LTB4 Levels Research Articles

Use of a balanced dual cyclooxygenase-1/2 and 5-lypoxygenase inhibitor in experimental colitis

Cyclooxygenase (COX) and 5-lipoxygenase (5-LOX) play an important role in inflammatory bowel diseases (IBDs). We investigated the effects of flavocoxid, a dual COX/LOX inhibitor, in experimental colitis induced with either dinitrobenzenesulfonic acid (DNBS) or dextrane sulphate sodium (DSS)In the first model, colitis was induced in rats by a single intra-colonic instillation (25mg in 0.8ml 50% ethanol) of DNBS; after 24h animals were randomized to receive orally twice a day, flavocoxid (10mg/kg), zileuton (50mg/kg), or celecoxib (5mg/kg). Sham animals received 0.8ml of saline by a single intra-colonic instillation. Rats were killed 4 days after induction and samples were collected for analysis. In the second model, colitis was induced in rats by the administration of 8% DSS dissolved in drinking water; after 24h animals were randomized to the same above reported treatments. Sham animals received standard drinking water. Rats were killed 5 days after induction and samples were collected for analysis.Flavocoxid, zileuton and celecoxib improved weight loss, reduced colonic myeloperoxydase activity, macroscopic and microscopic damage, and TNF-α serum levels. Flavocoxid and celecoxib also reduced malondialdheyde, 6-keto PGF1α and PGE-2 levels while flavocoxid and zileuton decreased LTB-4 levels. In addition, flavocoxid treatment improved histological features and apoptosis as compared to zileuton and celecoxib; moreover only flavocoxid reduced TXB2, thus avoiding an imbalance in eicosanoids production.Our results show that flavocoxid has protective effect in IBDs and may represents a future safe treatment for inflammatory bowel diseases.

Relationship between metabolites of arachidonic acid and prognosis in patients with acute coronary syndrome

ObjectiveTo investigate the correlation of arachidonic acid (ARA) metabolites and prognosis in ACS patients. Methods and resultsThis is a mono-center retrospective nested case-control study. We followed up 470 ACS patients, of whom 39 patients had MACE in a mean follow up time of 1037days (identified as MACE group). Another 39 clinically matched patients without MACE were selected from the 470 ACS patients (Non-MACE group). Thirty-nine subjects without Coronary Heart Disease were enrolled as Control group. Metabolites of ARA were determined by LC-MS/MS. We found that plasma levels of LTB4, 8-HETE, 11-HETE, 12-HETE, and 15-HETE were significantly increased in MACE and Non-MACE groups, 5-HETE and 9-HETE were significantly increased in MACE group comparing with Control group (P<0.05). Importantly, plasma level of 19-HETE in MACE group was significantly lower than Non-MACE and Control groups. 19-HETE significantly correlated with the prognosis of ACS after adjustment for clinical characteristics (HR=0.103, 95% C.I.: 0.014–0.766). The AUC for ROC curve of 19-HETE in predicting MACE was 0.637 (P<0.05). Survival analysis showed that ACS patients with 19-HETE levels higher than 0.13ng/ml tend to have better prognosis than those lower than 0.13ng/ml (P<0.05). GRACE score and serum Fib levels were also significantly correlated with MACE. 20-HETE level was found significantly higher in STEMI group comparing with NSTE-ACS group (P<0.05). ConclusionPlasma arachidonic acid metabolites may act as prognostic markers for ACS patients.

Aberrant localized LTB4 production exacerbates methicillin-resistant Staphylococcus aureus skin infection in diabetic mice.

