http://repub.eur.nl/res/aut/4578/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/39717/ 2013-03-01T00:00:00Z Relapse of tuberculosis (TB) is defined as re-emergence of clinical symptoms after stopping anti-TB treatment, while this treatment appeared effective initially. Relapse of TB can occur in patients that are therapy-compliant, but the risk of relapse is dramatically increased when patients are non-compliant. Additionally, the probability of antibiotic resistance is higher in those patients who have a relapse of TB and thus longer treatment is recommended. Further insight in the pathogenesis of relapsing TB could provide a basis for future treatment improvement. In the present study, using a murine TB model, we assessed the differences between primary TB and relapse of TB in terms of mycobacterial load in infected organs, (immuno-) histopathology, and plasma cytokine concentrations. Compared to primary TB, in relapse of TB we observed a lower mycobacterial load in lung, spleen and liver at the phase of established infection. Also the levels of TNF-α, IFN-γ, IL-6, MIG/CXCL9, IP-10/CXCL10 and IL-17 were significantly lower. It was observed that in relapse of TB memory Th-1 cells were locally and systemically expanded and congregated in the lung, permitting an efficient control of Mtb growth. Treatment response in relapse of TB is as good as the treatment response in primary TB; thereby no supportive evidence could be given for the recommended longer treatment duration in case of relapse of TB. http://repub.eur.nl/res/pub/33667/ 2011-06-30T00:00:00Z The objective of this study was to determine the effect of systemic delivery of prednisolone phosphate (PLP) encapsulated within long circulating 'stealth' liposomes on bone erosion and osteoclast activity during experimental antigen-induced arthritis (AIA). Liposomal PLP strongly suppressed knee joint swelling, synovial infiltrate and bone erosion in antigen-induced arthritis. The number of active osteoclasts was not only suppressed in bone lesions near inflamed synovium, but also within the trabecular bone of the tibia, suggesting a systemic suppression of osteoclast activation. Furthermore, liposomal PLP directly blocked osteoclast differentiation and bone resorption in vitro while it also suppressed expression of osteoclast differentiation factors M-CSF and RANKL in the synovium. Targeting studies showed that liposomes are most efficiently phagocytosed by macrophages and early precursors of osteoclasts in the bone marrow rather than by mature osteoclasts, indicating a possible inhibition of osteoclast differentiation from an early stage. Conclusion: Liposomal glucocorticoid delivery rather than free PLP offers a more efficacious way to inhibit both inflammation and bone erosion in rheumatoid arthritis. http://repub.eur.nl/res/pub/25772/ 2011-05-01T00:00:00Z Objective: Rheumatoid arthritis, which is associated with elevated levels of S100A8 and S100A9, is characterized by severe bone erosions caused by enhanced osteoclast formation and activity. The aim of the present study was to investigate the role of S100A8 and S100A9 in osteoclastic bone destruction in murine antigen-induced arthritis (AIA). Methods: Bone destruction was analyzed in the arthritic knee joints of S100A9-deficient mice in which S100A8 protein expression was also lacking, and in wild-type (WT) controls. Osteoclast precursors from S100A9-deficient and WT mice were differentiated into osteoclasts in vitro. Additionally, precursors were stimulated with S100A8, S100A9, or S100A8/A9 during osteoclastogenesis. Receptor involvement was investigated using an anti-receptor for advanced glycation end products (anti-RAGE)-blocking antibody, soluble RAGE, or Toll-like receptor 4 (TLR-4)-deficient osteoclast precursors. The formation of osteoclasts and actin rings, the regulation of osteoclast markers, and bone resorption were analyzed. Results: Bone erosions and cathepsin K staining were significantly suppressed in S100A9-deficient mice after AIA induction. However, osteoclast precursors from S100A9-deficient mice developed normally into functional osteoclasts, which excludes a role for intrinsic S100A8/A9. In contrast to the results observed with S100A9 and S100A8/A9, the addition of S100A8 during osteoclastogenesis resulted in stimulation of osteoclast formation in conjunction with enhanced actin ring formation and increased bone resorption. Analysis of the putative receptor for S100A8 in osteoclastogenesis revealed that osteoclast differentiation and function could not be inhibited by blocking RAGE, whereas the increase in osteoclast numbers and enhanced bone resorption were completely abrogated using TLR-4-deficient osteoclast precursors. Conclusion: These results demonstrate that S100A8 stimulated osteoclast formation and activity and suggest that both S100A8 and TLR-4 are