Effects Of Bacterial Endotoxin Research Articles

Effects of Bacterial Endotoxin (LPS) on Cardiac and Synaptic Function in Various Animal Models: Larval Drosophila, Crayfish, Crab and Rodent

Effects of Bacterial Endotoxin (LPS) on Cardiac and Synaptic Function in Various Animal Models: Larval Drosophila, Crayfish, Crab and Rodent

Effects of bacterial endotoxin on regulation of the heart, a sensory-CNS-motor nerve circuit and neuromuscular junctions: Crustacean model

Eatable crustaceans are susceptible to bacterial septicemia from injury or a compromised immune defense, which can possibly have detrimental effects in mammals that consume them. Since many crustaceans (i.e., crabs, lobsters and crayfish) are used for animal food and human consumption, it is of interest to understand the effects potential bacterial infections can have on their health as well as ours, including effects on cardiovascular and neuromuscular activities. The Red Swamp crayfish (Procambarus clarkii) was used as a model crustacean to investigate the effect of direct exposure to isolated endotoxin lipopolysaccharide (LPS) and the associated peptidoglycans from gram-negative bacteria (Serratia marcescens). S. marcescens is a common strain identified to cause septicemia in mammals and is prevalently found in nature. LPS injection into the hemolymph of crayfish revealed acute changes in heart rate and effects on survival. Direct LPS exposure on an in situ sensory-CNS-motor circuit produces a decrease in recruiting of the motor nerve at 500 μg/ml but has no significant effect at 100 μg/ml. At the isolated neuromuscular junction, the direct action of the LPS endotoxin (500 μg/ml) enhances evoked synaptic transmission, while not altering facilitation. Also, the amplitude and the frequency of spontaneous vesicle fusion events was not altered by LPS exposure. However, the resting membrane potential of the muscle transiently hyperpolarizes. These direct actions on tissues appear to be independent of innate immune responses and suggest the LPS targets on these tissues have a role in excitability of cellular function. {242 words}.

The Effects of Bacterial Endotoxin (LPS) on Cardiac and Neural Function in Various Animal Models

The endotoxic effect from gram negative bacteria is primarily due to the lipopolysaccharides (LPS). LPS activates the innate immune response through a Toll‐like receptor 4 (TLR4) known as the CD14/TLR4/MD2 receptor complex in mammals. The Toll receptors are conserved from primates to insects. However, in insects the peptidoglycan recognition proteins (PGRPs) are the receptors which respond to LPS from gram negative bacteria. These PGRPs activate the Immune Deficient (IMD) signaling cascade. There is a family of these receptors known in Drosophila melanogaster but their expression profiles in different tissues has yet to be fully elucidated. We examined a variety of model preparations to better understand the acute actions of exposure to LPS of Serratia marcescens to better understand the varied mechanisms of action. There is a differential, dose dependent effect of LPS in increasing and decreasing HR heart rate (HR) in the larval medicinal blow fly (Phaenicia sericata) and a fruit fly (Drosophila melanogaster). LPS depressed evoked and miniature (quantal) EJPs while hyperpolarizing the skeletal muscle in larval Drosophila, but increased EJPs with no effect on muscle membrane potential at the crayfish NMJ. Both NMJs are glutamatergic. LPS had no effect on sensory transduction of proprioceptive sensory neurons in crayfish and blue crab. LPS at the cholinergic frog NMJ depressed synaptic transmission with no effect on muscle membrane potential. LPS depressed sensory‐CNS‐motor nerve circuits in both crayfish and larval Drosophila. Synaptically‐evoked population spikes in field CA1 of the mouse hippocampus were also significantly reduced by acute LPS applications. The varied effects of LPS in different model systems paves the way to examining differential cellular mechanisms induced by acute exposure to LPS.Support or Funding InformationDept of Biology, Univ. of KY laboratory funds and personal funds (RLC)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Differential Effects of Sepsis and Chronic Inflammation on Diaphragm Muscle Fiber Type, Thyroid Hormone Metabolism, and Mitochondrial Function.