Abstract A major cause of severe skin infections is methicillin-resistant Staphylococcus aureus (MRSA). Immunotherapeutic strategies are needed to treat infections. Neutrophils and macrophages control MRSA skin infection but undue inflammation causes injury. The bioactive eicosanoid leukotriene B4 is a potent chemoattractant and enhances phagocyte effector functions in naïve mice. However we have shown that diabetic mice produce chronic LTB4 which promotes susceptibility to sepsis but the role of LTB4 in localized infections is unknown. We hypothesize that aberrant LTB4 drive excessive inflammation during MRSA skin infection in diabetics. Diabetic mice at day 1 post infection had larger infected areas, bacterial and apoptotic cell burdens than nondiabetic controls. By intravital microscopy we observed more neutrophil recruitment in diabetic mice. These effects correlated with high levels of LTB4 and its receptor BLT1. At day 9 post infection nondiabetic mice were nearly healed but diabetic mice still had cell infiltration, high bacterial and apoptotic burdens, which associated with high levels of inflammatory mediators. To test whether chronic LTB4 causes uncontrolled infection, diabetic mice were treated daily with a topical ointment containing BLT1 antagonist. The treatment reduced infection area, bacterial burden and neutrophil recruitment. We also detected fewer apoptotic cells and lower expression of inflammatory mediators. These findings reveal that LTB4 is detrimental for diabetics by chronically inducing a damaging inflammatory response. We observe that topical BLT1 antagonist treatment improves host defense in diabetic mice and promises to be an effective therapeutic to treat MRSA infections in diabetic patients.

The natural dual cyclooxygenase and 5-lipoxygenase inhibitor flavocoxid is protective in EAE through effects on Th1/Th17 differentiation and macrophage/microglia activation

Prostaglandins and leukotrienes, bioactive mediators generated by cyclooxygenases (COX) and 5-lipoxygenase (5-LO) from arachidonic acid, play an essential role in neuroinflammation. High levels of LTB4 and PGE2 and increased expression of COX and 5-LO, as well as high expression of PGE2 receptors were reported in multiple sclerosis (MS) patients and in experimental autoimmune encephalomyelitis (EAE). Prostaglandins and leukotrienes have an interdependent and compensatory role in EAE, which led to the concept of therapy using dual COX/5-LO inhibitors. The plant derived flavocoxid, a dual COX/5-LO inhibitor with anti-inflammatory and antioxidant properties, manufactured as a prescription pharmaconutrient, was reported to be neuroprotective in models of transient ischemic stroke and brain injury. The present study is the first report on prophylactic and therapeutic effects of flavocoxid in EAE. The beneficial effects correlate with reduced expression of proinflammatory cytokines and of COX2 and 5-LO in spinal cords and spleens of EAE mice. The protective mechanisms include: 1. reduction in expression of MHCII/costimulatory molecules and production of proinflammatory cytokines; 2. promotion of the M2 phenotype including IL-10 expression and release by macrophages and microglia; 3. inhibition of Th1 and Th17 differentiation through direct effects on T cells. The direct inhibitory effect on Th1/Th17 differentiation, and promoting the development of M2 macrophages and microglia, represent novel mechanisms for the flavocoxid anti-inflammatory activity. As a dual COX/5-LO inhibitor with antioxidant properties, flavocoxid might be useful as a potential therapeutic medical food agent in MS patients.

The Effectiveness of Anti-leukotriene Agents in Patients with COPD: A Systemic Review and Meta-analysis.

Anti-leukotriene (anti-LT) agents have been not yet established for effectiveness in patients with chronic obstructive pulmonary disease (COPD). We performed a systematic review and meta-analysis to assess whether anti-LT agents have the responsiveness for COPD patients. MEDLINE, EMBASE, Cochrane Central Register, and Korea Med were searched for relevant clinical trials to review. Seven studies involving 342 patients were finally analyzed. Pooled estimation from three randomized controlled studies did not demonstrate that anti-LT agents increased forced expiratory volume in 1s [overall effect: 0.09L, 95% confidence interval (CI) -0.04 to 0.21; P=0.17; I (2) =41.0%] or forced vital capacity (overall effect: 0.04L, 95% CI -0.04 to 0.11; P=0.64; I (2)=0.0%). As for inflammatory markers, anti-LT agents did not affect the level of myeloperoxidase (standardized mean difference, -0.15; 95% CI -0.65 to 0.36) or LTB4 (standardized mean difference, -0.41; 95% CI -0.96 to 0.13). They reduced the frequency of dyspnea [relative risk (RR) 0.43; 95% CI 0.29 to 0.64] and sputum (RR 0.37; 95% CI 0.22 to 0.63), based on overall estimation from two non-randomized studies. However, our review revealed that there are few well-designed, randomized controlled studies with large sample sizes and long treatment durations. Although symptomatic improvements were demonstrated in some studies, there is a lack of evidence to support the therapeutic efficacy of anti-LT agents in patients with COPD. Further large-scale, long-term studies are needed to identify predictive factors for COPD patients who may benefit from anti-LT agents.