important factors in mediating osteoclastic bone destruction in experimental arthritis. http://repub.eur.nl/res/pub/27401/ 2010-10-21T00:00:00Z Monocytes and cells of the dendritic cell lineage circulate in blood and eventually migrate into tissue where they further mature and serve various functions, most notably in immune defense. Over recent years these cells have been characterized in detail with the use of cell surface markers and flow cytometry, and subpopulations have been described. The present document proposes a nomenclature for these cells and defines 3 types of monocytes (classical, intermediate, and nonclassical monocytes) and 3 types of dendritic cells (plasmacytoid and 2 types of myeloid dendritic cells) in human and in mouse blood. This classification has been approved by the Nomenclature Committee of the International Union of Immunological Societies, and we are convinced that it will facilitate communication among experts and in the wider scientific community. http://repub.eur.nl/res/pub/27614/ 2010-08-15T00:00:00Z Monocytes perform diverse roles during infection with the facultative intracellular bacterium Listeria monocytogenes. They are essential as bactericidal cells in host defense but can also become Trojan horses transporting bacteria into the brain. To explain these contrasting roles, we characterized bone marrow (BM) monocytes in steady state and generated during lethal and sublethal L. monocytogenes infection. Ly-6ChighCD11b+BM monocytes expressed high amounts of M-CSFR/CD115 in steady state and 72 h following sublethal infection. However, infection with increasing numbers of bacteria resulted in progressive loss of CD115 and strongly decreased CD115-encoding c-fms mRNA expression. Conversely, analysis of regulatory molecules showed de novo expression of the nonsignaling IL-1RII, CD121b, under the same conditions. Ly-6ChighCD11b+monocytes in circulation also acquired a CD115neg/lowCD121bhighphenotype during lethal infection. These BM monocytes showed upregulation of suppressor of cytokine signaling 1 and 3 and IL-1R-associated kinase-M to a greater extent and/or earlier compared with cells from sublethal infection and showed decreased LPS-induced IL-6 production despite similar levels of surface TLR4 expression. BM monocytes from uninfected or sublethally infected mice bound and internalized very few L. monocytogenes in vitro. However, both functions were significantly increased in monocytes developing during lethal infection. Nonetheless, these cells did not produce reactive oxygen intermediates, suggesting an inability to kill L. monocytogenes. Together, these data show that systemic infections with lethal and sublethal amounts of bacteria differentially shape developing BM monocytes. This results in distinct phenotypic and functional properties consistent with being Trojan horses rather than bactericidal effector cells. http://repub.eur.nl/res/pub/20040/ 2010-08-01T00:00:00Z Listeria monocytogenes (Lm) is a bacterial pathogen that infects the brain via parasitized monocytes. CCR2 is important for monocyte migration into the brain after it is infected, but the degree of CCR2 involvement in monocyte migration to the CNS during systemic infection is less clear. Our recent data demonstrate that systemic infection with non-neuroinvasive ΔactA Lm mutants triggers IFN-γ-dependent brain influxes of Ly-6Chigh monocytes. Studies presented here tested the extent to which CCR2 and IFN-γ are essential for monocyte migration to the brain during systemic infection with virulent Lm. For this, we assessed expression of monocyte-attracting chemokines in brains of normal and IFN-γ mice during infection and tested the degree to which brain influxes of Ly-6Chigh monocytes were inhibited in chemokine- and chemokine receptor-deficient mice. In normal mice, systemic infection induced up-regulation of CCR2-binding (CCL2, CCL7, CCL8, CCL12) and CXCR3-binding chemokines (CXCL9, CXCL10). IFN-γ mice had negligible mRNA and protein expression of CXCR3-binding chemokines, whereas expression of CCR2-binding chemokines was reduced, but remained significant. In addition, infection-triggered monocyte influxes were significantly reduced in IFN-γ mice. Remarkably, brain monocyte influxes were normal during infection of CXCR3-, CCL2-, CCR1-, CCR5-, and CX3CR1-deficient mice. Influxes were transiently reduced in CCR2-/- mice, corresponding with retention of monocytes in the bone marrow but this was eventually overcome during infection. These data show that IFN-γ is critical for triggering brain influxes of Ly-6Chigh monocytes during systemic infection with virulent Lm. This initial burst of monocyte migration is largely independent of individual chemokine receptors. http://repub.eur.nl/res/pub/20514/ 2010-08-01T00:00:00Z Listeria monocytogenes (Lm) is a bacterial pathogen that infects the brain via