Effects Of Bacterial Endotoxin Research Articles

The Effect of Stress on Host Defense System and on Lung Damage in Calves Experimentally Infected with Pasteurella Haemolytica Type A 1

This paper describes the influence of stress, immediately before a massive inoculation of a log-phase P. haemolytica A1 culture in brain-heart-infusion broth by fiberoptic bronchoscopy in 5 months old conventional calves. Differences in phagocytic cell function and numbers, lung function and lung tissue damage between stressed and non-stressed, infected calves were studied. Compared with the non-stressed calves before infection, the superoxide generation by blood polymorphonuclear leucocytes of the stressed animals was markedly reduced immediately after a 2 hours stress period, but it recovered within 3 days. The total numbers of phagocytic cells, harvested from lung lavage fluid 3 days after inoculation were twice as high in the non-stressed calves than in the stressed calves. In contrast, no differences in pulmonary lesions and functions were found between stressed or non-stressed calves. The role of several stress factors on infiltration and metabolic response of polymorphonuclear leucocytes in P. haemolytica infections and the effects of bacterial endotoxin and leukotoxin on alveolar and vascular injury are discussed.

Effects of bacterial endotoxin on ciliary activity in the tubotympanum.

The discovery of endotoxin in effusion of otitis media with effusion (OME) has suggested the possibility that bacterial endotoxin may be involved in the pathogenesis and development of OME. In this study, we investigated the direct effects of lipopolysaccharide (LPS), possessing the major part of endotoxin activity, on the ciliary activity in the tubotympanum. The study shows that LPS deteriorates ciliary activity in a dose-response fashion and that even low levels can, with extended exposure, cause dysfunction of cilia. It can be postulated that endotoxin in middle ear effusions aggravates the condition of mucociliary dysfunction thus leading to chronic OME.

Effect of bacterial endotoxin on lipoxygenase and cyclo-oxygenase metabolites by rat neutrophils and correlation with cellular functional parameters

The effect of Salmonella enteritidis endotoxin on in vitro rat neutrophil cyclo-oxygenase and lipoxygenase metabolism, phagocytic activity, superoxide (O2-) generation, and microbicidal activity was investigated. Incubation of polymorphonuclear leukocytes (PMN) with 5, 25, and 50 micrograms of endotoxin significantly enhanced synthesis of immunoreactive (i) leukotriene (LT)C4/D4 and thromboxane (Tx)B2 (P less than 0.001) as compared to control cells. Endotoxin 5 micrograms/ml produced optimal stimulation of the arachidonic acid metabolites. Calcium ionophore, A23187, significantly enhanced iLTC4/D4 and iTxB2 synthesis more than that elicited with endotoxin. Although phagocytic function was not significantly altered by endotoxin, intracellular killing of C. albicans demonstrated enhanced microbicidal activity at 5 micrograms/ml of endotoxin. Superoxide generation was significantly enhanced in neutrophils stimulated with phorbol myristate acetate (PMA). Endotoxin (5 micrograms/ml) further potentiated superoxide generation by these cells when stimulated by PMA. These findings demonstrate that endotoxin directly enhances neutrophil iLTC4/D4 and iTxB2 synthesis. The enhanced arachidonic acid metabolism elicited by endotoxin in these cells parallels increased microbicidal activity and superoxide generation.

Endotoxin, cerebral blood flow, amino acids and brain damage in young rabbits

The effects of bacterial endotoxin (lipopolysaccharide; LPS) on the cerebral blood flow (CBF), amino acid levels and brain histology were studied in young rabbits. The CBF was slightly decreased in the cerebral cortex and markedly decreased in the cerebral white matter at 60 and 120 min after LPS administration. Histological examination revealed only slightly pyknotic neurons around small vessels at 24 hours, and multifocal necrosis in the deep cerebral cortex and white matter at 72 hours. Some amino acids were increased in the plasma and brain regions at 24 hours after LPS administration, most of which were essential amino acids. GABA in the cerebral white matter was decreased at 24 hours. At 72 hours, most non-essential and glucogenic amino acids were decreased. These results suggest that the brain histological changes are related mainly to hypoperfusion and vascular damage in the brain. The amino acid changes may also be related to inappropriate amino acid metabolism associated with brain cell damage.