The diaphragm is the main respiratory muscle, and its function is compromised during severe illness. Altered local thyroid hormone (TH) metabolism may be a determinant of impaired muscle function during illness. This study investigates the effects of bacterial sepsis and chronic inflammation on muscle fiber type, local TH metabolism, and mitochondrial function in the diaphragm. Two mouse models were used: sepsis induced by S. pneumoniae infection or chronic inflammation induced by subcutaneous turpentine injection. In vitro, the effect of bacterial endotoxin (LPS) on mitochondrial function in C2C12 myotubes was studied. Sepsis induced a transient increase in the fiber type I profile and increased Dio3 expression while decreasing Dio2, Thra1, and Slc16a2 expression. Triiodothyronine positively regulated genes Tnni2 and Myog were decreased, indicating reduced TH signaling in the diaphragm. In contrast, chronic inflammation increased the fiber type II profile in the diaphragm as well as Thra1, Thrb1, and Myog expression while decreasing Dio3 expression, suggesting increased TH responsiveness during chronic inflammation. LPS-stimulated C2C12 myotubes showed decreased Dio2 expression and reduced basal oxygen consumption as well as non-mitochondrial respiration. The same respiratory profile was induced by Dio2 knockdown in myotubes. The in vivo results show differential effects of sepsis and chronic inflammation on diaphragm muscle fiber type, TH metabolism, and mitochondrial function, while the in vitro results point to a causal role for altered TH metabolism in functional muscle impairment. These findings may be relevant for the pathogenesis of impaired respiratory function in critical illness.

Effects of Bacterial Endotoxins on the Toxicity of Extracellular Histones to Mammalian Cells

During Bacterial infections, endotoxins are released from the bacterial cell wall and histones from damaged host cells into the extracellular milieu. Extracellular histones are known to act as potent bactericides against a wide range of pathogens. Additionally, deleterious effects of histones on mammalian cells were recently reported. Unpublished data from our lab show that the bactericidal effects of histones can be blocked by the presence of bacterial lipopolysaccharide (LPS). However, the effects of LPS on histone toxicity to the viability of mammalian cells are unknown. Using macrophage‐like RAW 264.7 cells, we studied the effects of extracellular histone in the presence of LPS on host macrophages. We used Trypan blue exclusion and MTT assays as indicators of cell viability. In accordance to previous studies, a substantial decrease in cell viability was found in cells treated for 24 h with histone alone. However, simultaneous treatment with LPS significantly blocked histone‐induced cell death. These results demonstrate that co‐treatment of extracellular histone with bacterial endotoxin decreases its detrimental effects on cell viability; suggesting, bacterial products may interfere with histone‐mediated cell death. We are currently investigating potential mechanisms underlying these observations. These studies give new insights on host‐pathogen interactions during infections.

Results of Using Selective Endotoxin Adsorption in Cancer Patients with Sepsis

Objective: to study the clinical efficiency of using selective lipopolysaccharide (LPS) adsorption in postoperative gram negative sepsis in cancer patients. Subjects and methods . Examinations were made in 47 patients (11 women and 36 men) aged 47 to 84 years, who had been operated on for cancer and whose postoperative period had been complicated by gramnegative sepsis. The patients were divided into 2 groups: 1) 15 patents who received standard therapy (a control group); 2) 32 who had LPS adsorption using immobilized polymyxin B (a study group). Results. Upon completion of the selective LPS adsorption program, there was regression of the clinical signs of sepsis, statistically significantly lower peripheral blood leukocyte and neutrophil levels, and better blood biochemical parameters in 87.5% of cases. High baseline endotox in activity decreased from >0.6 to <0.4 units in 89% of the patients. After the final session of LPS adsorption, the need for vasopressor support reduced due to hemodynamic profile optimization. After selective endotoxin adsorption cycles, 15 of 26 cases did not need to continue organ replacement therapy. Twentyeightday mortality rates in the study and control groups were 25.0 and 53.3%, respectively. Conclusion. Incorporation of LPS adsorption into a set of intensive therapy for gramnegative sepsis is pathogenetically substantiated and can effectively abolish the manifestations of the systemic effects of bacterial endotoxin. The early and timely use of LPS adsorption provides inhibition of an initiating stimulus, which makes it possible to prevent the progression of a septic process and the development of severe sepsis and septic shock and improves the results of therapy in cancer inpatients.