parasitized monocytes. CCR2 is important for monocyte migration into the brain after it is infected, but the degree of CCR2 involvement in monocyte migration to the CNS during systemic infection is less clear. Our recent data demonstrate that systemic infection with non-neuroinvasive ΔactA Lm mutants triggers IFN-γ-dependent brain influxes of Ly-6Chigh monocytes. Studies presented here tested the extent to which CCR2 and IFN-γ are essential for monocyte migration to the brain during systemic infection with virulent Lm. For this, we assessed expression of monocyte-attracting chemokines in brains of normal and IFN-γ mice during infection and tested the degree to which brain influxes of Ly-6Chigh monocytes were inhibited in chemokine- and chemokine receptor-deficient mice. In normal mice, systemic infection induced up-regulation of CCR2-binding (CCL2, CCL7, CCL8, CCL12) and CXCR3-binding chemokines (CXCL9, CXCL10). IFN-γ mice had negligible mRNA and protein expression of CXCR3-binding chemokines, whereas expression of CCR2-binding chemokines was reduced, but remained significant. In addition, infection-triggered monocyte influxes were significantly reduced in IFN-γ mice. Remarkably, brain monocyte influxes were normal during infection of CXCR3-, CCL2-, CCR1-, CCR5-, and CX3CR1-deficient mice. Influxes were transiently reduced in CCR2-/- mice, corresponding with retention of monocytes in the bone marrow but this was eventually overcome during infection. These data show that IFN-γ is critical for triggering brain influxes of Ly-6Chigh monocytes during systemic infection with virulent Lm. This initial burst of monocyte migration is largely independent of individual chemokine receptors. http://repub.eur.nl/res/pub/27346/ 2010-04-01T00:00:00Z Background. Synthetic human chorionic gonadotropin (hCG)-related oligopeptides are potent inhibitors of pathogenic inflammatory responses induced by in vivo lipopolysaccharide exposure or hemorrhagic shock-induced injury. In this study, we tested whether hCG-related oligopeptide treatment similarly altered inflammatory responses and innate host defenses in mice during experimental Listeria monocytogenes infection. Methods. Mice were infected with L. monocytogenes and treated with hCG-related oligopeptides (LQGV, VLPALP, or AQGV) or phosphate-buffered saline. Subsequently, mice were analyzed for bacterial loads, cytokine and chemokine responses, and inflammatory cell infiltrates in target organs. Results. Oligopeptide administration increased bacterial numbers in the spleen and liver at 6 h after infection. Simultaneously, CXCL1/KC and CCL2/MCP-1 plasma levels as well as neutrophil numbers in the spleen, blood, and peritoneal cavity decreased. In contrast, at 18 h after infection, systemic tumor necrosis factor a, interleukin 12 p70, interleukin 6, and interferon y levels increased statistically significantly in oligopeptide-treated mice compared with controls, which correlated with increased bacterial numbers. Conclusion. These data show that treatment with hCG-related oligopeptides (LQGV, VLPALP, and AQGV) inhibits early innate immune activation by reducing initial chemokine secretion following infection. This leads to bacterial overgrowth with subsequent enhanced systemic inflammation. Our data underscore the importance of early innate immune activation and suggest a role for hCG-derived oligopeptides at the placenta that increases the risk of L. monocytogenes infections. http://repub.eur.nl/res/pub/19873/ 2010-03-01T00:00:00Z In its rare occurrence, Langerhans cell histiocytosis (LCH) is a dangerous but intriguing deviation of mononuclear phagocytes, especially dendritic cells (DCs). Clinically, the disease ranges from self-resolving or well manageable to severe and even fatal. LCH lesions in skin, bone, and other sites contain high numbers of cells with phenotypic features resembling LCs admixed with macrophages, T cells, eosinophils, and multinucleated giant cells. Here we review current progress in the LCH field based on two central questions: (i) are LCH cells intrinsically aberrant, and (ii) how does the lesion drive pathogenesis? We argue that LCH cells may originate from different sources, including epidermal LCs, tissue Langerin+ DCs, or mononuclear phagocyte precursors. Current and prospective in vitro and in vivo models are discussed. Finally, we discuss recent insights into plasticity of T-helper cell subsets in light of the lesion microenvironment. LCH continues to provide urgent clinical questions thereby inspiring innovative DC lineage research. http://repub.eur.nl/res/pub/19820/ 2010-01-01T00:00:00Z Neoplastic diseases of macrophages (M phi) and dendritic cells (DC), collectively called histiocytoses, are relatively rare. The etiology of most forms of histiocytosis is poorly understood, and the development of animal models is crucial for