LTB4 promotes insulin resistance in obese mice by acting on macrophages, hepatocytes and myocytes.

Chronic inflammation is a key component of obesity–induced insulin resistance and plays a central role in metabolic disease. In this study, we found that the major insulin target tissues, liver, muscle and adipose tissue exhibit increased levels of the chemotactic eicosanoid LTB4 in obese high fat diet (HFD) mice compared to lean chow fed mice. Inhibition of the LTB4 receptor, Ltb4r1, through either genetic or pharmacologic loss of function results in an anti–inflammatory phenotype with protection from systemic insulin resistance and hepatic steatosis in the setting of both HFD–induced and genetic obesity. Importantly, in vitro treatment with LTB4 directly enhanced macrophage chemotaxis, stimulated inflammatory pathways in macrophages, promoted de novo hepatic lipogenesis, decreased insulin stimulated glucose uptake in L6 myocytes, increased gluconeogenesis, and impaired insulin–mediated suppression of hepatic glucose output (HGO) in primary mouse hepatocytes. This was accompanied by decreased insulin stimulated Akt phosphorylation and increased Irs1 and Irs2 serine phosphorylation and all of these events were Gαi and Jnk dependent. Taken together, these observations elucidate a novel role of LTB4/Ltb4r1 in the etiology of insulin resistance in hepatocytes and myocytes, and shows that in vivo inhibition of Ltb4r1 leads to robust insulin sensitizing effects.

Evaluation of Markers of Inflammation and Oxidative Stress in COPD Patients with or without Cardiovascular Comorbidities

Although both chronic obstructive pulmonary disease (COPD) and cardiovascular diseases (CVD) are characterised by chronic, systemic inflammation, their reciprocal interactions are poorly understood. The purpose of this study was to determine the concentrations of both inflammatory and oxidative stress biomarkers in the serum and exhaled breath condensate (EBC) of COPD patients, either with coexisting CVD or without cardio-vascular comorbidities. Twenty-four COPD patients with CVD were allocated to group A, 20 COPD patients without CVD were assigned to group B and 16 healthy patients were included as a control. A medical history and physical examination were performed, and the following were measured: serum CRP concentration, glucose level, uraemic acid level and lipid profile. In addition 8-isoprostane, LTB4 and IL-8 concentrations were measured both in serum and EBC. Spirometry, six-minute walk test and echocardiography were performed in all subjects. EBC concentrations of 8-isoprostane and LTB4, and serum levels of CRP, 8-soprostane, LTB4, IL-8 were significantly higher in COPD patients than in healthy controls. COPD patients with CVD were not found to have higher concentrations of the assessed markers than those without CVD, neither in the serum nor EBC. CRP, 8-isoprostane and LTB4 levels in serum, and IL-8 concentration in EBC correlated negatively with the value of forced expiratory volume in one second. Although systemic inflammation coexists with COPD, it is not elevated in COPD patients with CVD. Since this phenomenon may result from treatment with statins, future studies should state whether COPD patients could benefit from the additional statin therapy.

Protective effects of garlic extract, PMK-S005, against nonsteroidal anti-inflammatory drugs-induced acute gastric damage in rats.

