Biomedical subjects
R Seljelid
Publications and source records attributed to R Seljelid.
The rediscovery of the macrophage.
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Semisoluble aminated glucan: long-term efficacy against an intraperitoneal E. coli challenge and its effect on formation of abdominal adhesions.
The first part of this study in the rat was designed to assess the immediate and, in particular, the long-term effects of semisoluble aminated glucan (SAG) with regard to an intraperitoneal (i.p.) E. coli challenge and side-effects. The severity of the E. coli peritonitis was evaluated by quantification of the concomitant bacteremia. The animals randomly received either 10 ml normal saline i.p. (controls) or 10 ml (50 mg) SAG i.p. (experimental groups). It was found that SAG had no immediate protective effect against the infectious challenge as no difference was detected in the bacterial clearance between saline- and SAG-treated rats at day 0. However, 2 days after injection of saline/SAG a substantial protection of SAG was noted as no blood-borne bacteria could be detected at 1, 2, 3, 4 and 5 h after the E. coli challenge in SAG-treated animals, whereas by contrast matching blood cultures were positive in all controls. A likewise protective effect against E. coli bacteremia of a single i.p. injection of SAG was demonstrated at 7, 21, and 49 days after the administration of the compound. During the 7-week experimental period no clinical side-effects of SAG were observed. At autopsy (days 0, 2, 7, 21, and 49, respectively) no gross pathologic conditions were found. Lung, spleen, and kidney sections from SAG-treated rats were normal, whereas tiny granulomas were exhibited in liver sections, possibly related to the hyperfunctional macrophage state which SAG induced. The second main object of the study was to evaluate SAG's effect on adhesion formation.(ABSTRACT TRUNCATED AT 250 WORDS)
Effector functions of macrophages.
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The protective effect of beta 1-3D-glucan-derivatized plastic beads against Escherichia coli infection in mice.
Pretreatment with beta-1,3-D-glucan-derivatized plastic beads conferred strong protection against Escherichia coli infection in mice. The protective effect showed a dose-response relationship to the amount of beads injected and was dependent on the time point of the injection relative to the infection with E. coli. A similar protection could be obtained in nude mice. Experiments with radioactively labelled bacteria as well as beads indicated a systemic effect of the beads. Macrophages extracted from animals treated with glucan plastic beads appeared highly stimulated. This was also true of cells that did not contain beads and presumably therefore not glucan, which seems to indicate a soluble stimulatory factor.
Production of prostaglandin E2 and interleukin 1 by mouse peritoneal macrophages stimulated with beta-1,3-D-glucan derivatized plastic beads.
Fluorescein-labelled plastic microbeads, with or without covalently attached beta-1,3-D-glucan, were injected into the peritoneal cavity of mice. Peritoneal cells were subsequently analysed by flow cytometry according to fluorescence and light scatter and separated into fluorescence positive and negative cells. We report that cells from animals treated with glucan-plastic beads produced large amounts of prostaglandin E2 (PGE2) whether the cells actually contained beads or not. On the other hand, cells from animals treated with glucan-plastic beads produced less thymocyte-stimulatory activity--presumably corresponding to interleukin 1 (IL-1)--than cells from control animals treated with commercial latex beads. However, when indomethacin was added, either in vivo or in vitro, cells from animals treated with glucan-plastic beads produced more thymocyte-stimulatory activity than controls. We interpret this to mean that glucan-plastic beads stimulate both IL-1 and PGE2, but that under circumstances where the cellular cyclo-oxygenase is not inhibited, the PGE2 will block IL-1 production.
Protection by aminated glucan in experimental endogenous peritonitis.
The effect of prophylactic intraperitoneal aminated glucan on the survival rate and formation of adhesions and abscesses was investigated in rats with acute and subacute peritonitis, respectively induced by cecal perforation and ileal ligation. A significantly reduced mortality was found in both forms of peritonitis. Pretreatment by aminated glucan also significantly reduced the number of abscesses and peritoneal adhesions. An about threefold increase in peritoneal macrophages in aminated glucan-treated rats compared to controls was noted. In vitro studies, using 32P-labelled Escherichia coli, demonstrated that peritoneal macrophages from aminated glucan-treated rats had an enhanced ability to engulf and degrade bacteria. Scanning electron microscopy showed that macrophages from aminated glucan-treated animals were highly spread with prominent ruffling and bacteria located intracellularly, as opposed to macrophages from controls which were rounded with bacteria on the cell surface.