Effect of bacterial endotoxin on migration of gonadotropin-releasing hormone-producing neurons in rat embryogenesis

The effect of bacterial lipopolysaccharide endotoxin (LPS), immune system activator, on differentiation and migration of gonadotropin-releasing, hormone producing neurons in rat embryogenesis has been studied. Intraperitoneal introduction of LPS (18 jg/kg) to pregnant rats on the 12th day of pregnancy led to 50% decrease in total number of GRH-neurons in the forebrain of 17-day-old embryos and 17% decrease in 19-day-old embryos. At the same time, the number of GRH-neurons in the nasal area of the head of 17- and 19-day-old embryos increased by 40 and 50%, respectively, whereas it increased by 20% in olfactory bulbs of 17-day-old embryos and did not changed in olfactory bulbs of 19-day-old embryos. Neither the total number of neurons nor their distribution patterns were affected by the introduction of LPS into pregnant rats on the 15th day of pregnancy. Singular localization of GRH-neurons in embryo forebrain was observed after LPS administration, whereas the neurons were located by groups of 3-4 cells in rostral areas. Therefore, at the early stages of pregnancy, LPS was shown to suppress initial stages of differentiation and migration of GRH producing neurons. The effects observed in our study may be mediated by LPS-induced, proinflammatory cytokines.

Effects of Bacterial Endotoxin on α-Synuclein Expression in the Lymph Node Leukocytes of Rats

The effects of bacterial LPS on the expression of early apoptosis marker (annexin V) and immunoreactive α-synuclein in mononuclear leukocytes of the mesenteric lymph nodes of rats were studied in vivo and in vitro. Injection of LPS increased the number of lymphocytes with high expression of immunoreactive α-synuclein in cell nucleus and cytoplasm (by 68.6±8.1%) and stimulated apoptosis in this population (by 96.0±3.6% of the control). The expression of α-synuclein in macrophages increased only in the cytoplasm and this increase was not paralleled by stimulation of apoptosis in these cells. The data indicate that LPS-induced elevation of α-synuclein in lymphocytes is a component of the mechanism of programmed death in these cells. The increase of α-synuclein expression in macrophages can be related to processes associated with their stimulation.

Escherichia coli contamination of menstrual blood and effect of bacterial endotoxin on endometriosis

To test the hypothesis that bacterial contamination of menstrual blood could be a local biologic event in the development of endometriosis, menstrual blood was cultured and bacterial endotoxin was measured in menstrual blood and peritoneal fluid. Our results suggest that compared with control women, higher colony formation of Escherichia coli in menstrual blood and endotoxin levels in menstrual fluid and peritoneal fluid in women with endometriosis may promote Toll-like receptor 4-mediated growth of endometriosis.

In vitro effects of lactoferrin on intestinal and mammary epithelial cell lines

Lactoferrin is an iron binding glycoprotein endowed with multiple functions, including non-specific immune defence against pathogens, immunomodulatory activity and regulation of cell growth. The gastrointestinal tract of the newborn and the mammary gland are targets of the biological action of lactoferrin. This work aimed at examining the effects of human and bovine lactoferrin on cell growth using intestinal and mammary epithelial cell lines and at evaluating the protective effect of bovine lactoferrin against cytotoxic damage induced by bacterial lipopolysaccharides in a bovine mammary epithelial cell line. It was shown that lactoferrin could be involved in regulating the growth of both intestinal and mammary epithelial cells depending on its concentrations, cell culture conditions and cell line used. The presence of lactoferrin binding sites on the cell surface was also discussed. Moreover, the data obtained suggested that bovine lactoferrin could contribute to counteract the effect of bacterial endotoxins.

