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G Hetland

Publications and source records attributed to G Hetland.

At least 19 recordsLinked to original sources
PubMed2001

Leptin does not influence the IgE response to ovalbumin in mice.

Leptin is important for maintenance of the body's energy homeostasis and it also increases Th1 and suppresses Th2 cytokine production. We have investigated the effect of leptin on the allergic immune response to the model allergen ovalbumin (OA) by using the popliteal lymph node assay (PLNA) and serum antibody determination in mice. Mice were injected with either leptin i.v. plus OA in one hind footpad, or leptin or OA alone. A booster dose of leptin was given twice and of OA once and the animals were exsanguinated on experimental day 19 when the PLNs also were removed. End-point measurements were serum levels of IgE, IgG1, and IgG2a anti-OA and weight and cell number of the excised PLNs. Leptin given i.v. with the protocol employed altered neither the cellular PLN response nor the specific serum IgE, IgG1, or IgG2a anti-OA levels compared with the group given OA without leptin. Our data indicate that systemic administration of leptin neither suppresses nor enhances the Th2-dependent antibody responses in the present mouse model.

Allergens↗
PubMed2001

Effects of C5a and FMLP on interleukin-8 production and proliferation of human umbilical vein endothelial cells.

Interleukin-8 (IL-8), C5a and N-formyl-methionyl-leucyl-phenylalanine (fMLP) are chemotactic peptides with predominant effects on leukocytes during inflammation. With emphasis on C5a we studied the regulation of the production of IL-8 by human umbilical vein endothelial cells (HUVEC) in vitro. Primary HUVEC cultures were incubated with IL-1alpha, TNFalpha, C5a and fMLP for 24 h and 48 h prior to measurement of IL-8 in supernatants of the cells by an enzyme immunoassay. Whereas IL-1alpha and TNFalpha significantly increased the levels of IL-8, C5a decreased the IL-8 production after 48 h. In addition, the ability of IL-1alpha, TNFalpha, C5a, fMLP and IL-8 to induce cell proliferation was compared by means of a 3H-thymidine incorporation assay. In contrast with IL-1alpha and TNFalpha, both C5a and fMLP increased cell proliferation of HUVEC. This increase occurred with increasing concentrations of C5a contrary to IL-8, which showed increased cell proliferation at low, but not high IL-8 concentrations.

Cell Division↗
PubMed2001

Detection of mRNA for the terminal complement components C5, C6, C8 and C9 in human umbilical vein endothelial cells in vitro.

Human umbilical vein endothelial cells (HUVEC) have previously been shown to synthesize the functional terminal pathway of complement based on the detection by radioimmunoassay of the terminal complement complex (TCC) on coincubated agarose beads. In addition, C7 secretion by these cells in amounts comparable to C3, as well as C7 mRNA, has recently been demonstrated. However, it has not been possible to detect C5-6 and C8 in the fluid phase, and only trace amounts of soluble C9. Against this background we examined whether mRNA for the remaining terminal complement factors was present in HUVEC. By the use of reverse transcription (RT)-polymerase chain reaction (PCR) and Northern blot the presence of mRNA for complement factors C5, C6, C8 and C9 was demonstrated.

Base Sequence↗
PubMed2000

The fungal cell wall component beta-1,3-glucan has an adjuvant effect on the allergic response to ovalbumin in mice.

The polyglucose beta-1,3-D-glucan is a major structural component of the cell wall of yeasts and fungi. In the present study, the adjuvant activity of beta-1,3-glucan from the fungus Sclerotinia sclerotiorum (SSG) on the response to the model allergen ovalbumin (OA) was studied, using the popliteal lymph node assay (PLNA) in BALB/c mice. The adjuvant activity on the local cellular response was determined by measuring the weight, cell number, and proliferation of the extracted PLNs. The levels of OA-specific immunoglobulin (Ig)E, IgG1, and IgG2a in serum were measured by enzyme-linked immunosorbent assay (ELISA). Groups of 8 mice were given either SSG + OA, SSG alone, or OA alone on d 0. Thereafter they were exsanguinated on d 20, or reinjected with OA on d 21, before exsanguination on d 26 or 33. Only on d 26 was SSG + OA found to significantly increase the PLN weight and cell numbers, but not cell proliferation (thymidine incorporation), compared with OA or SSG alone. SSG + OA was also found to significantly increase both the anti-OA IgE and IgG1 levels on d 20, 26, and 33 compared to OA alone. Compared to SSG alone, SSG + OA increased the OA-specific IgE and IgG 1 levels significantly on d 26 and 33, but not on d 20. A similar increase was not found for IgG2a. Our results show that beta-1,3-D-glucan provides a clear Th2-dependent (allergic) immune response to OA, indicated by elevated levels of IgE and IgG1 and not IgG2a, in the mouse model used.