The effect of splenectomy on Escherichia coli sepsis and its treatment with semisoluble aminated glucan.
Rats were subjected to sham laparotomy or splenectomy and were challenged with either 0.2 X 10(9) Escherichia coli intravenously or 1 X 10(9) E. coli intraperitoneally. By means of quantitative blood culturing asplenic animals were shown to have a significantly impaired ability to clear the bacteria in both forms of challenge. Treatment with intraperitoneally injected semisoluble aminated glucan (SAG), known to have strong macrophage-stimulatory properties, compensated completely for the asplenic state. The substance protected against postsplenectomy sepsis both when given before and when given after removal of the spleen. This protective effect of SAG seemed to last at least 3 weeks.
Treatment of experimental peritonitis in rats by transfer of peritoneal mononuclear cells from rats injected with semisoluble aminated glucan.
The efficacy of treatment with semisoluble aminated glucan (s.a.g.) and donor peritoneal mononuclear cells was investigated in two separate models of peritonitis (exogenous Escherichia coli challenge or caecal perforation). Intraperitoneal administration of s.a.g. significantly protected against both forms of peritonitis. Our previous studies indicated this protective effect to be mediated by macrophage activation, and this was corroborated by the effect of injecting rats with s.a.g.-stimulated donor peritoneal cells (approximately 95% macrophages) immediately after induction of peritonitis. Increased bacterial clearance and survival time were achieved with this treatment as compared with rats injected with cells from saline-treated donors. Scanning electron microscopy demonstrated activation of macrophages from the s.a.g.-treated rats. The results provided further support for the concept that s.a.g. exerts its therapeutic effect by stimulation of macrophages.
Hybrid resistance to the ascites form of the murine sarcoma.
An ascites form (AA) of the methylcholanthrene-induced murine sarcoma of C3H origin was used for present experiments. The AA cells were intraperitoneally injected to syngeneic (C3H, H-2k), allogeneic (DBA, H-2d) or semisyngeneic (C3H x DBA, H-2k/d) mice at a dose 10(7) cells per animal. The DBA mice developed small amount of ascites in the peritoneal cavity followed by rejection of allogeneic tumor cells and recovery. All syngeneic and semisyngeneic animals developed tumor and died. The C3H x DBA hybrids survived significantly longer than C3H mice (mean survival times: 21.9-24.8 and 10.1-11.8 days, respectively). The hybrid mice died with voluminous ascites tumor accompanied by a sponge-like form of tumor cell aggregates dispersed in the peritoneal cavity while the syngeneic mice died with small amount of dense ascites with an accompanying massive solid tumor in the vicinity of the spleen. Therefore in the experimental system used the semisyngeneic mice were found to develop a better response against parental-strain tumor cells than the syngeneic mice. This is an example of the phenomenon referred to as "hybrid resistance" or "allogeneic inhibition".
A water-soluble aminated beta 1-3D-glucan derivative causes regression of solid tumors in mice.
Meth A sarcoma, when inoculated in the skin, grew progressively in hybrid CB6 F1(Balb/c X C57B1/6) mice. When water-soluble aminated beta 1-3D-glucan (AG) was injected intravenously or intraperitoneally on day 7 of tumor growth, the tumors underwent complete regression. When the injection was performed on day 3 there was regression of tumors in only about half of the cases. When the injection was performed on day 14 there was no apparent effect on tumor growth. Tumors in thymectonized animals did not appear to respond to treatment with AG on day 7. The relatively simple chemistry and low toxicity of AG, together with its solubility in biological fluids, makes it a promising tool in experimental--and possibly clinical--tumor therapy.
In vitro interactions of murine peritoneal macrophages and sarcoma cells. I. Promotion of tumor cells proliferation by macrophages.
An ascites subline (AA) of the murine sarcoma MC1M grows in vivo in the peritoneal cavity but dies in vitro when cultured on glass or collagen. The viability of AA cells in vitro is not influenced in cocultures with fibroblast cell line L929, and is diminished in cocultures supplemented with macrophage culture supernatant or in cocultures with non-adherent peritoneal cells. However, AA cells proliferate in vitro on glass or collagen when cocultured with syngeneic, semisyngeneic, and allogeneic peritoneal macrophages. This was demonstrated by tritiated thymidine incorporation assay, by AA cell number counting, and by measuring AA cell protein content. Proliferation also occurs when AA cells are separated from the macrophage monolayer by millipore filters.