Mesenchymal precursor cells modulate the effect of bacterial endotoxin on inflammatory gene expression in human cells of monocyte lineage

Mesenchymal precursor cells modulate the effect of bacterial endotoxin on inflammatory gene expression in human cells of monocyte lineage

Effect of Bacterial Endotoxins on Superovulated Mouse Embryos In Vivo: Is CSF-1 Involved in Endotoxin-Induced Pregnancy Loss?

Mammalian embryonic development is regulated by several cytokines and growth factors from embryonic or maternal origins. Since CSF-1 plays important role in embryonic development and implantation, we investigated its role in gram-negative bacterial LPS-induced implantation failure. The effect of LPS on normal (nonsuperovulated) and superovulated in vivo-produced embryos was assessed by signs of morphological degeneration. A significantly similar number of morphologically degenerated embryos recovered from both nonsuperovulated and superovulated LPS treated animals on day 2.5 of pregnancy onwards were morphologically and developmentally abnormal as compared to their respective controls (P < .001. Normal CSF-1 expression level and pattern were also altered through the preimplantation period in the mouse embryos and uterine horns after LPS treatment. This deviation from the normal pattern and level of CSF-1 expression in the preimplantation embryos and uterine tissues suggest a role for CSF-1 in LPS-induced implantation failure.

The effects of bacterial endotoxin on cochlear function and the blood labyrinth barrier

Problem: Middle ear infection, one of the most common childhood diseases, has the potential to cause inner ear pathology, resulting in hearing loss or communication disorders. Specific mechanisms responsible for inner ear dysfunction due to otitis media are not clearly understood. It appears that inflammatory mediators and bacterial toxins pass through the round window membrane resulting in structural and biochemical changes in the inner ear leading to auditory dysfunction. This study was undertaken to examine auditory function and the blood labyrinthine barrier in the lateral wall of the cochlea, after bacterial endotoxin administration. Methods: Chinchillas weighing 400 to 500 g were injected intravenously with 1 ml of 10 mg/ml LPS (LPS, Sigma Co, derived from Escherichia coli serotype 055:B5). The same volume of normal saline was administered intravenously as control. Hearing threshold was measured by auditory brainstem response (ABR) before and after injection. Two hours after injection, 3.0 mL of 2% Evan’s blue was injected via the femoral vein and 3 hours later, the animals were euthanized by intracardiac perfusion of fixative. Temporal bones were removed and sections were coated to retain fluorescence of Evan’s blue. Fluorescence of Evan’s blue was detected by fluorescence microscopy and quantitative analysis of Evan’s blue extravasation in the lateral wall was measured by spectrophotometry. Results: There was leakage of Evan’s blue from vessels in the lateral wall after LPS administration and the hearing threshold change was 10–15 dB lower than controls. Conclusion: Administration of bacterial endotoxin caused a threshold change of ABR and breakdown of the blood labyrinthine barrier of the lateral wall, as evidenced by leakage of Evan’s blue. Extravasation of substances may interfere with ion transport, especially potassium, through the lateral wall and cause disturbance of the auditory transduction process leading to hearing dysfunction. Significance: The results of this study partially clarify mechanisms involved in inner ear disturbances caused by middle ear infection. Support: None reported.

Is there a functional role of bacterial endotoxin receptor (Tlr4) in pituitary tumor progression?

