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Biomedical subjects

R H Beelen

Publications and source records attributed to R H Beelen.

At least 19 recordsLinked to original sources
PubMed1999

Regulation of CD 163 on human macrophages: cross-linking of CD163 induces signaling and activation.

CD163 is a member of the group B scavenger receptor cysteine-rich (SRCR) superfamily. This study describes aspects of the tissue distribution, the regulation of expression, and signal transduction after cross-linking of this receptor at the cell surface of macrophages. CD163 showed an exclusive expression on resident macrophages (e.g., red pulp macrophages, alveolar macrophages). The expression was inducible on monocyte-derived macrophages by glucocorticoids but not by interleukin-4 (IL-4), granulocyte-macrophage colony-stimulating factor (GM-CSF), and interferon-gamma. The combination of IL-4 or GM-CSF with glucocorticoids resulted in a further increase. Subcellular analysis of alveolar macrophages by immunoelectron microscopy showed a plasma membrane localization of the antigen. Cross-linking of CD163 with monoclonal antibody induced a protein tyrosine kinase-dependent signal that resulted in (1) slow-type calcium mobilization, (2) inositol triphosphate production, and (3) secretion of IL-6 and GM-CSF. The data suggest a function for the SRCR-superfamily receptor CD163 in the regulation of inflammatory processes by macrophages.

Animals↗
PubMed1999

Impaired leukocyte phagocytosis in patients undergoing hemihepatectomy for liver metastases.

Patients undergoing partial hepatectomy have an increased susceptibility to infection. To investigate whether this increased risk is related to impaired leukocyte function, we studied polymorphonuclear leukocyte (PMN) phagocytosis in patients undergoing a hemihepatectomy because of liver metastasis (LM, n = 11) and in patients undergoing major abdominal surgery because of abdominal malignancy (AM, n = 8). Eight healthy volunteers (HVs) served as controls. Leukocyte suspensions were incubated with fluorescein isothiocyanate-labeled Staphylococcus aureus, and phagocytosis was measured by flow cytometry. Preoperative PMN phagocytosis, in the presence of autologous plasma, was significantly less in patients with LM compared with patients with AM or HVs. This impaired phagocytosis was potentially restored in the presence of normal plasma. The decreased phagocytic capacity of PMNs from patients with LM was not related to levels of known plasma opsonins or phenotypic changes of PMNs. Rather, it was related to a deficiency of unidentified plasma factors. After surgery, the phagocytic capacity of PMNs of patients with AM decreased by approximately 30%, which correlated with decreasing levels of immunoglobulin G and C3. In conclusion, patients with LM had a decreased PMN phagocytic capacity before surgery. This impairment in phagocytosis disappeared 1 week after surgery. We propose that the presence of LM leads to a deficiency of factor(s) in the blood that impairs PMN phagocytic capacity.

Case-Control Studies↗
PubMed1999

Immunological consequences of laparoscopic surgery, speculations on the cause and clinical implications.

BACKGROUND: Immune suppression is an established consequence of surgical stress and trauma. Postoperative changes in the systemic immune system are proportional to the degree of surgical trauma and subsequent immune suppression may be implicated in the development of infectious complications and tumor metastasis formation. Laparoscopic surgery reduces the magnitude of the operative trauma and is thought to preserve postoperative immunological defenses. METHODS: Relevant literature concerning postoperative immune functions and laparoscopic surgery was reviewed and clinical implications are discussed. RESULTS: The influence of laparoscopic surgery on the postoperative systemic immune response is significantly less after laparoscopic cholecystectomy than with the conventional approach. Few immunological data are available concerning more advanced laparoscopic procedures. Various animal model studies of postoperative septic complications and tumor growth show that the postoperative preservation of the systemic immune response after laparoscopic surgery can have enormous clinical advantages. CONCLUSION: Laparoscopic surgery preserves the postoperative immunological defenses. In the future, this may imply a lower number of infections, less local recurrence and even fewer distant metastases. Prospective randomized studies are necessary to see whether these suspected advantages can be demonstrated in clinical practice.