The Common Mediator of Shock, Cachexia, and Tumor Necrosis

Publisher Summary Complement-mediated injury, anaphylactic shock, and cell-mediated hypersensitivity reactions are often cited as disease processes in which the immune system has worked to the detriment of the host. Cachectin, acting alone and in concert with other mediators, is capable of evoking a “shock” state, in which hypotension, derangements of lipid and glucose metabolism, metabolic acidosis, and end-organ damage may injure or kill the host. When administered at low doses over a prolonged period, cachectin induces a state of anorexia and wasting similar to cachexia as it occurs in chronic infection or cancer. In part through its effects on vascular endothelial cells, cachectin can induce a coagulopathic state localized to certain vascular beds, leading to hemorrhagic necrosis of various tissues. This effect is particularly pronounced in certain tumor vessels, such that the hormone was originally recognized by its ability to provoke the hemorrhagic infarction of transplantable neoplasms, and was termed “tumor nec rosis factor.” On the one hand, as “cachectin,” the molecule was purified as a mediator of shock and wasting in chronic disease. On the other hand, as “tumor necrosis factor,” the molecule was isolated as a mediator of one of the “beneficial” effects of bacterial endotoxin, known as “induction of tumor necrosis.”

Effects of bacterial endotoxin on the ciliary activity in the in vitro eustachian tube.

We have used a tissue culture technique and a photoelectric method to examine the direct effect of lipopolysaccharide (LPS) on the ciliary activity present in the eustachian tube. Since LPS possesses the major part of the biological activity of endotoxin, our results show clearly that LPS deteriorates the ciliary activity in a dose-response fashion: LPS does not deteriorate the ciliary activity up to 168 h if its concentration is 1 ng/ml or less; 10 ng/ml LPS can cause deterioration of the ciliary activity with extended exposure (more than 96 h); LPS can cause dysfunction of the cilia rather quickly if the concentration is 100 ng/ml or more. Our results show that the ciliary activity in the eustachian tube under clinical conditions can be affected by endotoxin.

Effects of bacterial endotoxin on the ciliary activity in the in vitro middle ear mucosa.

In the present study, we have examined the hitherto unknown effects of long-term exposure to lipopolysaccharide (LPS), possessing the major parts of biological activity of endotoxin, on ciliary activity in the middle ear. Our results show that LPS can affect the ciliary activity in a dose-response fashion: 1) LPS does not impair the ciliary activity up to 168 h if the concentration is 1 ng/ml or less; 2) 10 ng/ml of LPS does not impair ciliary activity in the middle ear close to the tympanic orifice up to 168 h, but can cause reduced activity distal to the orifice after extended exposure (more than 96 h); 3) 100 ng/ml or more of LPS can cause dysfunction of cilia in the tympanic cavity, and in particular 1 microgram/ml or more of LPS can quickly disable the ciliary activity in the middle ear distal to the orifice.

Effects of bacterial endotoxin and platelet activating factor (PAF) on human platelet aggregation in native whole blood

The effect of bacterial endotoxins E. coll 0111:B4 or S. minnesota and platelet activating factor (1-O-alkyl-2-acetyl-SN-glycero-3-phosphorylcholine) on platelet aggregation in native whole blood (NWB) were evaluated by impedance aggregometry. In the absence of anticoagulants the patterns of impedance changes associated with aggregation were distinct from those of clotting. Both E. coll 0111:B4 and S. mlnnesota endotoxins shortened the time to clot formation, but impedance changes suggestive of accelerated platelet aggregation were minimal or absent. In contrast, PAF caused an increased impedance, with oscillations characteristic of aggregation, which in some instances was superseded by the smooth impedance change associated with clotting. E. coll 0111:B4 endotoxin blocked aggregation and delayed the onset of clotting after PAF, whereas S. minnesota endotoxln accelerated platelet aggregation by PAF in ten of thirteen experiments. Incubation of E. coll 0111:B4 endotoxin and PAF markedly enhanced aggregation by PAF, whereas the effect of S. minnesota was variable. Although E. coli 0111:B4 and S. minnesota endotoxins accelerated clotting but not platelet aggregation of human NWB In vitro , their Interaction with PAF is complex, depending on the type of endotoxin and individual reactivity. The findings suggest that endotoxin could interact with PAF to significantly augment possible hemorrhagic and/or thrombotic complications of septic shock In humans.