Members of the Toll receptor (Tlr) family are critically involved in the innate immune response after bacterial infections. Effects of bacterial endotoxins (LPS) of gram-negative bacteria are mediated predominantly by Tlr 4. We have shown that LPS stimulated IL-6 secretion in pituitary folliculostellate (FS) cells via Tlr4 receptors and the p38α MAP kinase/ nuclear factor-κB pathway. However, we detected Tlr4 expression also in corticotroph (AtT20) and gonadotroph (αT3–1) cell lines suggesting that Tlr4 is also expressed in endocrine epithelial pituitary tumour cells. Therefore we looked for Tlr4 expression in 3 normal human pituitaries and in 67 pituitary adenomas. By in situ hybridisation and immunohistochemistry, sporadic Tlr4 mRNA and protein expression was detected in all endocrine cell types of aIl 3 normal pituitaries. A highly variable expression of Tlr4 mRNA and protein was observed in epithelial cells in 30% of hormone-inactive adenomas, in 47% of somatotroph tumors, in 33% of lactotroph neoplasias and in 50% of corticotroph and thyreotroph adenomas. Since most pituitary adenomas produce IL-6, the effect of LPS on intratumoral IL-6 secretion was investigated in primary cell cultures of pituitary adenomas. In 9 IL-6-producing adenomas expressing Tlr4, the IL-6 release was enhanced dramatically by LPS in a dose- and -time-dependent manner. The specific p38α MAP kinase inhibitor SB203580 dose-dependently suppressed the LPS-induced IL-6 secretion indicating that the signal transduction pathway might be similar to FS cells. Moreover, dexamethasone dose-dependently inhibited LPS-induced IL-6 production in all pituitary adenoma cell cultures. Since IL-6 is supposed to represent a growth factor of pituitary adenoma cells, we speculate that bacterial endotoxins could support pituitary tumour progression in a subset of Tlr4-expressing adenomas during infectious or inflammatory processes and that cortisol may act protective under these conditions.

Effect of bacterial endotoxin on secretion and synthesis of vasopressin during saline load in rats.

Secretion and synthesis of vasopressin was studied in adult male Wistar rats receiving lipopolysaccharide in a dose of 250 microg/100 g body weight and subjected to moderate osmotic stimulation (2% NaCl perorally for 6 days). Lipopolysaccharide stimulated secretion of vasopressin into the blood. It should be emphasized that the content of vasopressin mRNA in gigantocellular nuclei of the hypothalamus decreased, which probably reflected intensification of its translation. The observed changes and slight increase in transcription of the vasopressin gene (determined by the content of heterogeneous nuclear RNA) provide intensive secretion of this neurohormone into the blood.

The Effect Of Bacterial Endotoxin On The Early Tensile Strength Of Healing Surgical Wounds

The Effect Of Bacterial Endotoxin On The Early Tensile Strength Of Healing Surgical Wounds

Effect of bacterial endotoxin and middle ear effusion on ciliary activity: implications for otitis media.

Otitis media with effusion (OME) is the most common cause of childhood deafness. The pathogenesis is not fully understood, especially the reasons for failure of mucociliary clearance of the middle ear. It is not clear whether the cilia function normally in the middle ear and eustachian tube in the chronic phase of otitis media with effusion. However, impaired ciliary function in primary ciliary dyskinesia is known to be frequently associated with the development of otitis media with effusion. We hypothesized that endotoxin or the bacterial products in middle ear fluid in otitis media with effusion would adversely affect ciliary activity, thereby contributing to the pathogenesis of the disease. Laboratory-based study of human ciliary activity with reference to otitis media with effusion. We have studied the activity of human adenoidal cilia under various conditions. Ciliary activity in the presence of Haemophilus influenzae endotoxin additions (at varying concentrations) to cultured adenoidal explants has been measured. In addition, ciliary activity of these explants was also observed after addition of middle ear effusion aspirated from patients. We have shown that endotoxin in concentrations far in excess of those found in the middle ear with chronic otitis media with effusion had no effect on ciliary activity. Furthermore, ciliary activity was completely unaffected by the presence of middle ear effusion. There is no evidence that ciliary activity is reduced by the constituents of middle ear fluid in chronic otitis media with effusion.