In vitro interactions of murine peritoneal macrophages and sarcoma cells. II. Induction of DNA synthesis in macrophages.
Unstimulated peritoneal macrophages grown in vitro for 5 days do not incorporate thymidine. Sarcoma (AA) cells introduced to the culture on the fifth day die and disintegrate whereas the macrophages become markedly stimulated and autoradiography shows that they are triggered to synthesize DNA. In syngeneic cocultures up to 28% of the macrophages incorporate thymidine after 5 days of coculture.
In vitro culture of frog peritoneal macrophages.
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Plasma fibronectin is sequestered into tissue damaged by inflammation and trauma.
Mechanical trauma or inflammatory reaction induced in striated muscle tissue of rats was followed by a flux of fibronectin from plasma into the damaged tissue, as determined by measurement of radioactivity, autoradiography and immunofluorescence. When homogenized muscle tissue was incubated with labelled fibronectin prior to separation of its subcellular components by ultracentrifugation, fibronectin bound to all fractions, but with strongest affinity for the microsomal and plasma membrane fraction. When trauma occurs, fibronectin from plasma binds to exposed structures on cell membranes and to components of connective tissue such as collagen and proteoglycans. Because of its ability to mediate cellular adhesion to tissue components, fibronectin probably exerts important functions in normal wound healing.
In vivo activation of mouse macrophages with beta-1,3-D-glucan-derivatized plastic beads.
Macrophages obtained from animals treated with beta-1,3-D-glucan-derivatized plastic beads were greatly stimulated, as judged by morphology, esterase release, and cytostatic effect on L-929 tumour cells in vitro. The pretreatment of mice with such beads conferred an apparent absolute local resistance to an otherwise lethal pneumococcal infection but had no effect on the growth of intraperitoneal AA ascites sarcoma. Moreover, peritoneal cells from animals pretreated with glucan beads did not protect the animals in a Winn assay.
Plasma fibronectin contributes to fibronectin in tissues.
Fibronectin is produced by several cell types, with hepatocytes currently recognized as the main source of plasma fibronectin. Mesenchymal cells produce fibronectin in vitro and probably do so even in vivo. But it is not clear if these cells represent the sole source of tissue fibronectin. In the present study, using direct and indirect immunofluorescence, fibronectin was found to occur ubiquitously in connective tissue in the rat. When 125I-labelled fibronectin was intravenously injected in rat, there was significant uptake of fibronectin in the tissues. The half-time for removal of labelled fibronectin in circulation was c. 15 hours. The authors conclude that flux of fibronectin occurs from plasma into the tissues and that in normal circumstances plasma fibronectin contributes to fibronectin in tissues.
Modulation of the morphology and glycosaminoglycan biosynthesis of human monocytes, induced by culture substrates.
Monocytes were isolated from human blood and cultured in vitro on plastic culture dishes or on fibronectin-coated dishes. After 5 days in vitro, the cells on plastic dishes displayed marked morphological changes compared with day 1, with an epithelioid appearance resembling that of foreign-body cells. This transition was inhibited in cells cultured on fibronectin-coated dishes. 35S-labelled polysaccharides were isolated from the culture media after 24h incubation periods with inorganic [35S]sulphate. The cells cultured for 5 days on a plastic substrate synthesized, and secreted into the medium, an oversulphated galactosaminoglycan previously shown to contain 4,6-di-O-sulphated N-acetylgalactosamine units [Kolset, Kjellén, Seljelid & Lindahl (1983) Biochem. J. 210, 661-667]. In contrast, 35S-labelled polysaccharide produced by cells cultured on plastic for 1 day only, or on fibronectin for either 1 or 5 days, contained only minor amounts of such disulphated sugar units. These findings indicate that the formation of oversulphated chondroitin sulphate is coupled to the conversion of monocytes into epithelioid cells. Furthermore, they suggest that the overall process is induced by contact with artificial substrates, and that it may be regarded as the equivalent of a foreign-body reaction in vivo.