Cholecystectomy, Laparoscopic↗
PubMed1999

Expression of MCP-1 by reactive astrocytes in demyelinating multiple sclerosis lesions.

The pathology of multiple sclerosis (MS) is characterized by breakdown of the blood-brain barrier (BBB), accompanied by infiltration of macrophages and T lymphocytes into the central nervous system (CNS). The migration of these cells into the CNS parenchyma may be partly regulated by chemokines. The aim of this study was therefore to investigate the cellular localization of the potent monocyte- and T-cell-attracting chemokine monocyte chemoattractant protein (MCP)-1 by immunohistochemistry on postmortem brain tissue from MS and normal control cases. Brain tissue samples of six MS patients and four patients without a history of brain disease were neuropathologically classified according to characteristic (immuno)histochemical staining patterns. Frozen tissue sections of active demyelinating MS lesions, chronic active demyelinating MS lesions, and normal control brain were immunohistochemically stained with a monoclonal antibody directed against MCP-1. In active demyelinating MS lesions as well as in chronic active MS lesions, reactive hypertrophic astrocytes were strongly immunoreactive for MCP-1, whereas perivascular and parenchymal foamy macrophages did not express MCP-1 protein. These results suggest a significant role for the beta-chemokine MCP-1, synthesized in vivo by reactive hypertrophic astrocytes, in the recruitment and activation of myelin-degrading macrophages and thereby contributing to the evolution of MS lesions.

Adult↗
PubMed1999

Glucocorticoids modulate the development of dendritic cells from blood precursors.

Dendritic cells (DC) are professional antigen-presenting cells, capable of priming naive T cell responses. Glucocorticoids (GC) are frequently used in asthmatic patients. In this study we describe the effects of GC on the development and function of monocyte-derived DC (MoDC) in vitro and in vivo. Monocytes from healthy individuals were isolated and incubated with granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-4 for 6 days, to induce maturation into MoDC. To study the role of GC on DC differentiation in vitro cells were incubated with dexamethasone at different stages of MoDC development. At day 6 cells were characterized phenotypically by flow cytometry and functionally in an allogeneic mixed leucocyte reaction. To study the effect of GC in vivo patients with mild/moderate atopic asthma were selected. In one group no GC were used, whereas the other group used inhalation GC. MoDC from these patients were generated as described above and tested functionally. Incubation of MoDC or its peripheral blood precursors with dexamethasone decreased the accessory potency dose-dependently. The functional differences could not be explained by the changes in the expression of MHC II and the costimulatory molecules CD40 and CD86. The relevance of this mechanism was confirmed for the in vivo situation as well. MoDC from patients using inhalation GC showed a decreased accessory potency. These data suggest a modulatory effect of GC therapy at the level of the peripheral blood monocyte. The results indicate that GC influence DC development and function in vitro as well as in vivo.

Administration, Inhalation↗
PubMed1999

Infection of human endothelial cells with Staphylococcus aureus induces the production of monocyte chemotactic protein-1 (MCP-1) and monocyte chemotaxis.

Bacterial infection coincides with migration of leucocytes from the circulation into the bacterium-infected tissue. Recently, we have shown that endothelial cells, upon binding and ingestion of Staphylococcus aureus, exhibit proinflammatory properties including procoagulant activity and increased intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression on the cell surface, resulting in hyperadhesiveness, mainly for monocytes. The enhanced extravasation of monocytes to bacterium-infected sites is facilitated by the local production of chemotactic factors. From another study we concluded that the locally produced chemokine MCP-1 is important in the recruitment of monocytes to the peritoneal cavity in a model of bacterial peritonitis. In the present study we investigated whether cultured human endothelial cells after infection with bacteria produce and release MCP-1, which in turn stimulates monocyte chemotaxis. We observed that endothelial cells released significant amounts of MCP-1 within 48 h after ingestion of S. aureus. This was dependent on the number and the virulence of the bacteria used to infect the endothelial cells. The kinetics as well as the amount of MCP-1 released by S. aureus-infected endothelial cells differed markedly from that released by endothelial cells upon stimulation with IL-1beta. Supernatant from S. aureus-infected or IL-1beta-stimulated cells promoted monocyte chemotaxis which was almost entirely abrogated in the presence of neutralizing anti-MCP-1 antibody, indicating that most of the chemotactic activity was due to the release of MCP-1 into the supernatant. Our findings support the notion that endothelial cells can actively initiate and sustain an inflammatory response after an encounter with pathogenic microorganisms, without the intervention of macrophage-derived proinflammatory cytokines.

