Surface Of Monocyte-derived Dendritic Cells Research Articles

Secretomes derived from osteogenically differentiated jaw periosteal cells inhibit phenotypic and functional maturation of CD14+ monocyte-derived dendritic cells.

The jaw periosteal tissue is generally recognized as a suitable source for the isolation of mesenchymal stem cells (MSCs). In previous studies we showed evidence that two- and three-dimensionally cultured jaw periosteum-derived MSCs (JPCs) are able to induce a more immature phenotype of dendritic cells (DCs). To further expand our knowledge of JPCs' immunoregulative function, we investigated the effects of JPC secretomes derived from undifferentiated (CO) or osteogenically differentiated cells (treated with or without dexamethasone: OB+/-D) on CD14+ monocyte-derived DCs (MoDCs). We detected a remarkably reduced formation of MoDC homotypic clusters under the influence of secretomes from osteogenically induced JPCs. Further, significantly decreased numbers of CD83+ cells, up-regulated CD209 and down-regulated CD80, CD86 and CD197 expression levels were detected on the surface of MoDCs. Whereas secretomes from JPCs osteogenically stimulated with dexamethasone significantly enhanced FITC-dextran uptake capacity of MoDCs, the increase by secretomes of JPCs treated without dexamethasone did not reach significance. The analysis of mixed lymphocyte reactions revealed that OB+/-D secretomes were able to significantly reduce the numbers of proliferating CD14- peripheral blood mononuclear cells (PBMCs) and of proliferating CD4+ T cells. The OB-D secretome significantly promoted the expansion of regulatory CD25+ T cells. Regarding gene expression of MoDCs, remarkably up-regulated mRNA expression of CD209, HLA-DRA, CSF3, IL10 and IL8 was detected when DCs were cultured in the presence of OB+/-D secretomes. At the same time, secretomes seemed to have an impact in the down-regulation of IFNγ and IL12B gene expression. At protein level, OB+/-D secretomes significantly up-regulated IL-10 and IDO (indoleamine-pyrrole 2,3-dioxygenase) levels whereas IL-12/IL-23p40 levels were down-regulated in supernatants of MoDCs when cultured under the presence of OB+/-D secretomes. Taken together, while secretomes from untreated JPCs had only little effects on the process of maturation of MoDCs, secretomes derived from osteogenically induced JPCs were able to inhibit the phenotypic and functional maturation of MoDCs.

Further Increase in the Expression of Activation Markers on Monocyte-Derived Dendritic Cells in Coronary Artery Disease Patients with Ectasia Compared to Patients with Coronary Artery Disease Alone

Background. Coronary artery ectasia (CAE) is defined as localized or diffuse dilation of the coronary arteries. There are scarce data about the role of dendritic cells in CAE development. In this study we investigated the activation markers on the surface of monocyte-derived dendritic cells (mDCs) in coronary artery disease (CAD) patients with or without CAE. Method. The study consisted of 6 patients who had obstructive CAD with CAE, 6 CAD patients without CAE and 6 subjects with angiographically normal coronary arteries. mDCs were cultivated from peripheral blood monocytes. Surface activation markers were detected by flow cytometry. Results. CAD patients with CAE were detected to have significantly higher mean fluorescence intensities of CD11b, CD11c, CD54 , CD83, CD86 and MHC Class II molecules on mDCs in comparison to CAD patients without CAE and normal controls (P < .001 for all). A significant positive correlation was found between the number of vessels with CAE and the levels of CD11c, CD86, and MHC Class II molecules. Conclusion. mDCs display an increased cell surface concentration of activation molecules in CAD patients with CAE compared to patients with CAD alone. DC activation may play an important role for CAE development in patients with CAD.