further research in this field. Previously, an animal model for malignant histiocytosis (MH), involving transformed histiocytic cells, has been generated by infecting mice with malignant histiocytosis sarcoma virus (MHSV). However, increased insight into the heterogeneity of M phi and DC, and the associated reappraisal of human proliferative diseases involving these cells inspired us to re-evaluate the mouse model. We analyzed spleen, bone marrow, and lymph nodes of susceptible mice at various time points after infection. From day 11 onwards, a heterogeneous population of cells, consisting of CD8 alpha(+) Langerin(+) DC, ER-MP58(+) CD11b(+) myeloid precursor cells, CD169(+) metallophilic M phi, and CD71(hi) erythroblasts, was affected by viral transformation. In different mice, these subsets expanded at different rates in different organs, causing a variable disease profile in terminal stages. Cell lines, which were generated from MHSV-transformed tumors, showed a DC-like morphology and phenotype, and appeared to be arrested in different stages of maturation. Upon injection into healthy mice, different preferential homing patterns were observed for the various cell lines, and the cells acquired distinct phenotypes depending on the organ of homing. This indicates that these transformed cells adapt to their microenvironment by switching between precursor, DC/Langerhans cell, and M phi phenotypes. Our results demonstrate that the MHSV model represents a heterogeneous neoplastic disease with characteristics of M phi/DC sarcomas. http://repub.eur.nl/res/pub/24085/ 2009-12-01T00:00:00Z The Gr-1 (RB6-8C5) Ab binds with high affinity to mouse Ly-6G molecules and to a lower extent to Ly-6C and has been widely used for cell depletion in infected or tumor-bearing mice. Here we found that Gr-1 treatment of BM cells in vitro and in vivo showed no depleting effects. The epitope recognized by the Gr-1 Ab overlapped with Ly-6G (1A8 Ab) but not Ly-6C (ER-MP20 Ab). In vitro the Gr-1 Ab transmitted signals via STAT-1, STAT-3 and STAT-5 into BM cells, similar to GM-CSF. In healthy mice injected with the Gr-1 Ab, the Ab remained attached to the surface ofmyeloid cells for at least four days. Gr-1 Ab induced myeloid cell expansion, upregulation of macrophage markers, but not the DC marker CD11c. Suppressor activity of two distinct Gr-1highand Gr-1lowexpressing BM-myeloid-derived suppressor cell subsets was transiently ablated by Gr-1 Ab injection. Depleting effects of Gr-1 Ab could only be observed on inflammatory Ly-6CintLy-6Ghighneutrophils from the peritoneal cavity, which occurred via apoptosis and was associated with the absence of Mcl-1 expression. Together, Gr-1 Ab induces signals leading to myelopoiesis and affects myeloid-derived suppressor cell activity, suggesting functional roles for Ly-6C/G molecules in macrophage differentiation and neutrophil apoptosis. http://repub.eur.nl/res/pub/16749/ 2009-09-01T00:00:00Z Type 1 diabetes (T1D) is an autoimmune disease in which a T-cell-mediated attack destroys the insulin-producing cells of the pancreatic islets. Despite insulin supplementation severe complications ask for novel treatments that aim at cure or delay of the onset of the disease. In spontaneous animal models for diabetes like the nonobese diabetic (NOD) mouse, distinct steps in the pathogenesis of the disease can be distinguished. In the past 10 years it became evident that DC and macrophages play an important role in all three phases of the pathogenesis of T1D. In phase 1, dendritic cells (DC) and macrophages accumulate at the islet edges. In phase 2, DC and macrophages are involved in the activation of autoreactive T cells that accumulate in the pancreas. In the third phase the islets are invaded by macrophages, DC and NK cells followed by the destruction of the beta-cells. Recent data suggest a role for a new member of the DC family: the plasmacytoid DC (pDC). pDC have been found to induce tolerance in experimental models of asthma. Several studies in humans and the NOD mouse support a similar role for pDC in diabetes. Mechanisms found to be involved in tolerance induction by pDC are inhibition of effector T cells, induction of regulatory T cells, production of cytokines and indoleamine 2,3-dioxygenase (IDO). The exact mechanism of tolerance induction by pDC in diabetes remains to be established but the intrinsic tolerogenic properties of pDC provide a promising, yet underestimated target for therapeutic intervention. http://repub.eur.nl/res/pub/25356/ 2009-08-01T00:00:00Z Human chorionic gonadotrophin (hCG) is a hormone produced during pregnancy and present at the implantation site and in the maternal blood. Pregnancy has been proposed to represent a controlled state of inflammation at an early stage at the implantation site and later, systemically extended to the maternal circulation. Earlier, we