Cells, Cultured↗
PubMed1999

A prospective randomized study of the systemic immune response after laparoscopic and conventional Nissen fundoplication.

BACKGROUND: Laparoscopic techniques are thought to reduce the postoperative immunologic and metabolic changes of conventional operations. Until now, the only clinical data available were obtained from patients operated on for symptomatic gallstones; moreover, few studies were randomized. This randomized prospective study compares the systemic immune response after laparoscopic and conventional Nissen fundoplication. METHODS: Seventeen patients scheduled for Nissen fundoplication were randomly assigned to undergo either a laparoscopic or a conventional procedure. Postoperative inflammatory response was assessed by measuring the white blood cell count, C-reactive protein, and soluble tumor necrosis factor receptors p55 and p75. Postoperative immune function was assessed by measuring monocyte HLA-DR expression and the stress response was assessed by measuring plasma cortisol concentrations. RESULTS: Laparoscopic surgery resulted in significantly lower plasma CRP levels 1 day after surgery. Both approaches resulted in a significant decrease in HLA-DR expression within 2 hours after surgery. After the laparoscopic approach, postoperative expression was restored to preoperative values within 1 day after surgery. However, after conventional surgery HLA-DR expression remained suppressed and did not return to preoperative values until the fourth postoperative day. No significant differences between the 2 procedures were observed in white cell blood count, sTNFr-p55 and p75, nor in postoperative cortisol levels. CONCLUSIONS: Although both laparoscopic and conventional Nissen fundoplication result in an activation of the systemic immune response, this study suggests that this response could be less after the laparoscopic approach. The differences found may reflect a lower risk for postoperative infective complications.

Adult↗
PubMed1998

Milky spots in the greater omentum are predominant sites of local tumour cell proliferation and accumulation in the peritoneal cavity.

The role that milky spots in the greater omentum play in tumour cell spread in the peritoneal cavity is presently not fully understood. To study whether intraperitoneally injected tumour cells appear preferentially in milky spots of the greater omentum and to study the changes in the greater omentum, and especially in the cell population of milky spots after tumour cell infiltration, the following study was performed. A detailed temporal sequences of changes in morphology and cellular composition in milky spots of the greater omentum of Wag/Rij rats 5, 15, 30, 60 min, 2, 4, 8, 16, 24 h, 2, 4, 8 days and 2 and 4 weeks after intraperitoneal administration of 2.0 x 10(6) CC 531 tumour cells was investigated by light microscopy and electron microscopy (pre-embedding labelling). Our data showed that the milky spots in the greater omentum were the sites to which tumour cells migrated preferentially from the peritoneal cavity. The tumour cells infiltrated the milky spots and formed clusters within. The cellular population in milky spots reacted by a very rapid influx of young macrophages during the first hour and an increase of the total number of cells (P < 0.01). After 4 h tumour cells were also located on the greater omentum outside the area of the milky spots. Around these tumour cell deposits, new milky spots are formed, which increased the total number of milky spots. The cells present in milky spots are not capable of reversing the growth of tumours and finally a solid omental cake of tumour cells is formed.

Animals↗
PubMed1998

Functional and phenotypic differences of monocyte-derived dendritic cells from allergic and nonallergic patients.

