leukotriene-c4 and Escherichia-coli-Infections

The effect of leukotriene (LT) C4 (LTC4) and LTD4 on the contractility of an inflamed porcine uterus was investigated. On Day 3 of the estrous cycle (Day 0 of the study), either saline or Escherichia coli suspension was injected into each uterine horn. Although acute endometritis developed in all bacteria-inoculated gilts, a severe acute endometritis was noted more often on Day 8 than on Day 16. Myometrial and endometrial/myometrial strips were incubated with LTC4 or LTD4 alone, or together with a cysteinyl-LT receptor antagonist (BAY-u9773). Leukotriene C4 increased the contraction intensity in the saline- and bacteria-treated uteri on Day 8; however, its effect was lower in the myometrium of inflamed uteri. Contraction frequency was found to decrease in the saline-treated uteri as opposed to inflamed ones, in which it was elevated. On Day 16, contraction intensity increased in response to LTC4 in the saline-treated uteri but was reduced in the inflamed organs. The value of this parameter was lower in the inflamed uteri than that in the saline-treated ones. Leukotriene D4 (Days 8 and 16) augmented contractility in the saline-treated uteri, but despite increasing its intensity in the inflamed organs, it decreased contraction frequency. Leukotriene C4 or LTD4, added to BAY-u9773-pretreated saline- and bacteria-treated uteri on both days, decreased the contraction intensity. On Day 16 after treatment with BAY-u9773 and LTC4, contraction intensity in the endometrium/myometrium of the inflamed uteri was lower than that in the saline-treated organs. Data show that both LTC4 and LTD4 affect the contractility of inflamed porcine uteri, though LTC4 exerts a weaker contractile effect.

Topics: Animals; Endometritis; Endometrium; Escherichia coli; Escherichia coli Infections; Female; Leukotriene C4; Leukotriene D4; Myometrium; SRS-A; Sus scrofa; Swine; Swine Diseases; Uterine Contraction

Shiga toxin-producing Escherichia coli (STEC) is a food-borne pathogen that causes hemorrhagic colitis. Under some circumstances, Shiga toxin (Stx) produced within the intestinal tract enters the bloodstream, leading to systemic complications that may cause the potentially fatal hemolytic-uremic syndrome (HUS). Despite STEC human infection is characterized by acute inflammation of the colonic mucosa, little is known regarding the role of proinflammatory mediators like cysteine leukotrienes (cysLTs) in this pathology. Thus, the aim of this work was to analyze whether leukotriene C4 (LTC4) influences STEC pathogenesis in mice. We report that exogenous LTC4 pretreatment severely affected the outcome of STEC gastrointestinal infection. LTC4-pretreated (LTC4+) and STEC-infected (STEC+) mice showed an increased intestinal damage by histological studies, and a decreased survival compared to LTC4-non-pretreated (LTC4-) and STEC+ mice. LTC4+/STEC+ mice that died after the infection displayed neutrophilia and high urea levels, indicating that the cause of death was related to Stx2-toxicity. Despite the differences observed in the survival between LTC4+ and LTC4- mice after STEC infection, both groups showed the same survival after Stx2-intravenous inoculation. In addition, LTC4 pretreatment increased the permeability of mucosal intestinal barrier, as assessed by FITC-dextran absorption experiments. Altogether these results suggest that LTC4 detrimental effect on STEC infection is related to the increased passage of pathogenic factors to the bloodstream. Finally, we showed that STEC infection per se increases the endogenous LTC4 levels in the gut, suggesting that this inflammatory mediator plays a role in the pathogenicity of STEC infection in mice, mainly by disrupting the mucosal epithelial barrier.

Topics: Animals; Disease Models, Animal; Disease Susceptibility; Escherichia coli Infections; Hemolytic-Uremic Syndrome; Intestines; Leukotriene C4; Mice, Inbred BALB C; Shiga-Toxigenic Escherichia coli; Survival Analysis

Leukotrienes (LTs) are lipid mediators that play a significant role in the inflammatory process. Their production in inflamed uteri is not fully understood. The present experiment aimed to determine LTB4 and LTC4 amounts, 5-lipooxygenase (5-LO), LTA4 hydrolase (LTAH) and LTC4 synthase (LTCS) mRNA levels and protein expression in inflamed porcine uteri. On Day 3 of the oestrous cycle (Day 0 of the study), either Escherichia coli suspension or saline were infused into uterine horns. Collection of uterine tissues and washings took place eight or sixteen days later. In gilts suffering from endometritis increased LTB4 and LTC4 levels in the endometrium and washings and 5-LO mRNA levels in the myometrium on Days 8 and 16, 5-LO protein levels in the endometrium and myometrium on Day 8, LTAH mRNA and protein levels in the endometrium and myometrium on Days 8 and 16, respectively. Although LTCS mRNA and protein expression in the myometrium and LTCS protein expression in the endometrium were enhanced on Day 16 after Escherichia coli inoculation, LTCS mRNA levels decreased on Day 8 in both tissues. Our study shows the upregulation of LT production in inflamed porcine uteri, which suggests the importance of these factors to the process of uterine inflammation.