Plasmodium vivax recombinant vaccine candidate AMA-1 plays an important role in adaptive immune response eliciting differentiation of dendritic cells

The Apical Membrane Antigen-1 (AMA-1) is a well-characterized and functionally important merozoite protein and is currently considered a major candidate antigen for a malaria vaccine. Previously, we showed that AMA-1 has an influence on cellular immune responses of malaria-naïve subjects, resulting in an alternative activation of monocyte-derived dendritic cells and induction of a pro-inflammatory response by stimulated PBMCs. Although there is evidence, from human and animal malaria model systems that cell-mediated immunity may contribute to both protection and pathogenesis, the knowledge on cellular immune responses in vivax malaria and the factors that may regulate this immunity are poorly understood. In the current work, we describe the maturation of monocyte-derived dendritic cells of P. vivax naturally infected individuals and the effect of P. vivax vaccine candidate Pv-AMA-1 on the immune responses of the same donors. We show that malaria-infected subjects present modulation of DC maturation, demonstrated by a significant decrease in expression of antigen-presenting molecules (CD1a, HLA-ABC and HLA-DR), accessory molecules (CD40, CD80 and CD86) and FcγRI (CD64) receptor ( P ≤ 0.05). Furthermore, Pv-AMA-1 elicits an upregulation of CD1a and HLA-DR molecules on the surface of monocyte-derived dendritic cells ( P = 0.0356 and P = 0.0196, respectively), and it is presented by AMA-1-stimulated DCs. A significant pro-inflammatory response elicited by Pv-AMA-1-pulsed PBMCs is also demonstrated, as determined by significant production of TNF-α, IL-12p40 and IFN-γ ( P ≤ 0.05). Our results suggest that Pv-AMA-1 may partially revert DC down-modulation observed in infected subjects, and exert an important role in the initiation of pro-inflammatory immunity that might contribute substantially to protection.

Adipose tissue-derived mesenchymal stem cells are more potent suppressors of dendritic cells differentiation compared to bone marrow-derived mesenchymal stem cells

Both mesenchymal stem cells (MSCs) and dendritic cells (DCs) are engaged in the regulation of the immune response parallel to their numerous functions. The main objective of this study was to compare the effects of mesenchymal stem cells isolated from human adipose tissue or human bone marrow on the expression of specific cell surface markers as well as the secretion of some cytokines by monocyte-derived dendritic cells. The set of methods used includes cell cultures, magnetic beads isolation of cells, flow cytometry, ELISA and proteome profiler kit assays. The results obtained show that MSCs isolated from human adipose tissue are more potent immunomodulators of differentiation of human DCs in comparison to the bone marrow-derived MSCs. In both cases the percentages of CD14+ cells were increased in co-cultures of MSCs and DCs and at the same time down-regulated the expression of CD80, CD86 and CD83 as in all experiments the effect of adipose tissue MSCs was stronger. Similarly, the secretion of IL-10 by dendritic cells was up-regulated in co-cultures of MSCs and dendritic cells and the effect was stronger when adipose tissue-derived MSCs were used. Taken together all results presented reveal the higher potential of the adipose tissue-derived MSCs to inhibit the differentiation and expression of functionally important co-stimulatory molecules on the surface of monocyte-derived dendritic cells than the bone marrow-derived MSCs.

Is mannan-binding lectin (MBL) detectable on monocytes and monocyte-derived immature dendritic cells?

MBL (mannan-binding lectin; also called mannose-binding lectin) is a circulating C-type lectin with a collagen-like region synthesized mainly by the liver. MBL may influence susceptibility to infection in recipients of stem cell transplants, and it has even been suggested that the MBL status of a donor can influence the recipient's susceptibility to post-transplant infections. We have previously reported that MBL can be detected on human monocytes and monocyte-derived dendritic cells, based on detection using biotinylated anti-MBL, suggesting that those cells could synthesize MBL. If true, permanent MBL replacement therapy could be achieved by stem cell infusions. However, two other groups independently failed to find mbl-2-derived mRNA in monocytes. Therefore, to confirm or refute our previous observations, we used an alternative experimental strategy. Instead of using biotinylated antibody and labelled streptavidin, detection of surface MBL was attempted using MBL-specific primary antibodies (131-1, 131-10 and 131-11) followed by fluorescein-labelled anti-IgG, and controlled by the use of non-specific IgG as primary antibody. Monocytes were counterstained with anti-CD14-PE before FACS analysis. Adherent monocytes were also cultured for 48 h in serum-free medium or converted into immature dendritic cells by culture with IL-4 (interleukin-4) and GM-CSF (granulocyte/monocyte colony-stimulating factor). During FACS analysis, the dendritic cells were gated after counter-staining with anti-CD1a-PE. MBL was readily detected on the surface of fresh monocytes using all three specific anti-MBL monoclonal antibodies, but specific anti-MBL binding was greatly diminished after monocytes had been cultured for 2 days in serum-free medium. Moreover, we could not detect any MBL present on the surface of monocyte-derived dendritic cells. We therefore conclude that MBL is indeed present on the surface of fresh human monocytes. However, in view of the mRNA findings of others and our own previous observation that no secretion of MBL took place in culture, we presume that the surface-bound MBL is derived from autologous plasma and not synthesized by the cells. This conclusion is consistent with our in vivo findings in stem cell transplant patients which provided evidence against significant extra-hepatic production of serum MBL. It provides no ready explanation for the remarkable observation of Mullighan, Heatley, Doherty, Szabo, Grigg, Hughes, Schwarer, Szer, Tait, Bik To and Bardy [(2002) Blood 99, 3524-3529] that the presence of variant alleles of mbl-2 in stem cell donors can influence susceptibility to serious infections in their recipients.