reported that hCG can inhibit the development of diabetes in NOD mice and LPS-induced septic shock in a murine model. We hypothesize that hCG can contribute to the reduction of inflammation by modifying Mφ function. Here, the TG-induced peritonitis model for inflammation was used to investigate the effect of hCG on cytokine production and cell recruitment in vivo. hCG pretreatment in TG-induced peritonitis increased the number of peritoneal cells, especially PMN and monocytes, compared with mice injected with TG only. This increased cell number was partially explained by increased cell survival induced by hCG. Despite the cellular infiltrate, hCG pretreatment decreased i.p. TNF-α, IL-6, PTX3, CCL3, and CCL5 levels. By depleting peritoneal resident Mφ using clodronate liposomes prior to the application of hCG and the TG trigger, we established that Mφ are the main responsive cells to hCG, as the suppressed TNF-α and IL-6 production and increased PMN influx are abolished in their absence. Together, these data suggest that hCG contributes to the controlled inflammatory state of pregnancy by regulating Mφ proinflammatory function. http://repub.eur.nl/res/pub/25446/ 2009-06-15T00:00:00Z Keratinocyte growth factor (KGF) protects mice from acute graft-vs-host disease and graft rejection by cytoprotective and yet incompletely understood immunological mechanisms. Recently, we showed that administration of KGF induces selective peripheral expansion of CD4+Foxp3+regulatory T cells (Treg). In this study, we set out to assess whether the peripheral expansion of Treg accounts for the immunomodulatory effects of KGF after bone marrow (BM) transplantation. To exclude potentially confounding cytoprotective and thymopoietic effects of KGF, we applied KGF to congenic wild-type mice that served as T cell provider mice for T and B cell-deficient RAG-1-/-mice that were subsequently transplanted with allogeneic BM. Treatment of congenic T cell provider mice with KGF significantly improved engraftment and reduced graft rejection in BMT recipients. CD4+Foxp3+Treg remained increased for 4 wk, while expansion of congenic CD3+T cells was inhibited. To assess a causal relationship between expansion of Treg and improved BM engraftment, congenic Scurfy mice, which lack Foxp3+Treg, served as T cell provider mice and were treated with KGF. KGF-treatment of Scurfy mice did not affect engraftment nor did it inhibit the expansion of congenic T cells. These data demonstrate that administration of KGF to the T cell provider mice improves engraftment of allogeneic BM through a CD4+Foxp3+Treg-dependent mechanism. Copyright http://repub.eur.nl/res/pub/25357/ 2009-06-01T00:00:00Z Cells of the myeloid lineage at various stages of maturity can differentiate into multinucleated osteoclasts. Yet, it is unclear which developmental stages of this lineage are more prone to become osteoclasts than others. We investigated the osteoclastogenic potential of three successive stages of myeloid development isolated from mouse bone marrow. Early blasts (CD31hi/Ly-6C-), myeloid blasts (CD31+/Ly- 6C+), and monocytes (CD31-/Ly-6Chi), as well as unfractionated marrow cells, were cultured in the presence of M-CSF and receptor activator of NF-κB ligand (RANKL), and the differentiation toward multinucleated cells and their capacity to resorb bone was assessed. Myeloid blasts developed rapidly into multinucleated cells; in only 4 days, maximal numbers were reached, whereas the other fractions required 8 days to reach maximal numbers. Bone resorption was observed after 6 (myeloid blasts and monocyte-derived osteoclasts) and 8 (early blastderived osteoclasts) days. This difference in kinetics in osteoclast-forming capacity was confirmed by the analysis of osteoclast-related genes. In addition, the myeloid blast fraction proved to be most sensitive to M-CSF and RANKL, as assessed with a colony-forming assay. Our results show that osteoclasts can develop from all stages of myeloid differentiation, but myeloid blasts are equipped to do so within a short period of time. http://repub.eur.nl/res/pub/32590/ 2009-05-01T00:00:00Z Bone marrow (BM)-derived endothelial progenitor cells (EPC) contribute to vascular maintenance by participating in angio- genesis, re-endothelialization, and remodeling. Myeloid progenitor cells in the BM are functionally and quantitatively an important precursor pool for cells that contribute to these processes. However, these precursor pools in the BM also give rise to important effector cells of the innate immune system, such as macrophages and dendritic cells. We hypothesized that the disturbed repair responses that are being observed in diabetes mellitus are also related to an effect on functional and differentiation characteristics at the level of this bone marrow precursor pool. Indeed, we observed that bone marrow differentiation