RELATIONSHIP BETWEEN PARTICLE SIZE AND BIOLOGICAL ACTIVITY OF E. COLI BOIVIN ENDOTOXIN

André Boivin: A pioneer in endotoxin research and an amazing visionary during the birth of molecular biology

André Boivin (1895–1949) started his career in Marseille as a biochemist. Soon after the discovery of insulin, he worked on its purification, allowing for the treatment of local patients. He later moved to Strasbourg and set-up a microtitration technique of small carbon molecules and a method for quantifying purine and pyrimidine bases. His main scientific contribution occurred in Bucharest, where he was recruited to organize the teaching of medicinal chemistry. Together with Ion and Lydia Mesrobeanu, at the Cantacuzene Institute, they were the first to characterize the biochemical nature of endotoxins, which he termed the “glucido-lipidic antigen.” After joining the Institut Pasteur annex near Paris, he worked with Gaston Ramon pursuing his research on smooth and rough LPS. Additionally, with Albert Delaunay, he researched the formation of exotoxins and antibodies (Abs). He was nominated assistant-director of the Institut Pasteur in 1940. He initiated research on bacterial DNA and RNA, and was the first to hypothesize on how RNA fits into gene function. In 1947 he moved for a second time to Strasbourg, accepting a position as a Professor of Biological Chemistry. After his premature death at the age of 54, the French academies mourned his loss and recognized him as one of their outstanding masters of biochemistry, microbiology, immunology, and molecular biology.

Effect on particle size of solubilization of wild-type and Re chemotype lipopolysaccharides solubilized with bovine serum albumin and triethylamine

Disaggregation of wild-type and Re chemotype lipopolysaccharides (LPS) has been accomplished by solubilization with triethylamine followed by stabilization with bovine serum albumin in order to determine the degree of aggregation. Solubilization with 1.5% triethylamine was found to be more effective than with lower concentrations, as judged by permeation chromatography. Chromatographic analysis of triethylamine-bovine serum albumin-disaggregated LPS showed a range of particle sizes. Wild-type LPS yielded size classes of 1 X 10(6) to 4 X 10(6) daltons, 250,000 daltons, and 20,000 daltons. Re LPS yielded size classes of 1 X 10(6) to 4 X 10(6) daltons and 20,000 daltons. Untreated LPS was always greater than 4 X 10(6) daltons. Chemical characterization of the size classes revealed 3-keto-2-deoxyoctonate in all size classes and suggests that the O-antigenic side chain length may determine the aggregate size in solubilized LPS.

Biological and physicochemical properties of the lipopolysaccharide of Chromatium vinosum

The lipopolysaccharide (LPS) of Chromatium vinosum has anticomplementary activity. This anticomplementary activity is destroyed by alkaline digestion of the LPS and is suppressed by both Mg2+ and Ca2+ ions. Treatment of the LPS with ethylenediaminetetraacetic acid, sodium deoxycholate, or dimethyl sulfoxide did not affect its toxicity toward mice; however, alkaline-treated LPS was not toxic. Treatment of the LPS with sodium deoxycholate, dimethyl sulfoxide, or sodium dodecyl sulfate resulted in reversible dissociation into subunits. Aggregation of the subunits into the original form was achieved by removing the dispersing agent by dialysis against distilled water followed by freezing and thawing. Electron micrographs of phenol-extracted LPS showed long filaments. Electron micrographs of sodium deoxycholate- and sodium dodecyl sulfate-treated and dialyzed LPS showed a mixture of small subunits and short filaments, whereas dimethyl sulfoxide-treated and dialyzed LPS contained only small ovoid spheres. The LPS produced an ordered series of multiple bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A similar banding pattern was observed for Salmonella abortus-equi and Proteus mirabilis LPS. The C. vinosum LPS appears to be mitogenic for mouse spleen cells.