Effects of bacterial endotoxin on protecting copper-deficient rats from hyperoxia.

The administration of very low doses of bacterial endotoxin protects rats during exposure to hyperoxia and is associated with the induction of lung antioxidant enzyme activities. Copper-deficient rats have increased susceptibility to O2 toxicity, which may be related to their decreased lung superoxide dismutase activity (SOD) or decreased plasma ceruloplasmin concentrations. To determine whether endotoxin can protect against hyperoxia in this susceptible model, we exposed copper-deficient and control rats to a fractional inspiratory concentration of O2 greater than 0.95 for 96 h after pretreatment with 500 micrograms/kg of bacterial endotoxin or phosphate-buffered saline (PBS). Mortality in the copper-deficient and control rats given PBS and exposed to O2 for 96 h was 100%. Copper-deficient rats died significantly earlier during the exposure than controls. No mortality occurred in either group treated with endotoxin and hyperoxia despite the decreased activity of copper-dependent enzymes in the copper-deficient rats. Copper-deficient rats treated with endotoxin and exposed to hyperoxia did increase lung Cu-Zn-SOD activity, but activity remained below levels found in air-exposed controls. Mn-SOD activity was found to be induced above air-exposed controls in the copper-deficient rats treated with endotoxin and exposed to hyperoxia. Hyperoxic exposure resulted in a marked increase in plasma ceruloplasmin concentrations in the control rats, but no increases in ceruloplasmin occurred in the copper-deficient animals. Endotoxin protects copper-deficient rats from hyperoxia despite their decreased lung Cu-Zn-SOD activity, and decreased plasma ceruloplasmin.

Inhibition of ascorbic acid uptake by endotoxin: evidence of mediation by serum factor(s).

The effect of bacterial endotoxin on the ascorbic acid uptake by 3T6 fibroblasts was studied. Endotoxin inhibited ascorbic acid uptake by fibroblasts in a dose dependent manner. The inhibition by endotoxin takes place only in the presence of unheated serum; decomplementing serum by heat inactivation at 56 degrees C for 30 minutes eliminates endotoxin's inhibitory effect on ascorbic acid uptake. The effect of endotoxin appears to be instantaneous since the inhibition seen in the cells without any preexposure was similar to the cells preexposed to endotoxin for up to 6 hours. Polymyxin B sulfate which is known to bind the lipid A portion of endotoxin did not reverse the inhibition of ascorbic acid uptake caused by endotoxin.

Effects of bacterial endotoxins on neutrophil function.

The neutrophil is a key element in host resistance to bacterial infection. Bacterial products capable of subverting the antimicrobial properties of neutrophils can have a potentially deleterious effect on the host. Current knowledge of the effects of endotoxins derived from the outer cell envelope of gram-negative bacteria on neutrophil function is summarized. Available evidence indicates that endotoxins bind to neutrophils, both in vitro and in vivo. The lipid A region of the endotoxin macromolecule appears to be important in promoting the association of endotoxin with the neutrophil cell membrane. Endotoxin-neutrophil interactions can result in altered neutrophil adhesive and locomotory properties. Moreover, endotoxins have been demonstrated to induce selective degranulation of specific (secondary) granule constituents and to alter the oxidative and microbicidal properties of the neutrophil. Further studies are needed to define on a molecular level the nature of the endotoxin receptor, the precise structural components of endotoxin responsible for altering neutrophil behavior, and the transductional event(s) leading to neutrophil activation as a result of endotoxin exposure.

Effect of bacterial endotoxin on the transmembrane electrical potential and plasma membrane fluidity of human monocytes.

