin-resistant subline of OVCAR3, and HEY cell lines. The number of apoptotic tumor cells was increased following treatment with rhuCD40Lt.

CONCLUSIONS

CD40 is expressed on EOC cell lines, and expression was found at the transcript level in all of the EOC lines examined. rIFN-gamma enhances CD40 expression, though a decrease in CD40 expression was observed following treatment with rhuCD40Lt. Growth-inhibitory activity of rhuCD40Lt on EOC lines that express CD40 could be enhanced when rhuCD40Lt treatment was combined with rIFN-gamma. These results suggest that future studies of the combination of rhuCD40Lt and rIFN-gamma might warrant consideration.