Adjuvants, Immunologic↗
PubMed2000

Protective effect of Plantago major L. Pectin polysaccharide against systemic Streptococcus pneumoniae infection in mice.

The antibacterial effect of a soluble pectin polysaccharide, PMII, isolated from the leaves of Plantago major, was examined in inbred NIH/OlaHsd and Fox Chase SCID mice experimentally infected with Streptococcus pneumoniae serotype 6B. Serotype 6B is known to give a more protracted infection when injected intraperitoneally into susceptible mice than more virulent serotypes like type 4. PMII was administered i.p. either once 3 days before challenge or once to thrice from 3 to 48 h after challenge. The number of bacteria in blood and the mouse survival rate were recorded. Pre-challenge administration of PMII and also lipopolysaccharide (LPS), included as a control, gave a dose-dependent protective effect against S. pneumoniae type 6B infection. However, injection of PMII after establishment of the infection in NIH/OlaHsd mice had no effect. The data demonstrate that, firstly, the polysaccharide fraction PMII from P. major protects against pneumococcal infection in mice when administered systemically prechallenge, and secondly that the protective effect is owing to stimulation of the innate and not the adaptive immune system.

Animals↗
PubMed2000

Concentrations of leucocyte-associated chemotaxin C5a correlate with the mobilisation of polymorphonuclear leucocytes during operations for rectal cancer.

OBJECTIVE: To describe the profile of potential chemotaxins C5a, interleukin 8 and tumour-necrosis factor alpha, and the peripheral blood leucocyte (PBL) response in five patients having uncomplicated operations for rectal cancer. DESIGN: Prospective study. SETTING: University hospital, Norway. SUBJECTS: Five patients, four men and one woman, median age 66 years (range 48-77) who were operated on for rectal cancer. INTERVENTION: Four had low anterior resections and total mesorectal excision (TME) and one patient had a diverting end sigmoidostomy because of local perirectal spread of the cancer and liver metastases. Blood samples were taken at the start of the operation; peroperatively after 1, 2, and 3 hours; postoperatively at 5, 8, and 24 hours, for analysis of potential chemotaxins. RESULTS: The number of PBL tripled between the start and end of the operation and declined to a slightly lower plateau between 5 and 24 hours. Peroperatively, the association of C5a with PBL increased six-fold resulting in a doubled concentration of C5a/PBL, whereas the corresponding concentration of C5a in plasma remained relatively constant. Postoperatively, the concentration of C5a associated with the PBL and in plasma fluctuated with the maximums being at 8 and 24 hours, respectively. In contrast to C5a in plasma, the concentration of cell-associated C5a correlated with number of PBL or polymorphonuclear leucocytes (PMN). The plasma concentration of IL-8 doubled during the operation, reached a six-fold maximum at 5 hours, and declined after 24 hours to twice the initial concentration. There were no correlations between plasma IL-8 and either number of PBL, plasma C5a, or PBL-associated C5a. No TNF alpha was detected in the plasma. CONCLUSION: Tissue trauma caused by uncomplicated excision of rectal cancer leads to leucocyte mobilisation peroperatively, probably partly by complement activation and subsequent generation and binding of the chemotaxin C5a to PBL. However, other chemotaxins may also play a role.

Aged↗
PubMed2000

Protective effect of beta-glucan against systemic Streptococcus pneumoniae infection in mice.

The antimicrobial effect of soluble beta-1,3-D-glucan from Sclerotinia sclerotiorum (SSG) was examined in mice experimentally infected intraperitoneally (i.p.) with Streptococcus pneumoniae serotypes 4 and 6B. SSG was administered i.p. either 3 days before challenge or 3-48 h after challenge. The number of bacteria in blood samples and the mouse survival rates were recorded. Pre-challenge SSG administration protected dose-dependently against both S. pneumoniae type 4 and 6B infections. SSG injected 24 h post-challenge had a curative effect against type 6B but not type 4 pneumococcal infection. The data demonstrate that SSG administered systemically protects against pneumococcal infection in mice.