Effects of bacterial endotoxin (lipopolysaccharides) on survival and metabolism of cultured precision-cut rat liver slices

The effect of bacterial endotoxin (lipopolysaccharides from Escherichia coli, LPS) on cellular metabolism and drug biotransformation was studied in precision-cut rat liver slices (PCLS). Xenobiotic metabolism by PCLS was assessed by measuring phase I (midazolam hydroxylation) and phase II (paracetamol conjugates) enzyme activities. Nitrites formation was used as an indirect way to assess LPS-mediated activation of nitric oxide synthase (iNOS, type 2). PCLS incubation with various LPS doses results in a dose-dependent formation of nitrites. Such a nitrite formation is decreased by dexamethasone. After incubation of PCLS for 24 h LPS addition did not increase the basal nitrite formation, indicating that cells are not responsive any more. Paracetamol conjugation was unaffected by LPS treatment but midazolam hydroxylation was reduced by more than 50%. Such a loss is not due to cell impairment since neither survival (LDH leakage) nor cellular metabolism (protein synthesis or ATP content) were modified by LPS. Indeed, under defined conditions, namely Williams' medium E and O 2/CO 2 (95:5), PCLS maintained both ATP and GSH levels and the capacity of hepatocytes to synthesize proteins. In conclusion, the in vitro model of PCLS reproduces the inhibitory effect of LPS on a CYP3A-dependent activity, allowing a mechanistic approach to study cell–cell interactions.

The Effect of Bacterial Endotoxin on the Early Tensile Strength of Healing Surgical Wounds

Wound healing in the oral cavity occurs in a bacteria-rich environment, which may affect its outcome. Furthermore, it takes place where forces are frequently applied to the healing tissue. The effect of bacterial endotoxin on the development of tensile strength in healing wounds was studied using surgical skin wounds in rats as a model. Collagen membranes soaked with 0.01 microg of bacterial endotoxin were inserted into surgical skin wounds, and their effect was studied on days 6 and 10. Membranes with no endotoxin served as controls. Endotoxin inhibited the early development of tensile strength in 6 days, healing wounds by 38%, whereas the collagen membrane alone had no effect. Dexamethasone (0.5 mg/kg every 72 h) had a suppressive effect on the development of tensile strength in healing noncontaminated wounds, but not in those containing bacterial endotoxin. These results suggest that bacterial endotoxin may interfere with the early healing of wounds. Understanding the mechanisms of this inhibition may result in treatments that will allow this response to be faster and more reproducible.

Age-related differences in the effects of bacterial endotoxin (LPS) upon the release of LHRH, gonadotropins and hypothalamic inhibitory amino acid neurotransmitters measured in tissues explanted from intact male rats.

In adult rats, bacterial endotoxin (lipopolysaccharide or LPS) is known to diminish the activity of the reproductive axis, mainly by inhibiting luteinizing hormone-releasing hormone (LHRH) secretion; until now, this effect has not been studied in immature rats. The aim of the present study was to evaluate the effect of LPS 1) on LHRH output (and associated changes in the release of inhibitory amino acid neurotransmitters such as gamma-aminobutyric acid (GABA) and taurine) by superfused hypothalamic fragments, and 2) on gonadotropin secretion by incubated hemipituitaries, obtained from young adult (60-day-old) and peripubertal (30-day-old) intact male rats. In adult animals, LPS induced a significant inhibition (50% of basal values) of LHRH release, accompanied by an increase in GABA and taurine output. In juvenile rats the inhibition of LHRH secretion by LPS attained 90% of basal values (p<0.0001 versus adult rats), and the concurrent increase in GABA release was significantly greater (p<0.0001 versus adult rats). LPS did not affect in vitro gonadotropin secretion in adult animals. Conversely, the release of these hormones was significantly (p<0.001 and <0.02 for LH and FSH, respectively) reduced in 30-day-old rats. Our results demonstrate the existence of age-related differences in the effect of LPS on LHRH and gonadotropin secretion. These differences might well be attributed to an increased activity of the hypothalamic GABAergic system. Furthermore, the participation of other factors known to play a role in immune-neuroendocrine relationships (e.g., corticotropin-releasing hormone, testosterone) is discussed.