BACKGROUND: Several studies suggest a role for dendritic cell in the pathogenesis of allergic disease. OBJECTIVE: The purpose of this study was to compare function and phenotype of monocyte-derived dendritic cells (MoDC) from allergic asthmatic patients and healthy control subjects. METHODS: MoDCs were developed by incubating adherent monocytes for 5 days with IL-4 and granulocyte-macrophage colony-stimulating factor. Phenotype was assessed with flow cytometry, and the antigen-presenting function was assessed with the allogeneic mixed leukocyte reaction and an autologous specific antigen presentation. RESULTS: The morphology of the MoDCs was characteristic for immature dendritic cells. MoDCs from allergic asthmatic patients showed phenotypic differences in the expression of HLA-DR, CD11b, and the high-affinity receptor for IgE. A clearly enhanced accessory potential of MoDCs from atopic asthmatic patients in the mixed leukocyte reaction was also shown. Moreover, house dust mite-specific T-cell proliferation was increased. CONCLUSION: This study suggests the involvement of dendritic cells in the pathogenesis of atopic asthma by an increased immunostimulatory capacity of MoDCs.

Antigen Presentation↗
PubMed1998

Chemokines produced by mesothelial cells: huGRO-alpha, IP-10, MCP-1 and RANTES.

Recently we showed the in vivo relevance of chemokines in cases of bacterial peritonitis in continuous ambulatory peritoneal dialysis (CAPD) patients. Mesothelial cells, the most numerous cells in the peritoneal cavity, are hypothesized to function as a main source of chemokine production. We investigated the time- and dose-dependent expression patterns of four chemokines by mesothelial cells at the mRNA and protein level in response to stimulation with physiological doses of proinflammatory mediators that are present at the site of bacterial inflammation. Besides the chemokines huGRO-alpha (attractant for neutrophils), MCP-1 and RANTES (monocyte attractants), the expression and production of IP-10 was analysed. Mesothelial cells were cultured and stimulated with either IL-1beta, tumour necrosis factor-alpha (TNF-alpha) or IFN-gamma or combinations of these. The time- and dose-dependent mRNA expression of the chemokines was determined by Northern blot analysis and the protein production by ELISA. It was concluded that mesothelial cells could indeed be triggered by the mentioned stimuli to induce mRNA and protein production (huGRO-alpha and IP-10) or to augment constitutive protein production (MCP-1). However, RANTES mRNA and protein production could only be induced in some cases and only in small amounts. The chemokine response of mesothelial cells was regulated differentially, depending on the stimulus and the chemokine measured. In distinct cases, combination of the stimuli led to synergy in mRNA expression and protein production. The presented in vitro data support our hypothesis that mesothelial cells in vivo are the main source of relevant chemokines in response to proinflammatory mediators, suggesting an important role for mesothelial cells in host defence.

Cells, Cultured↗
PubMed1998

Experimental models in peritoneal dialysis: a European experience.

BACKGROUND: The development of adequate animal models is important for the in vivo study of selected aspects of peritoneal dialysis (PD) that cannot be evaluated by an in vitro model, such as peritoneal membrane transport, the influence of local defense mechanisms, and for testing new osmotic agents and their biocompatibilities. METHODS: Our experience with animal models for PD, including the acute Stockholm model in non-uremic rats, the acute and chronic Amsterdam model in non-uremic rats, and the chronic Gent model in uremic rats, is described. RESULTS: The Stockholm model proved to be useful in understanding the normal physiology of peritoneal transport, and for testing new dialysis solutions and their biocompatibilities. It is a rather simple and inexpensive model, and thus is suitable for screening new solutions and additives. The Amsterdam model permits the study of chemokines and mesothelial cell regeneration in vivo, and is applied in a model of chronic peritonitis. The results of the Gent model suggest that chronic peritoneal dialysis in uremic rats is feasible for at least eight weeks. This model is, however, very laborious, time consuming, and expensive. CONCLUSION: Further improvement of the technique and increase of the dialysis dose should result in a better and more realistic model for peritoneal dialysis. It is hoped that in the future these models will be useful to test the effects of long-term intraperitoneal application of different dialysis solutions and additives in uremic animals.