Animals↗
PubMed2000

Mechanism for uptake of silica particles by monocytic U937 cells.

We examined the mechanism for uptake by monocytic cells of particles found in the atmosphere of some industrial work places. As a model system, irregular crystalline silica particles (SPs), sphere-like cryptocrystalline microsilica particles (MPs) and carbon particles (CPs) were exposed to pro-monocytic U937 cells. Plasma-treated SP and MP, but not CP, activated the alternative complement pathway, but bound little C3b. However, all particles adsorbed serum IgG, IgA and IgM unspecifically. Phenotyping of U937 cells for complement receptors (CRs) and Fcgamma receptors (FcgammaRs) showed that interferon gamma (INFgamma) increased expression of FcgammaRI, CR3 (CD11b/CD18) and CR4 (CD11c/CD18) and that phorbol-12-myristate-13-acetate (PMA) increased expression of CR4. Scanning electron microscopy (SEM) demonstrated higher phagocytosis of plasma-treated SP than native SP by both PMA- and INFgamma-stimulated, but not unstimulated, cells. MP and CP could not be distinguished from cellular structures. Inhibition experiments in SEM revealed uptake of heparin-plasma-treated SP via FcgammaRI on INFgamma-stimulated U937 cells, but could not exclude possible participation of CR3. The results indicate that plasma-treated SPs bind Ig and are internalized by differentiated monocytic cells via FcgammaRI, which is known to trigger cellular production of toxic oxygen species that may induce pulmonary inflammation in vivo.

Complement Activation↗
PubMed1998

Processing of C5a by human polymorphonuclear leukocytes.

Uptake of human C5a by neutrophils was monitored in vitro using both 125I-labeled and unlabeled C5a. The ligand was internalized by the cells in a dose-dependent manner and maximal binding/uptake was observed after 5 min of incubation. Neutrophils were incubated with labeled C5a and the cytosol and supernatant were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. C5a degradation products were primarily observed in the supernatant, whereas most of the protein remained intact in the cytosol even after 60 min of incubation. Cytosol from neutrophils incubated for 20 min with unlabeled C5a was examined by radioimmunoassay and found to contain antigenically intact C5a and retained the ability to induce a neutrophil (shape change) response. The functional activity of C5a recovered from the cytosol was inhibited by antibodies to either C5a or the C5a receptor (CD88). This data supports our hypothesis that although C5a is internalized it remains antigenically intact and functionally active inside the cell and is primarily degraded extracellularly.

Complement C5a↗
PubMed1998

Protective effect of beta-glucan against mycobacterium bovis, BCG infection in BALB/c mice.

Beta-1,3-glucan is a potent stimulator of macrophage functions and has a protective effect against a range of infections in rodent models. We examined whether the agent could also protect against the intracellular Mycobacterium bovis, bacillus Calmette-Guérin (BCG) infection in mice. BCG-susceptible BALB/c mice were injected intravenously (i.v.) with beta-glucan or vehicle 3 days before, or with beta-glucan 7 days after i.v. challenge with live BCG bacilli. The animals were killed 4 or 8 weeks later, their organs were homogenized and applied to object slides and stained with auramin for counting of bacilli, or seeded onto agar in Petri dishes. Mice treated with beta-glucan both pre- and postchallenge had significantly lower numbers of BCG bacilli and BCG colony-forming units in spleen homogenates compared with controls 4 weeks after challenge. A similar, but not statistically significant, tendency was observed in spleen homogenates from mice killed 8 weeks after challenge. In homogenates of liver and lungs there were similar findings, but less pronounced. There was a dose-dependent effect of beta-glucan injected before BCG challenge on the number of BCG bacilli found in spleen and liver homogenates. In addition, antibody cross-reactivity was demonstrated between M. tuberculosis cell wall and beta-glucan. The results suggest that beta-glucan has a protective effect against M. bovis, BCG infection in susceptible mice.

Animals↗
PubMed1998

Effect of filtration and storage of platelet concentrates on the production of the chemotaxins C5a, interleukin 8, tumor necrosis factor alpha, and leukotriene B4.