Prostaglandin E2 is a key factor for CCR7 surface expression and migration of monocyte-derived dendritic cells

Dendritic cells (DCs) are potent antigen-presenting cells that are able to initiate and modulate immune responses and are hence exploited as cellular vaccines for immunotherapy. Their capacity to migrate from peripheral tissues to the T-cell areas of draining lymph nodes is crucial for the priming of T lymphocytes. In this study, we investigated how the maturation of human monocyte-derived DCs (MoDCs) by several different stimuli under serum-free conditions affected their T-cell stimulatory function, cytokine secretion, and migratory behavior. Surprisingly, we found that for all maturation stimuli tested, the addition of prostaglandin E2 (PGE2) was required for effective migration of MoDCs toward the lymph node-derived chemokines CCL19 (EBI1 ligand chemokine/macrophage inflammatory protein--3beta) and CCL21 (secondary lymphoid tissue chemokine [SLC]/6Ckine). Costimulation with PGE2 enhanced the expression of the CCL19/CCL21 receptor CCR7 on the cell surface of MoDCs when they were matured with soluble CD40 ligand or proinflammatory cytokines, but did not affect CCR7 expression of polyI:C-stimulated MoDCs. The effects of PGE2 on MoDCs were mediated through increased cyclic adenosine monophosphate by 2 of the known PGE2 receptors, EP2 and EP4, which are expressed and down-regulated after PGE2 binding in these cells. In conclusion, our results suggest that signals provided by the proinflammatory mediator PGE2 are crucial for MoDCs to acquire potent T-helper cell stimulatory capacity and substantial chemotactic responsiveness to lymph node-derived chemokines. This is a new and important parameter for the preparation of MoDCs as cellular vaccines in tumor immunotherapy. (Blood. 2002;100:1354-1361)

Synthesis and release of B-lymphocyte stimulator from myeloid cells

AbstractB-lymphocyte stimulator (BLyS) is a recently identified novel member of the tumor necrosis factor ligand superfamily shown to exist in a membrane-bound and soluble form. BLyS was found to be specifically expressed on cells of myeloid lineage and to selectively stimulate B-lymphocyte proliferation and immunoglobulin production. The expression of a cytokine involved in potentiation of humoral immune responses, such as BLyS, is expected to be strictly controlled. The goal of the present study was to examine regulation of BLyS levels in monocytic cells in response to cytokines and during their differentiation to macrophages and dendritic cells. The presence of BLyS on the cell surface and in the culture medium of both normal blood monocytes and on tumor cells of myelomonocytic origin was demonstrated. BLyS gene expression and levels of membrane-associated and soluble BLyS were found to be regulated by cytokines, in particular interferon (IFN)-γ and to a lesser extent interleukin-10 (IL-10). The expression of BLyS on monocyte membranes was retained following differentiation into macrophages, but detection on the surface of monocyte-derived dendritic cells required stimulation with IFN-γ. Both IFN-γ and IL-10 enhanced the release of soluble BLyS that was active in B-cell proliferation assays. Cells transfected with BLyS complementary DNA mutated in a predicted cleavage site failed to release BLyS into the culture medium, thereby suggesting that soluble BLyS was derived from the membrane form. These results provide further support for an important role for BLyS expressed in myeloid cells in B-cell expansion and antibody responses.