In order to gain insight into the physical interaction between bacterial endotoxins and the surface of human monocytes, we investigated the effects of Salmonella typhi endotoxin and lipid A on two functional properties of the plasma membrane of these cells: (1) the transmembrane electrical potential and (2) the fluidity of the lipid bilayer. Using the fluorescent lipophilic cationic probe 3,3'-dipropylthiodicarbocyanine (di-S-C3(5] to monitor the transmembrane electrical potential, we found that neither endotoxin nor lipid A induced depolarization of the monocyte's plasma membrane or impeded its ability to undergo depolarization in response to phorbol myristate acetate. When the resting transmembrane potential of the monocyte was analyzed by exposing di-S-C3(5)-labeled cells suspended in media containing incremental concentrations of potassium ion (K+) to valinomycin, no difference between the response of control cells and cells pretreated with endotoxin was noted. We next examined the effect of endotoxin and lipid A on the fluidity of the monocyte's plasma membrane by monitoring the intensity of the fluorescence of 1,6-diphenyl-1,3,5-hexatriene. By quantifying the intensity of parallel and perpendicular polarized light emitted by this membrane-embedded probe between 8 and 56 degrees C, measurements of molecular anisotropy were used to identify temperature-dependent phase transitions within the hydrocarbon region of the plasma membrane and to estimate the relative microviscosity of the lipid bilayer before and after exposing the cells to endotoxin or lipid A. Although the temperature at which phase transitions occurred was the same in all experimental groups of cells, preincubation of monocytes with either endotoxin or lipid A appeared to increase both the apparent microviscosity of the cell membrane and the order of the lipid bilayer as reflected by a decrease in its flow-activation energy. Our data indicate that when endotoxin molecules contact the surface of the monocyte, the lipid A moiety appears to become incorporated into the plasma membrane, increasing the microviscosity of the lipid bilayer without significantly altering its ionic permeability. We therefore conclude that the metabolic activation of monocytes by endotoxin is not coupled to, or initiated by, membrane depolarization.

Effects of bacterial endotoxins and their detoxified derivatives on serum and liver lipids in mice

The influence of different endotoxins (lipopolysaccharides, LPS) obtained from Serratia marcescens 08, Escherichia coli 089, and their derivatives, detoxified either by partial hydrolysis or irradiation, on serum and hepatic lipids and on serum lipase activity in C57Black mice was studied. Endotoxic LPS elevated the serum total lipids and lipoproteins, particularly the very-low-density lipoproteins, and induced a reversible accumulation of triglycerides in the liver. Since nontoxic preparations did not cause such alterations, it is assumed that the toxicity of LPS is an essential factor in causing lipid metabolism disorder. A nearly identical increase in the lipase activity was detected in 5 to 10 hr in the sera of experimental animals treated by both toxic and nontoxic preparations. Results indicated the potential advantage of using detoxified derivatives of bacterial endotoxins in human therapy.

Effect of bacterial endotoxin on gastric evacuation and passive absorption of salicylate in the small intestine

The salicylate content in blood plasma after its administration into the stomach and small intestine during experimental endotoxemia in mice has been measured. In early stages of intoxication gastric evacuation was fairly slow. Histamine increased, while its antagonist pyrilamine significantly reduced the observed disorder. In the last stages of intoxication, passive absorption in the small intestine increased. Administration of histamine, serotonin and ciproheptadine did not produce any essential effect on the salicylate transport across the intestinal wall.

The effect of bacterial endotoxin on synthesis of (Cu,Zn)superoxide dismutase in lungs of oxygen-exposed rats.

Administration of bacterial endotoxin to rats exposed to greater than 95% O2 results in increased lung superoxide dismutase activity, decreased O2-induced lung damage, and a 3- to 4-fold improvement in survival rate (Frank, L., Yam, J., and Roberts, R. J. (1978) J. Clin. Invest, 61, 269-275). Antibodies to rat liver (Cu,Zn) superoxide dismutase were prepared and utilized to investigate the mechanism by which endotoxin treatment leads to increased lung superoxide dismutase activity. Assay of enzyme activity and of immunodetectable enzyme showed that the increased activity is due to an increase in the number of enzyme molecules rather than activation of existing enzyme. Compared to air controls, lung slices from rats exposed to greater than 95% O2 and treated with endotoxin have elevated rats of synthesis of (Cu,Zn)superoxide dismutase (51%) and of total protein (100%). Lung slices from untreated rats exposed to greater than 95% O2 have no such elevations. Endotoxin treatment thus appears to stimulate lung protein synthesis, leading to greater (Cu,Zn)superoxide dismutase activity due to an increased number of enzyme molecules.