Purification and properties of Klebsiella pneumoniae heat-stable enterotoxin

The enterotoxic material in cell-free growth preparations of Klebsiella pneumoniae serotype 5 was purified by sequential ultrafiltration and gel filtration (GF) procedures and the fractions were assayed for enterotoxic activity by determining their ability to induce in vivo net water secretion in the rat jejunum. Whole-cell lysates were inactive. Anaerobic broth culture conditions yielded a 10-fold increase in toxin production over aerobic conditions. Enterotoxic activity was absent in the UM-10 retentate of the broth filtrate but present in both the retentate and filtrate of the UM-2 membrane. GF of the two UM-2 ultrafiltration fractions through a Sephadex G-25 column yielded an active eluate, whose potency was increased by 10- or 200-fold, in or adjacent to the void volume. When subsequently passed through a G-50 column, these pools eluted at a Kav of between 0.4 and 0.6 and were further increased in potency by two- or fivefold. A second equally potent fraction was also recovered in the void volume of the G-50 eluate of the UM-2 filtrate; this may represent a polymer. Progressive purification by GF was associated with an increased protein and decreased carbohydrate content of the most active fractions. The most active G-50 eluate of the UM-2 retentate had a minimal effective enterotoxic dose of 5 mug/ml and that of the filtrate was less than 0.1 mug/ml. Heating the active GF eluates to 100 C for 30 min did not abolish enterotoxic activity and lowering the pH to 1 or incubation with either Pronase or trypsin had no effect on activity. These observations indicate that K. pneumoniae heat-stable enterotoxin is probably a single toxin with an apparent molecular weight in the range of 5,000. The elution characteristics during GF as well as the chemical composition of the most purified enterotoxin fractions indicate that the toxin is not associated with endotoxin.

Disaggregation of endotoxin by isolated rat liver plasma membranes and lack of product binding

The interaction of bacterial endotoxin with isolated rat liver cell membranes was studied to determine the extent and nature of any binding. Serratia marcescens endotoxin was incubated with isolated rat liver plasma membranes for varying periods of time at 37 C, and this mixture was then centrifuged through a discontinous sucrose density gradient. The membranes banded primarily at the 35 to 45% sucrose interface, whether or not they had been incubated with endotoxin. The endotoxin distributed itself throughout the gradient except when incubated with membranes, in which case it failed to sediment. This membrane-induced alteration in sedimentation could be prevented by heat inactivation of the membranes, and was found to be pH, time, temperature, and concentration dependent. There was neither associated degradation of the endotoxin, as measured by molecular sieve chromatography, nor loss in toxicity, as determined in lead-sensitized rats. These observations are consistent with an enzymatic disaggregation of the endotoxin by membranes and could represent a step in the uptake of the endotoxin by the reticuloendothelial system. No significant binding of this disaggregated endotoxin to the membranes could be detected, either after gradient separation or after repeated washing. This finding strongly suggests that, at least in cells that are active in the uptake of endotoxin, membrane-endotoxin interactions may be relatively transitory in nature, and that firm adherence to such membranes may not be a central feature of endotoxin toxicity.

Immunization against retrograde pyelonephritis. I. Production of an experimental model of severe ascending Escherichia coli pyelonephritis without bacteremia in rats

Retrograde pyelonephritis was produced in rats by introducing into the bladder a small refluxing inoculum of Escherichia coli that would enter the renal pelvis but not the blood stream. At the same time the left ureter was partially obstructed for 18 hours. This model differs from previous attempts to produce E coli pyelonephritis with large (0.6 ml) volumes infused into the bladder, because such large volumes cause bacteremia and hematogeneous pyelonephritis. Since retrograde E coli pyelonephritis in patients is not accompanied by positive blood cultures, the model described in this report is believed to accurately mimic human pyelonephritis and to allow a realistic approach to the study of immunity against retrograde infection in the urinary tract.

Membranous structure of purified Escherichia coli lipopolysaccharide

The ultrastructure of the purified and lyophilized endotoxin from Escherichia coli O111 was observed by ultrathin sectioning. Onion-like globular membrane structures were observed in addition to rod-like and ribbon-like structures, indicating the existence of a globular membrane structure even in the dried state.

Characteristics of Endotoxin-Altering Fractions Derived from Normal Serum III. Isolation and Properties of Horse Serum α 2 -Macroglobulin

The endotoxin-altering activity of fractions isolated from normal horse serum was examined by incubation of Salmonella typhosa strain 0-901 endotoxin (Boivin) in a solution of the fraction, and subsequent quantitation of any diminution in the capacity of endotoxin to be precipitated by specific anti-endotoxin antiserum. The horse serum fraction isolated by precipitation with ammonium sulfate at a concentration between 1.6 and 2.7 m was incubated with Pronase PA and then with trypsin. When this partly digested fraction was passed twice through a Sephadex G-200 column and eluted with 0.2 m tris(hydroxymethyl)aminomethane buffer, most of the endotoxinaltering activity was found in the first protein peak designated F-1a. F-1a was found to be homogeneous and corresponded to an α 2 -macroglobulin by the techniques of electrophoresis, immunodiffusion, and ultracentrifugation. Approximately 100-fold more F-1a than endotoxin was needed to reduce the antigenicity of the endotoxin by one-half. Alteration was increased when F-1a was incubated with the endotoxin at acid p H or at 45 C rather than at 37 C and was lost after heating F-1a at 56 C for 30 min. N -ethylmaleimide increased the endotoxin-altering activity of horse serum, F-1a, and human plasma fraction III 0 , whereas p -chloromercuribenzoate did not. On the other hand, diazonium-1-H-tetrazole, iodoacetic acid, and benzylchloride suppressed the activity of F-1a. When the interaction of endotoxin and F-1a was examined by immunodiffusion techniques, depolymerization of the endotoxin molecule was indicated. The endotoxin-altering factor of horse serum is discussed in relation to the mechanisms of other known reagents, such as deoxycholate and sodium lauryl sulfate.