Animals↗
PubMed1998

Talc-induced inflammation in the pleural cavity.

Talc administration into the pleural cavity induces pleurodesis. To obtain further insight into the inflammatory process that causes pleurodesis, the cellular kinetics in the pleural space after the administration of talc was studied, along with its relation to chemokine concentrations in the pleural fluid. Thirteen consecutive patients with idiopathic spontaneous pneumothorax and eight patients with malignant pleural effusions received talc pleurodesis. The first group was treated with talc poudrage, whereas the second group was treated with talc slurry. Pleural fluids were isolated before talc administration as well as 3, 6, 24, 48 and 72 h afterwards. The talc induced a rapid polymorphonuclear neutrophil (PMN) influx followed by an accumulation of macrophages. In addition, increased production of interleukin (IL)-8 and monocyte chemotactic protein (MCP)-1 was observed. The talc-induced PMN influx reached its maximum after 3-24 h, and was related to the IL-8 concentration. In contrast, the MCP-1 was not related to the macrophage accumulation. Talc-induced inflammation in patients with idiopathic spontaneous pneumothorax and malignant pleural effusion is characterized by an influx of polymorphonuclear neutrophils related to interleukin-8, followed by an accumulation of monocytes.

Adult↗
PubMed1998

Effect of peritoneal dialysis fluid measured in vivo in a rat-model of continuous peritoneal dialysis.

To study the long-term effects of dialysis fluids on the peritoneal cavity, an in vivo model for continuous peritoneal dialysis in rats was developed. Mini vascular access ports were implanted subcutaneously in the neck of the rats and an attached catheter was instilled into the peritoneal cavity. Rats were injected daily with 10 mL of standard 3.86% Dianeal or saline for a period up to 12 weeks. In the peritoneal cavity an initial increase in total cells was observed after 4 weeks of fluid instillation. This had declined after 12 weeks. A similar trend was also seen for macrophage and neutrophil numbers, whereas the percentage of lymphocytes kept increasing in time. An effect of fluid instillation was observed on the density and the morphology of the mesothelial monolayer of the rats. A higher density of cells was observed after 12 weeks, and foci of young mesothelial cells within activated mesothelium were found. The results show that the rat model presented can be compared with the situation in the peritoneal cavity of continuous ambulatory peritoneal dialysis (CAPD) patients, and therefore is suitable for intervention studies.

Animals↗
PubMed1997

Ontogeny of milky spots in the human greater omentum: an immunochemical study.

BACKGROUND: Milky spots in the human greater omentum are preformed specific accumulations of primarily macrophages within the stroma of the greater omentum. To obtain a better understanding of milky spots in the human greater omentum, the development and the earliest forms of milky spots in the human greater omentum were studied, with special attention to the macrophage population. METHODS: Specimens of human greater omentum were obtained from fetuses of 20 to 40 weeks gestation and one newborn three days old (n = 6). Using mature macrophages (RFD 7), activated macrophages (RFD 1), B-lymphocytes (CD 22), and T-lymphocytes (CD 2), and immunoperoxydase labeling, the percentage of these cells in developing milky spots and the development of milky spots were studied by light microscopy. A time-dependent increase in the percentage of positive staining cells and the size of clusters was analyzed using the non-parametric Spearman rank correlation test. RESULTS: Small accumulations of cells with about 50% monocytes/macrophages were present at 20 weeks of gestation. With increasing gestational age the number of clusters of cells increased significantly (P < 0.01) as well as their size (P < 0.01). Starting at 29 weeks, vascularized clusters of cells were seen; true milky spots were present at 35 weeks. A significant (P < 0.05) increase in the percentage of mature macrophages was found in developing milky spots, whereas no activated macrophages were seen. The percentage of B-lymphocytes and T-lymphocytes found in the clusters of cells and milky spots increased significantly (P < 0.05) but did not exceed 10% of the total number of cells. CONCLUSIONS: From our data it can be concluded that milky spots are specific structures in the greater omentum formed between the 20th and 35th week of gestation. Further, we concluded that immature cells (promonocytes) mature locally in developing milky spots.