Effects of Bacterial Endotoxin on Pregnant Rats and Their Offspring

Effects of Bacterial Endotoxin on Pregnant Rats and Their Offspring

A study of the effects of bacterial endotoxin on periodontal tissue in vivo (author's transl)

A study of the effects of bacterial endotoxin on periodontal tissue in vivo (author's transl)

HEXACHLOROBENZENE-INDUCED STIMULATION OF THE HUMORAL IMMUNE RESPONSE IN RATS

Rats were fed diets containing 0, 500, 1000, and 2000 mg HCB/kg during a 3-week period. Marked weight increases of spleen, popliteal and mesenteric lymph nodes and of the liver were found. Histologically, the white pulp in the spleen was enlarged because of an increase in size of marginal zones and follicles. In addition, there was an increase of extramedullary hemopoiesis. In the lymph nodes, the number of high endothelial venules was increased at all dose levels. The number of neutrophils, basophils and monocytes in the peripheral blood was significantly increased, whereas peripheral lymphocyte counts were slightly higher. Total serum IgM levels were markedly increased, but IgG concentrations were unaltered. On the basis of this experiment, the 1000 mg HCB/kg diet level was chosen for the different function studies that were carried out after a 3-weeks dietary regimen. Regarding the humoral immunity, IgM antibodies to LPS were unaltered, whereas primary and secondary IgM and IgG antibody titers to tetanus toxoid were increased approximately three-fold. HCB did not significantly alter the cell-mediated immunity, as shown by the following parameters: resistance to Listeria monocytogenes infection, rejection of skin transplants, and delayed-type hypersensitivity to tuberculin. The phagocytizing capacity of macrophages was studied by measuring the blood clearance of carbon particles. HCB did slightly depress the phagocytic index, but the difference with control animals was statistically not significant. The in vitro responsiveness of thymus cells to the mitogens PHA, Con A, and PWM was not changed by in vivo HCB-treatment. On a cell-for-cell basis, the responsiveness of spleen cells was increased when cultured in the presence of LPS. On a whole organ basis, the response to PHA, Con A, PWM, and LPS was markedly enhanced because of an increase in the number of nucleated spleen cells. Regarding peripheral lymphocytes, only the response to the mitogen Con A was higher. On the basis of these studies it is concluded that HCB stimulates the humoral immune response in the rat, enhances the in vitro responsiveness of spleen cells to the different mitogens mainly as a result of an increase in the number of splenic lymphocytes, but does not alter the cell-mediated immunity as shown with in vivo tests. This result contrasts with data in the literature that show that HCB suppresses the humoral and cell-mediated immunity in mice. Finally, HCB pretreatment only marginally increased the susceptibility of rats to endotoxin, whereas mice have been shown to be 20-fold more susceptible to the lethal effects of bacterial endotoxin.

Attempts at analysis of toxicity of pertussis vaccine. III. Effects of endotoxin on leukocytosis in mice due to lymphocytosis-promoting factor and reference preparations for determination of lymphocytosis-promoting factor.

The effect of bacterial endotoxin on the change in peripheral leukocyte population in mice due to the lymphocytosis-promoting factor (LPF) was investigated. Endotoxin affected not only the total leukocyte count but also the leukocyte proportions at any observation time. Both the coefficient and the intercept of regression of the leukocytic response on dose of LPF were modified by endotoxin. Therefore, in a valid biological assay for LPF using the peripheral leukocyte count as a response, a common reference preparation available for any test materials, irrespective of presence or absence of endotoxin, will be impracticable. Two reference preparations were tentatively established, one being a vaccine and the other an LPF preparation containing little endotoxin. A unitage of LP activity was assigned to each reference preparation. The results also showed that an LPF material to be tested for its possible effects on the lymphatic tissues or the reticuloendothelial system should be free from endotoxin.

Encystation of axenically grownEntamoeba histolytica: Effect of bacterial endotoxins, starch and epinephrine

Axenically grown trophozoites of Entamoeba histolytica, starch fed and toxin treated, when incubated in a minimal medium containing epinephrine and theophylline at 33° ± 1°C were transformed to a round form with a thick outer wall; in contrast, the untreated cells died. These round bodies or “precysts” hatched to the trophic form when transferred to fresh growth medium. Formation of round bodies occurred even in the absence of cysteine but they were not mature and readily disintegrated.