BACKGROUND: The production in platelet concentrates (PCs) of C3 activation products (C3bc), terminal complement complex (TCC), and chemotaxins C5a, interleukin (IL)-8, tumor necrosis factor alpha (TNFalpha), and leukotriene B4 (LTB4) and the proposed reduction in concentration of the chemotaxins by white cell reduction were examined. STUDY DESIGN AND METHODS: Samples were collected from supernatants of PCs produced by apheresis (apheresis PCs) or from buffy coats (BC PCs) immediately after the production, after white cell-reduction filtration on Day 1, and after 5-day storage, and examined by enzyme immunoassays. RESULTS: Complement was activated in all PCs during storage, and the concentration of activation products was not influenced by prestorage filtration. In prestorage white cell-reduced BC PCs, only C3bc levels increased. Levels of IL-8, TNFalpha, and LTB4 increased during storage of apheresis PCs, but not in filtered units, except for LTB4. In contrast, levels of IL-8 decreased after storage of filtered BC PCs. C5a correlated significantly with IL-8, which also correlated with TNFalpha and LTB4. CONCLUSION: Both C5a and TNFalpha generation in apheresis PCs seem to induce white cell IL-8 production, which mediates cellular LTB4 release. Prestorage white cell reduction is recommended for reducing chemotactic cytokine and leukotriene levels in all PCs. Production of BC PCs is recommended to achieve less complement activation, which is not affected by filtration.

Blood Platelets↗
PubMed1998

Involvement of antilipoarabinomannan antibodies in classical complement activation in tuberculosis.

We examined alternative and classical complement activation induced by whole bacilli of Mycobacterium bovis BCG and Mycobacterium tuberculosis products. After exposure to BCG, there were higher levels of the terminal complement complex in sera from Indian tuberculosis patients than in sera from healthy controls. The addition of BCG with or without EGTA to these sera indicated that approximately 70 to 85% of the total levels of the terminal complement complex was formed by classical activation. Sera from Indian tuberculosis patients contained more antibody to lipoarabinomannan (LAM) than sera from healthy Indians. Levels of anti-LAM immunoglobulin G2 (IgG2), but not anti-LAM IgM, correlated positively with classical activation induced by BCG in the sera. By flow cytometry, deposition of C3 and terminal complement complex on bacilli incubated with normal human serum was demonstrated. The anticomplement staining was significantly reduced in the presence of EGTA and EDTA. Flow cytometry also revealed the binding of complement to BCG incubated with rabbit anti-LAM and then with factor B-depleted serum. This indicates that classical activation plays a major role in complement activation induced by mycobacteria and that anti-LAM IgG on the bacilli can mediate this response. Classical complement activation may be important for the extent of phagocytosis of M. tuberculosis by mononuclear phagocytes, which may influence the course after infection.

Adolescent↗
PubMed1998

Chemotaxins C5a and fMLP induce release of calprotectin (leucocyte L1 protein) from polymorphonuclear cells in vitro.

AIMS: To determine whether the chemotaxins C5a and formyl peptide (fMLP) can stimulate the release of calprotectin, the major leucocyte protein of polymorphonuclear neutrophils (PMN). METHODS: A dose response curve for the uptake of 125I labelled rC5a and fMLP in PMN was determined by radioimmunoassay. The unlabelled chemotaxins were then incubated with PMN and the concentration of calprotectin in PMN lysates and supernatants was measured by an enzyme immunoassay. RESULTS: Both rC5a and fMLP induced release of calprotectin from PMN in a dose dependent manner as determined by a reduction in intracellular calprotectin concentration. A minimum of approximately 10% of total PMN calprotectin was retained at concentrations of 10-100 nM of rC5a and 0.1-10.0 nM of fMLP. Antibodies to C5a reduced the rC5a mediated release of calprotectin, and the fMLP antagonist N-t-Boc-MLP inhibited the fMLP induced calprotectin release. Because receptors for rC5a (CD88) and fMLP are G protein coupled and thought to be pertussis toxin sensitive, PMN were incubated with this toxin before the experiments. The toxin was found to reduce uptake of rC5a by the cells and to inhibit rC5a and fMLP mediated calprotectin release. CONCLUSIONS: rC5a and fMLP mediate release of calprotectin from PMN in vitro. This effect might be important during human infections in vivo.