cultures for EPC, macrophages (Mph), or dendritic cells (DC) from hyperglycemic BM yielded 40% fewer EPC and 50% more Mph compared with control BM. These changes were directly related to the hemoglobin A1Clevels of the donor mice. BM-derived DC numbers were not affected by hyperglycemia.The composition of the BM was not altered; in particular, the numbers of CD31+/Ly6C+cells, which serve as common progenitors for EPC,Mph,and DC,were unaffected. In addition,BM-derived EPC from hyperglycemic mice were less angiogenic and more proinflammatory in regards to endocytosis, T-cell activation, and interleukin 12 production. HMG-CoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase inhibition by statin supplementation of the culture medium counteracted these hyperglycemia-induced changes. Our study results show that hyperglycemia alters the differentiation fate of BM precursor cells, reducing the potential to generate vascular regenerative cells and favoring the development of proinflammatory cells. http://repub.eur.nl/res/pub/29760/ 2008-04-01T00:00:00Z The pregnancy hormone human chorionic gonadotropin (hCG) has been suggested to play an immunoregulatory role in addition to its endocrine function, thus contributing to the prevention of fetal rejection. We hypothesized that hCG is involved in the maternal-fetal immune tolerance by the regulation of dendritic cell (DC) function. Therefore, we studied the effect of hCG on DC maturation. Upon hCG treatment in combination with LPS, mouse bone marrow-derived DC (BMDC) increased the ratio of IL-10:IL-12p70, down-regulated TNF-α, and decreased antigen-specific T cell proliferation. Addition of hCG together with LPS and IFN-γ blocked MHC class II up-regulation, increased IL-10 production, and decreased the antigen-specific T cell proliferation by DC. Splenic DC showed similar results. Upon hCG treatment, IDO mRNA expression and its metabolite kynurenine were increased by LPS- and IFN-α-stimulated DC, suggesting its involvement in the decreased T cell proliferation. To study the effect of hCG on DC differentiation from precursors, BMDC were generated in the continuous presence of hCG. Under this condition, hCG decreased cytokine production and the induction of T cell proliferation. These data are suggestive for a contribution of hCG to the maternal-fetal tolerance during pregnancy by modifying DC toward a tolerogenic phenotype. http://repub.eur.nl/res/pub/36180/ 2007-10-01T00:00:00Z Human chorionic gonadotropin (hCG) is a placental glycoprotein, mainly secreted by trophoblasts during pregnancy. Its function in endocrine regulation has been well documented, but its immunological role is still largely unclear. For a successful pregnancy, an effective innate immunity is needed to protect the mother and fetus against infection, while maintaining tolerance against the paternal antigens of the fetus. The aim of this study was to investigate the effect of hCG on the function of macrophages (Mφ), which are major players in the innate response. hCG treatment of IFN-γ-primed Mφ resulted in increased production of NO, reactive oxygen species, IL-6 and IL-12p40, and enhanced phagocytosis of apoptotic cells. hCG treatment did not affect the induction of allogeneic T cell proliferation by IFN-γ-primed Mφ. The observed effects were receptor-mediated and involved the protein kinase A signaling pathway, as indicated by blocking studies using specific inhibitors. In vivo thioglycollate-elicited Mφ also exhibited increased phagocytic ability upon IFN-γ activation and hCG treatment. In conclusion, hCG enhances Mφ functions involved in innate immunity, while the capacity to stimulate allogeneic T cells remains unchanged. http://repub.eur.nl/res/pub/35539/ 2007-03-01T00:00:00Z We previously found that low shear stress (LSS) induces atherosclerotic plaques in mice with increased lipid and matrix metalloproteinase content and decreased vascular smooth muscle and collagen content. Here, we evaluated the role of chemokines in this process, using an extravascular device inducing regions of LSS, high shear stress, and oscillatory shear stress (OSS) in the carotid artery. One week of shear stress alterations induced expression of IFN-γ-inducible protein-10 (IP-10) exclusively in the LSS region, whereas monocyte chemoattractant protein-1 (MCP-1) and the mouse homolog of growth-regulated oncogene α (GRO-α) were equally upregulated in both LSS and OSS regions. After 3 weeks, GRO-α and IP-10 were specifically upregulated in LSS regions. After 9 weeks, lesions with thinner fibrous caps and larger necrotic cores were found in the LSS region compared with the OSS region. Equal levels of MCP-1 expression were observed in both regions, while expression of fractalkine was found in the LSS region only. Blockage of fractalkine inhibited plaque growth and resulted in striking differences in