Biomedical subjects

Geir Hetland

Publications and source records attributed to Geir Hetland.

7 recordsLinked to original sources

PubMed2006

An extract of the mushroom Agaricus blazei Murill protects against lethal septicemia in a mouse model of fecal peritonitis.

Bacterial septicemia is frequently occurring during gastroenterological surgery. Because of increasing problems in hospitals with bacteria developing multiresistance against antibiotics, prophylactic treatment using immunomodulators is interesting. We have examined the putatively anti-infective immunomodulatory action of the edible mushroom, Agaricus blazei Murill (AbM), in an experimental peritonitis model in BALB/c mice. The mice were orally given an extract of AbM or phosphate-buffered saline 1 day before the induction of peritonitis with various concentrations of feces from the mice. The state of septicemia, as measured by the number of colony-forming units of bacteria in blood, and the survival rate of the animals were compared between the groups. Mice that were orally treated with AbM extract before bacterial challenge showed significantly lower levels of septicemia and improved survival rates. Our findings suggest that the AbM extract, when given prophylactically, may improve health. Further studies are needed on humans when considering whether AbM could be used as an alternative treatment modality for patients at risk of contracting serious bacterial peritonitis.

Agaricus↗

PubMed2005

The fungal biopesticide Metarhizium anisopliae has an adjuvant effect on the allergic response to ovalbumin in mice.

The parasitic fungus, Metarhizium anisopliae, is non-pathogenic to humans and licensed for indoor control of cockroach infestation. An important reason for the elimination of this vermin is that sensitisation to cockroaches is associated with asthma. Previously M. anisopliae has been shown to cause allergic- and asthma-like responses in mice and in the present study we have examined the adjuvant activity of M. anisopliae on the allergic response to the model allergen ovalbumin (OVA) in a mouse model. Levels of OVA-specific IgE, IgG1 and IgG2a in serum were measured and the weight and cell number of the excised popliteal lymph node were determined. Mice primed with mycelium+OVA and boosted with OVA had increased anti-OVA IgE and IgG1 levels compared with mice primed with OVA alone or mycelium. Priming with M. anisopliae (as mycelium or MACA) increased weight or cell number of the excised PLNs. These results suggest that M. anisopliae has the ability to increase an allergic response to an allergen and consequently, may worsen allergy in susceptible individuals.

Adjuvants, Immunologic↗

PubMed2005

An extract of the medicinal mushroom Agaricus blazei Murill differentially stimulates production of pro-inflammatory cytokines in human monocytes and human vein endothelial cells in vitro.

An extract of the edible mushroom Agaricus blazei Murill (AbM) has known antitumor and anti-infection properties, probably mainly by stimulating mononuclear phagocytes of the native immune system. The aim of this work was to study the effect of AbM on the production by human monocytes and human umbilical vein endothelial cells (EC) of pro-inflammatory cytokines (IL-1beta, IL-6, IL-8, TNFalpha), the anti-inflammatory/T regulatory cytokine IL-10 and the pro-Th1 cytokine IL-12. AbM, in concentrations from 1-15%, induced a considerable and dose-dependent increase in production of IL-8, IL-6, TNFalpha and IL-1beta in monocyte cultures. The biosynthesis reached a plateau at a concentration of 10% of AbM, and was most pronounced for the three former cytokines. AbM did also dose-dependently stimulate EC production of IL-8,I L-6 and TNFalpha, but at lower levels compared with the monocytes. AbM did neither induce synthesis of cytokines IL-10 nor IL-12 in monocytes or EC. Our results demonstrate the differential effect of AbM stimulation on the magnitude of pro-inflammatory cytokines produced by monocytes and EC.

Agaricus↗

PubMed2004

Deoxynivalenol (DON) is toxic to human colonic, lung and monocytic cell lines, but does not increase the IgE response in a mouse model for allergy.