Surface antigens of smooth brucellae

Surface antigens of smooth brucellae were extracted by ether-water, phenol-water, trichloroacetic acid, and saline and examined by immunoelectrophoresis and gel diffusion with antisera from infected and immunized rabbits. Ether-water extracts of Brucella melitensis contained a lipopolysaccharide protein component, which was specific for the surface of smooth brucellae and was correlated with the M agglutinogen of Wilson and Miles, a polysaccharide protein component devoid of lipid which was not restricted to the surface of smooth brucellae and was not correlated with the smooth agglutinogen (component 1), and several protein components which were associated with internal antigens of rough and smooth brucellae. Immunoelectrophoretic analysis of ether-water extracts of B. abortus revealed only two components, a lipopolysaccharide protein component, which was correlated with the A agglutinogen, and component 1. Component 1 from B. melitensis and B. abortus showed identity in gel diffusion tests, whereas component M from B. melitensis and component A from B. abortus showed partial identity with unabsorbed antisera and no cross-reactions with monospecific sera. Attempts to prepare monospecific sera directly by immunization of rabbits with cell walls or ether-water extracts were unsuccessful. Absorption of antisera with heavy fraction of ether-water extracts did not always result in monospecific sera. It was concluded (as has been described before) that the A and M antigens are present on a single antigenic complex, in different proportions depending upon the species and biotype, and that this component is a lipopolysaccharide protein complex of high molecular weight that diffuses poorly through agar gel. Components 1, A, and M were also demonstrated in trichloroacetic acid and phenol-water extracts. With all extracts, B. melitensis antigen showed greater diffusibility in agar than B. abortus antigens. After mild acid hydrolysis, B. abortus ether-water extract was able to diffuse more readily.

Identification of the toxic component of Brucella abortus endotoxin and its labeling with radioactive chromate

The evidence obtained from immuno-gel diffusion, centrifugation, and toxicity studies employing the serum iron assay proved that most of the toxicity in an ether-water brucella endotoxin preparation lies in the slow-diffusing component identified as the biologically active endotoxin. Subsequent destruction of the slow-diffusing component by acid hydrolysis resulted in a corresponding loss of toxicity. Chromate-51 was found to attach almost entirely on the slow-diffusing biologically active component and, hence, is a valid label for endotoxin derived from smooth Brucella abortus by the ether-water method.

Reaction of endotoxin and surfactants. I. Physical and biological properties of endotoxin treated with sodium deoxycholate

Ribi, E. (Rocky Mountain Laboratory, Hamilton, Mont.), R. L. Anacker, R. Brown, W. T. Haskins, B. Malmgren, K. C. Milner, and J. A. Rudbach. Reaction of endotoxin and surfactants. I. Physical and biological properties of endotoxin treated with sodium desoxycholate. J. Bacteriol. 92:1493-1509. 1966.-Endotoxins from three species of gram-negative bacteria were shown to be dissociated by the bile salt sodium deoxycholate (NaD) into nontoxic subunits with molecular weights of about 20,000. When the bile salt was removed by dialysis, the subunits reaggregated in an orderly manner to form a relatively uniform population of biologically active endotoxin particles with average molecular weights of 500,000 to 1,000,000. If a small amount of human plasma was added to the dissociated endotoxin before removal of the NaD, reassociation apparently did not occur and the preparation remained nonpyrogenic. However, the plasma protein could subsequently be removed from the endotoxin subunits, and reaggregation to the toxic form would then occur. The studies on the physical nature of endotoxin performed with biophysical solution techniques were supplemented and confirmed by direct examination of the endotoxin polymers by electron microscopy. The results of these studies were consonant with the theory that the biologically active endotoxic elements are composed of micellar aggregates of linear lipopolysaccharide subunits.

Immunochemistry of O and R antigens of Salmonella and related Enterobacteriaceae

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