plaque composition in the LSS region. We conclude that LSS or OSS triggers expression of chemokines involved in atherogenesis. Fractalkine upregulation is critically important for the composition of LSS-induced atherosclerotic lesions. http://repub.eur.nl/res/pub/13644/ 2005-04-01T00:00:00Z Dendritic cells (DC) and macrophages (Mphi) are present in high numbers in the pancreas of the non-obese diabetic (NOD) mouse during the diabetogenic process from very early stages onwards. In this study, we used clodronate-loaded liposomes to mediate the temporary systemic depletion of these phagocytic cells and monocytic precursors in order to modulate the pancreatic inflammation. Two intraperitoneal injections given with a 2-day interval to 8-week-old NOD mice depleted monocytes from the circulation and monocytes, DC and Mphi from the spleen within the first days after the injections. Monocytes, DC and Mphi reappeared in the circulation and the spleen within one week and had an unchanged phenotype and antigen presenting function. Interestingly, this treatment caused a delayed disappearance (7-21 days postinjection) of DC and Mphi from the endocrine pancreas at a time when monocytes, DC and Mphi had already repopulated the circulation and the spleen. The depletion of DC and Mphi from the endocrine pancreas was accompanied by a total disappearance of lymphocytes from the pancreas. DC, Mphi and lymphocytes reappeared in the pancreatic inflammatory infiltrates in treated mice from 28 days postdepletion onwards. Importantly, the treatment significantly postponed the onset of diabetes, leading to a strongly decreased incidence by 35 weeks of age. Taken together, our data show an essential role of phagocytic cells, that is, DC and Mphi, in the recruitment of lymphocytes to the pancreatic islets in NOD mice. http://repub.eur.nl/res/pub/10359/ 2004-01-01T00:00:00Z The NOD mouse spontaneously develops autoimmune diabetes. Dendritic cells (DC) play a crucial role in the autoimmune response. Previous studies have reported a defective DC generation in vitro from the NOD mouse bone marrow (BM), but a deviated development of myeloid precursors into non-DC in response to GM-CSF was not considered. In this study, we demonstrate several abnormalities during myeloid differentiation of NOD BM precursors using GM-CSF in vitro. 1) We found reduced proliferation and increased cell death in NOD cultures, which explain the previously reported low yield of DC progeny in NOD. Cell yield in NOR cultures was normal. 2) In a detailed analysis GM-CSF-stimulated cultures, we observed in both NOD and NOR mice an increased frequency of macrophages, identified as CD11c(+)/MHCII(-) cells with typical macrophage morphology, phenotype, and acid phosphatase activity. This points to a preferential maturation of BM precursors into macrophages in mice with the NOD background. 3) The few CD11c(+)/MHCII(high) cells that we obtained from NOD and NOR cultures, which resembled prototypic mature DC, appeared to be defective in stimulating allogeneic T cells. These DC had also strong acid phosphatase activity and elevated expression of monocyte/macrophage markers. In conclusion, in this study we describe a deviated development of myeloid BM precursors of NOD and NOR mice into macrophages and macrophage-like DC in vitro. Potentially, these anomalies contribute to the dysfunctional regulation of tolerance in NOD mice yet are insufficient to induce autoimmune diabetes because they occurred partly in NOR mice. http://repub.eur.nl/res/pub/10120/ 2003-01-01T00:00:00Z The lineage relationship of dendritic cells (DC) with other hematopoietic cell types has been studied extensively, resulting in the identification of different bone marrow (BM) progenitors that give rise to distinct DC types. However, the identity of the different maturation stages of DC precursors in the BM remains unclear. In this study we define the in vivo developmental steps of the myeloid DC lineage in mouse BM. To this end, BM cells were separated according to their expression of CD31 (ER-MP12), Ly-6C (ER-MP20) and ER-MP58 antigens, and stimulated to develop into myeloid DC, using granulocyte macrophage colony stimulating factor as a specific growth factor. DC developed from three BM subpopulations: ER-MP12(hi)/20(-) (early blast cells), ER-MP12(+)/20(+) (myeloid blasts) and ER-MP12(-)/20(hi) (monocytes). The kinetic and phenotypic features of DC developing in vitro indicate that the three populations represent successive maturation stages of myeloid DC precursors. Within the earliest ER-MP12(hi)/20(-) population, DC precursors exclusively occurred in the myeloid-restricted ER-MP58(hi) subset. By using switch cultures, we show that these BM precursor subpopulations, when stimulated to develop into macrophages using macrophage colony stimulating factor, retain the ability to develop into