Topics: Animals; Arachidonate 5-Lipoxygenase; Endometritis; Endometrium; Epoxide Hydrolases; Escherichia coli Infections; Female; Glutathione Transferase; Leukotriene B4; Leukotriene C4; Leukotrienes; Myometrium; RNA, Messenger; Sus scrofa; Swine; Swine Diseases; Therapeutic Irrigation; Time Factors; Up-Regulation

We studied the effect of lipopolysaccharide (LPS), proinflammatory cytokines (tumor necrosis factor α [TNF-α] and interleukin [IL]-1β), and anti-inflammatory cytokines (IL-4 and IL-10) on leukotriene (LT) A4 hydrolase and LTC4 synthase (LTCS) protein expression in, and LTB4 and LTC4 secretion from, an inflamed porcine endometrium. On day 3 of the estrous cycle (day 0 of the study), 50 mL of either saline or Escherichia coli suspension (10(9) CFU/mL) was injected into each uterine horn of gilts (n = 12 per group). Endometrial explants, obtained 8 and 16 days later, were incubated for 24 h with LPS (10 or 100 ng/mL of medium), TNF-α, IL-1β, IL-4, and IL-10 (each cytokine: 1 or 10 ng/mL of medium). Although acute endometritis developed in all bacteria-inoculated gilts, a severe form of acute endometritis was diagnosed more often on day 8 of the study than on day 16. The amount of the LTA4 hydrolase (LTAH) protein in the inflamed endometrium on day 8 was greater after applying the lower dose of TNF-α (P < 0.001) and both doses of IL-1β (P < 0.001) and IL-4 (1 ng, P < 0.01 and 10 ng, P < 0.001) than in the saline-treated uteri. A similar situation was observed in the case of the inflamed tissue on day 16 in response to LPS (100 ng, P < 0.01), TNF-α (10 ng, P < 0.05), and IL-4 (1 ng, P < 0.001). The content of LTC4 synthase in the inflamed endometrium on day 8 was reduced by LPS (100 ng, P < 0.05), IL-1β (10 ng, P < 0.05), IL-4 (1 and 10 ng, P < 0.05), and IL-10 (1 ng, P < 0.01) but increased after the application of LPS (100 ng, P < 0.05) and TNF-α (1 and 10 ng, P < 0.001), IL-1β, and IL-4 (1 ng, P < 0.05 and 10 ng, P < 0.001) on day 16. On day 8, endometrial secretion of LTB4 from the saline-injected and E coli-injected organs was similar in response to all of the used mediators. On the other hand, the contents of LTB4 in the medium decreased after incubating the inflamed tissues from day 16 with TNF-α (1 ng, P < 0.05 and 10 ng, P < 0.01), IL-1β (1 ng, P < 0.01), and IL-10 (10 ng, P < 0.05) compared with the saline-treated ones. Secretion of LTC4 from the inflamed uteri on day 8 was elevated by the lower doses of TNF-α (P < 0.01) and IL-10 (P < 0.05), whereas on day 16, such an effect occurred in response to the higher doses of IL-4 (P < 0.01) and IL-10 (P < 0.05). The obtained results show that pro- and anti-inflammatory mediators participate in the synthesis/secretion of LTs from an inflamed porcine endometrium. Our data suggest that inflammatory mediators

Topics: Animals; Cytokines; Endometriosis; Endometrium; Epoxide Hydrolases; Escherichia coli Infections; Female; Gene Expression Regulation; Glutathione Transferase; Inflammation; Leukotriene B4; Leukotriene C4; Lipopolysaccharides; Swine; Swine Diseases

Stimulated mast cells release a variety of chemotactic factors such as tumor necrosis factor alpha (TNF-alpha) and leukotriene B4. Recent studies have shown that mast cell-derived TNF-alpha plays a critical role in host defense against Gram negative bacterial infections by the recruitment of neutrophils to the sites of infection. In the present study, we sought to investigate if mast cells release leukotriene (LT) B4 in response to bacteria and, if so, to establish its in vivo relevance. We show that mast cells release significant amounts of LTB4 and LTC4 in response to exposure to FimH-expressing type 1 fimbriated Escherichia coli in vitro. To test the functional significance of mast cell-derived LTs during an E. coli infection in vivo, we examined the effect of a LT-synthesis inhibitor, A-63162, on bacterial clearance and neutrophil influx in an infectious peritonitis model in mast cell-deficient mice (WBB6F1-W/WV) and their normal congenic control (WBB6F1-+/+) mice. Our results show that a treatment with A-63162 reduced neutrophil influx and bacterial clearance in the peritoneal cavities of mast cell-sufficient but not -deficient mice. Thus, mast cell-derived LTs contribute to host defense by mediating early neutrophil influx and bacterial clearance at sites of infection.

Topics: Adhesins, Bacterial; Adhesins, Escherichia coli; Animals; Cells, Cultured; Escherichia coli; Escherichia coli Infections; Fimbriae Proteins; Leukotriene B4; Leukotriene C4; Male; Mast Cells; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Neutrophils; Peritonitis