Antigens, Surface↗
PubMed1998

Leucocyte filtration during cardiopulmonary bypass hardly changed leucocyte counts and did not influence myeloperoxidase, complement, cytokines or platelets.

In some patients, coronary artery bypass surgery induces postoperative organ dysfunction despite an apparently adequate revascularization and good haemodynamic performance. This complication may be caused by activation of the body's inflammatory systems on blood contact with large foreign surfaces in the extracorporeal circuit. Activated leucocytes may play an important role in organ damage, and it is conceivable that leucocyte removal by filtration may decrease the potential side-effects of cardiopulmonary bypass (CPB). The aim of the present study was to investigate possible effects of leucocyte filtration during the whole CPB period in elective coronary artery bypass surgery on biochemical and clinical parameters. Forty patients were randomized to extracorporeal circulation using a leucocyte-depleting filter (group L, n = 20) or to extracorporeal circulation with no leucocyte filter (group C, n = 20). In the leucocyte-depleted group, the mean total white blood cell counts increased from 6.3 (95% confidence interval, 5.5-7.0) x 10(9)/l to 7.0 (5.7-8.3) x 10(9)/l during extracorporeal circulation and in the control group from 6.3 (5.2-7.3) x 10(9)/l to 8.5 (7.2-9.8) x 10(9)/l. The intergroup difference was not statistically significant (p = 0.84). A substantial increase in concentrations of interleukin-6, myeloperoxidase and complement activation products were observed in both groups without statistically significant intergroup differences. It is concluded that the leucocyte-depletion filter did not cause a significant reduction of circulating white blood cells during CPB, and there were no significant differences between the groups with respect to the inflammatory markers studied.

Aged↗
PubMed1997

Both plasma- and leukocyte-associated C5a are essential for assessment of C5a generation in vivo.

BACKGROUND: Measurement of C5a in plasma is hampered by the rapid clearance of C5a as a result of cell binding. Therefore, an assessment of whether cell-bound C5a might better reflect C5a generation in vivo is essential. METHODS: We quantified plasma and leukocyte-bound C5a in samples from patients undergoing cardiopulmonary bypass, which is known to be associated with complement activation. C3 activation products and the terminal complement complex were measured as well. RESULTS: Plasma levels of C3 activation products and the terminal complement complex increased rapidly and significantly after the onset of cardiopulmonary bypass until they reached a plateau after 30 minutes. The concentration of plasma C5a increased steadily to twice baseline at the end of bypass. The concentration of leukocyte-associated C5a increased threefold after 10 minutes of cardiopulmonary bypass, when a plateau was reached. A positive correlation was found between levels of plasma C3 activation products or terminal complement complex and plasma C5a plus cell-associated C5a but not between C3 activation products or terminal complement complex and either one of the C5a variables. CONCLUSIONS: We conclude that both plasma C5a and leukocyte-associated C5a are needed for monitoring in vivo C5a generation.

Cardiopulmonary Bypass↗
PubMed1997

Cytotoxic effect of dibutyryl cAMP, phorbol-12-myristate-13-acetate and lipopolysaccharide, but not interferon-gamma, on promonocytic cell lines in vitro.

We studied whether inducers of cell differentiation alone could have cytotoxic effect on the promonocytic U937 and Mono Mac 6 cells in vitro. The cells were incubated with standard differentiating doses of interferon (IFN)-gamma, dibutyryl cAMP (Bt2cAMP) or the phorbol ester phorbol-12-myristate-13-acetate (PMA), with or without lipopolysaccharide (LPS), and both protein synthesis and viability were examined. In both U937 and Mono Mac 6 cells the incorporation of [3H]leucine was significantly reduced after PMA plus LPS stimulation, but not after IFN-gamma stimulation, when compared with controls. For U937 cells there was also reduced incorporation after Bt2cAMP stimulation. Trypan blue exclusion experiments and the number of cells remaining in the cultures indicated that Bt2cAMP-, PMA- and/or LPS-stimulated, but not IFN-gamma-stimulated, cells were less viable than unstimulated U937 or Mono Mac 6 cells. The results suggest that Bt2cAMP, PMA and LPS, but not IFN-gamma, are cytotoxic towards promonocytic cancer cell lines in vitro.

Bucladesine↗