Cell Aggregation↗
PubMed1997

A functional study on the migration of human monocytes to human leukemic cell lines and the role of monocyte chemoattractant protein-1.

In the present study the migration of human monocytes towards the supernatants of five different human myeloid leukemic cell lines, four different human lymphatic leukemic cell lines and blasts derived from three different patients with acute myeloid leukemia (AML) was studied and the role of monocyte chemoattractant protein (MCP)-1 was established with an ELISA assay. Large differences in migration of monocytes towards the leukemic cell supernatants were shown (variation of approximately 10 to 150% compared to positive control), but high amounts of monocyte migration was always restricted to myeloid leukemic cells (cell lines or patient blasts). MCP-1 turned out to play a major role in the migration, firstly since there was a direct correlation between the amount of migration and the concentration of MCP-1 in the supernatants, and secondly since the addition of anti-hMCP-1 was able to inhibit migration to background level in all cases. Cytotoxicity experiments with a MTT test using MCP-1-stimulated monocytes against two human myeloid leukemic cell lines showed no increase in cell death compared to unstimulated monocytes. It is concluded that monocyte migration towards leukemic cells is restricted to the myeloid lineage and is regulated by MCP-1, which is produced in different amounts by the leukemic cells. Besides, MCP-1 does not increase the direct toxic effects of monocytes on leukemic cells.

Cell Culture Techniques↗
PubMed1997

Granulocyte macrophage colony stimulating factor pretreatment induces an increase of rat Kupffer cells with enhanced cytotoxicity in vitro and prevention of tumor outgrowth in vivo.

Male Wag rats were pretreated for 7 days with 1000 U/ml recombinant murine granulocyte macrophage colony stimulating factor (rmGM-CSF). Rat Kupffer cells (KC) were isolated by a enzymatic method. We injected decreasing numbers of CC531 tumor cells in the portal system. Mean KC yield increased from 1.5 +/- 0.2 to 2.2 +/- 0.2 (p < 0.05). Mean percentage of KC-mediated cytotoxicity against CC531 increased from 20.0 +/- 0.5 to 42 +/- 1.0 after rmGM-CSF (p < 0.05). At 1 x 10(5) CC531 tumor cells we demonstrated prevention of formation of small foci of CC52+ tumor cells. We demonstrate increased isolated KC with enhanced cytotoxic capacity after rmGM-CSF. rmGM-CSF induced prevention of minimal residual disease in the rat liver.

Animals↗
PubMed1997

Production of IL-1 beta and TNF-alpha by peritoneal macrophages depends on the bacterial species and the inoculum.

Peritoneal macrophages (PMs) are very potent producers of proinflammatory stimuli, such as interleukin (IL)-1 beta and tumor necrosis factor (TNF)-alpha. After contact with invading micro-organisms, PMs produce different cytokines, both pro- and anti-inflammatory. Therefore, they are crucial in the regulation of inflammatory events. The aim of this study was to investigate whether the production of IL-1 beta and TNF-alpha is dependent on the bacterial species used. PMs were harvested from spent peritoneal dialysis effluent and subsequently stimulated with five strains of bacteria in two different concentrations. After 24 hours of stimulation, supernatants were harvested and analyzed for both IL-1 beta and TNF-alpha content. IL-1 beta was measured with a commercial ELISA, and TNF-alpha was determined with a bioassay. Both the IL-1 beta and the TNF-alpha production were species-dependent. One strain of Staphylococcus aureus and one strain of Staphylococcus epidermidis induced a markedly higher response in both IL-1 beta and TNF-alpha than the other species. This response was also dose-dependent, and this holds true for all species. In conclusion, the IL-1 beta and TNF-alpha response by PMs is both species- and dose-dependent.

Dialysis Solutions↗