We examined whether the common crop mycotoxin deoxynivalenol (DON) from Fusarium species is toxic to human colonic (Caco-2), lung (A549) and monocytic (U937) cell lines. Moreover, since DON reportedly induces increased levels of Th2 cytokines and total IgE, and we have observed that mould extracts adjuvated allergy development in mice, possible adjuvant effect of DON on allergy was studied in a mouse model. For all the cells, exposure to DON for 24 h reduced cellular protein synthesis, proliferation and survival rate dose-dependently. In addition, production of IL-8 in the U937 cell line increased up to eight-fold at levels of DON just lower than the most toxic one, suggesting that IL-8 can be used as an additional index for cytotoxicity in mononuclear phagocytes. However, DON did not increase levels of allergen-specific IgE or IgG1 in the mouse model for allergy. These results suggest that DON, when inhaled or ingested, may have toxic effect on human alveolar macrophages and epithelial cells in lungs and colon, but does not increase the allergic response to allergens.

Adjuvants, Immunologic↗

PubMed2003

HUVEC take up opsonized zymosan particles and secrete cytokines IL-6 and IL-8 in vitro.

Uptake of zymosan A particles by human umbilical vein endothelial cells (HUVEC) and its effect on cellular cytokine and oxygen radical production was examined. HUVEC took up more serum-opsonized than -unopsonized zymosan as demonstrated by flow cytometry with fluorescence-labeled particles. The former uptake was inhibited in the presence of anti-C3c antibodies and thus complement-mediated. It probably occurred via CR1 (CD35), although participation of other receptors cannot be ruled out. Scanning electron microscopy indicated that HUVEC with fully internalized zymosan particles were damaged. Prolonged incubation of both serum-opsonized and -unopsonized zymosan particles with HUVEC induced increased secretion of the proinflammatory cytokines IL-6 and IL-8 to the cell culture supernatants, but had no effect on production of oxygen radicals. The results confirm previous reports that EC can internalize yeast and other pathogens and points to complement as a mechanism of uptake, but illustrates that the cells may be damaged in the process. Moreover, EC may participate in the anti-infection defense effort by secreting proinflammatory and chemotactic cytokines in response to the contact with pathogens.

CD11b Antigen↗

PubMed2002

beta-1,3-Glucan reduces growth of Mycobacterium tuberculosis in macrophage cultures.

The effect of beta-1,3-D-glucans SSG, from Sclerotinia sclerotiorum, or soluble (sMG) or particulate (pMG) MacroGard from baker's yeast on growth of Mycobacterium tuberculosis H37Rv in cultures of peritoneal macrophages from BALB/c mice was examined. After 24 h intracellular bacteria from lysed macrophages were cultured and the number of cfu counted. SSG given with challenge, but not 24 h after, reduced the number of M. tuberculosis cfu significantly. pMG, but not sMG, given with challenge had an even stronger inhibitory effect, which was enhanced after serum opsonization of the particles. The effect of serum-treated pMG was abrogated by addition of a monoclonal antibody to CD11b. The results indicate that beta-glucans inhibit growth of M. tuberculosis in host cells in vitro, probably due to cellular stimulation and/or competitive inhibition of uptake of bacteria via CR3 (CD11b/18).

Animals↗

PubMed2002

Human umbilical vein endothelial cells express complement receptor 1 (CD35) and complement receptor 4 (CD11c/CD18) in vitro.

We have examined complement receptors on human umbilical vein endothelial cells (HUVEC) and found that they express complement receptor 1 (CR1, CD35) and complement receptor 4 (CR4, CD11c/CD18), but not complement receptor 3 (CR3, CD11b/CD18). Binding of monoclonal antibodies against CR1 (CD35) and CR4 (CD11c/CD18) to HUVEC was demonstrated by flow cytometry. The presence of the corresponding mRNAs was confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR) and sequencing of the amplified cDNA fragments. When HUVEC were treated with inflammatory mediators, chemotactic agents or the secretagogue phorbol-12-myristate-13-acetate (PMA), no change in reactivity to CR1 (CD35) or CR4 (CD11c/CD18) monoclonal antibodies was detected on the surface of the cells compared with untreated cells. The presence of CR1 (CD35) and CR4 (CD1c/CD18) on HUVEC indicates that endothelial cells (EC) have the potential to bind C3b and iC3b, respectively, which both mediate biological effects in the course of complement activation.

Antibodies, Monoclonal↗