myeloid DC until advanced stages of maturation. Together, these findings support a common ER-MP12/20-defined differentiation pathway for both macrophages and myeloid DC throughout their BM development. http://repub.eur.nl/res/pub/8183/ 2002-01-01T00:00:00Z Airway dendritic cells (DCs) are held responsible for inducing sensitization to inhaled antigen, leading to eosinophilic airway inflammation, typical of asthma. However, less information is available about the role of these cells in ongoing inflammation. In a mouse model of asthma, sensitization to ovalbumin (OVA) was induced by intratracheal injection of myeloid OVA-pulsed DCs. Upon OVA aerosol challenge and induction of eosinophilic airway inflammation in sensitized mice, there was a time-dependent and almost 100-fold increase in the number of MHCII(+) CD11b(+) CD11c(+) endogenous airway DCs as well as CD11b(+) blood DCs. The mechanism of this increase was studied. Adoptive transfer experiments demonstrated that accumulation of airway DCs was not due to reduced migration to the mediastinal lymph nodes. Rather, the massive increase in airway and lymph node DCs was supported by an almost 3-fold expansion of myeloid CD31(hi)Ly-6C(neg) hematopoietic precursor cells in the bone marrow (BM). There was no change in any of the other 5 populations revealed by CD31/Ly-6C staining. When these CD31(hi)Ly-6C(neg) BM precursors were sorted and grown in granulocyte macrophage-colony-stimulating factor, they differentiated into MHCII(+) CD11c(+) DCs. The same CD31(hi)Ly-6C(neg) precursors also expressed the eotaxin receptor CCR3 and differentiated into eosinophils when grown in interleukin 5. Serum levels of eotaxin were doubled in mice with inflammation. These findings in an animal model of asthma suggest that the BM increases its output of myeloid precursors to meet the enhanced demand for DCs and eosinophils in inflamed airways. http://repub.eur.nl/res/pub/9086/ 1999-01-01T00:00:00Z Mice homozygous for the disruption of the PU.1 (Spi-1) gene do not produce mature macrophages. In determining the role of PU.1 in macrophage differentiation, the present study investigated whether or not there was commitment to the monocytic lineage in the absence of PU.1. Early PU.1-/- myeloid colonies were generated from neonate liver under conditions that promote primarily macrophage and granulocyte/macrophage colonies. These PU.1-/- colonies were found to contain cells with monocytic characteristics as determined by nonspecific esterase stain and the use of monoclonal antibodies that recognize early monocyte precursors, including Moma-2, ER-MP12, ER-MP20, and ER-MP58. In addition, early myeloid cells could be grown from PU.1-/- fetal liver cultures in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF). Similar to the PU.1 null colonies, the GM-CSF-dependent cells also possessed early monocytic characteristics, including the ability to phagocytize latex beads. The ability of PU.1-/- progenitors to commit to the monocytic lineage was also verified in vivo by flow cytometry and cytochemical analysis of primary neonate liver cells. The combined data shows that PU.1 is absolutely required for macrophage development after commitment to this lineage. http://repub.eur.nl/res/pub/8790/ 1998-01-01T00:00:00Z In the normal mouse spleen, two distinct populations of dendritic cells (DC) are present that differ in microanatomical location. The major population of marginal DC is found in the "marginal zone bridging channels" and extends into the red pulp. The interdigitating cells (IDC) are localized in the T cell areas in the white pulp. The aim of the present study was to characterize these two splenic DC populations with regard to their phenotype, in vivo phagocytic function, and turnover. Both marginal DC and IDC are CD11c+ and CD13+, but only IDC are NLDC-145+ and CD8alpha+. Notably, both populations, when freshly isolated, express the macrophage markers F4/80, BM8, and Mac-1. To study the phagocytic capacity of these cells, we employed the macrophage "suicide" technique by injecting liposomes loaded with clodronate i.v. Marginal DC, but not IDC, were eliminated by this treatment. Phagocytosis of DiI-labeled liposomes by DC confirmed this finding. The two DC populations differed significantly with regard to their turnover rates, as studied in a transgenic mouse model of conditional depletion of DC populations with high turnover. In these mice, marginal DC were completely eliminated, but the IDC population remained virtually intact. From these data we conclude that the marginal DC population has a high turnover, in contrast to the IDC population. Taken together, the present results indicate that marginal DC and IDC represent two essentially distinct populations of DC in the mouse spleen. They differ not only in location, but also in phenotype, phagocytic ability, and turnover.