PMK-S005 is synthetic s-allyl-L-cysteine (SAC), a sulfur-containing amino acid, which was initially isolated from garlic. The antioxidant and anti-inflammation activities of SAC have been demonstrated in diverse experimental animal models. The purpose of this study was to investigate the gastroprotective effects of PMK-S005 against NSAIDs-induced acute gastric damage in rats. Eight-week SD rats were pretreated with PMK-S005 (1, 5, or 10mg/kg) or rebamipide (50mg/kg) 1h before administration of NSAIDs including aspirin (200mg/kg), diclofenac (80mg/kg), and indomethacin (40mg/kg). After 4h, the gross ulcer index, histological index, and gastric mucus level were determined. Myeloperoxidase (MPO), TNF-α, IL-1β, PGE2, and LTB4 levels were estimated in the gastric mucosal tissue by ELISA. Protein expressions of cPLA2, COX-1, and COX-2 were assessed by Western blot analysis. Pretreatment with PMK-S005 significantly attenuated the NSAIDs-induced gastric damage and increased the gastric mucus level. In addition, PMK-S005 attenuated increases in MPO, TNF-α, and IL-1β production. The expressions of cPLA2 and COX-2 induced by NSAIDs were decreased by PMK-S005 pretreatment. PMK-S005 did not cause suppression of PGE2 synthesis induced by NSAIDs, but LTB4 production was significantly suppressed by PMK-S005. The effects of PMK-S005 were consistently maximized at a concentration of 5mg/kg, which were frequently superior to those of rebamipide. These results strongly suggest that PMK-S005 can be a useful gastroprotective agent against acute gastric mucosal damage by suppressing proinflammatory cytokines, down-regulating cPLA2, COX-2 and LTB4 expression, and increasing the synthesis of mucus.

Increased of exhaled breath condensate neutrophil chemotaxis in acute exacerbation of COPD

BackgroundNeutrophils have been involved in the pathogenesis of chronic obstructive pulmonary disease (COPD). Underlying mechanisms of neutrophil accumulation in the airways of stable and exacerbated COPD patients are poorly understood. The aim of this study was to assess exhaled breath condensate (EBC) neutrophil chemotactic activity, the level of two chemoattractants for neutrophils (GRO-α and LTB4) during the course of an acute exacerbation of COPD (AECOPD).Methods50 ex smoking COPD patients (33 with acute exacerbation and 17 in stable disease) and 20 matched ex smoking healthy controls were compared. EBC was collected by using a commercially available condenser (EcoScreen®). EBC neutrophil chemotactic activity (NCA) was assessed by using Boyden microchambers. Chemotactic index (CI) was used to evaluate cell migration. LTB4 and GROα levels were measured by a specific enzyme immunoassay in EBC.ResultsStable COPD and outpatients with AECOPD, but not hospitalized with AECOPD, had raised EBC NCA compared to healthy subjects (p < 0.05 and p < 0.01 respectively). In outpatients with AECOPD EBC NCA significantly decreased 6 weeks after the exacerbation. Overall EBC NCA was weakly correlated with sputum neutrophil counts (r = 0.26, p < 0.05).EBC LTB4 levels were increased in all groups of COPD compared to healthy subjects while GRO-α was only raised in patients with AECOPD. Furthermore, EBC LTB4 and GRO-α significantly decreased after recovery of the acute exacerbation. Increasing concentrations (0.1 to 10 μg/mL) of anti- human GRO-α monoclonal antibody had no effect on EBC neutrophil chemotactic activity of 10 exacerbated COPD patients.ConclusionsEBC NCA rose during acute exacerbation of COPD in ambulatory patients and decreased at recovery. While LTB4 seems to play a role both in stable and in exacerbated phase of the disease, the role of GRO-α as a chemotactic factor during AECOPD is not clearly established and needs further investigation.

Interrelationships between ALOX5AP polymorphisms, serum leukotriene B4 level and risk of acute coronary syndrome.

BackgroundWe investigated the relationships between the ALOX5AP gene rs10507391 and rs4769874 polymorphisms, serum levels of leukotriene (LT) B4, and risk of acute coronary syndrome (ACS).MethodsA total of 709 participants, comprising 508 ACS patients (ACS group) and 201 noncoronary artery disease patients with chest pain (control group) were recruited from the Han population of the Changwu region in China. Two polymorphic loci were genotyped using polymerase chain reaction and restriction fragment length polymorphism analysis. Serum LTB4 level was determined by enzyme-linked immunosorbent assay.ResultsSerum LTB4 levels were significantly higher (P<0.001) in the ACS group (median/interquartile range, 470.27/316.32 pg/ml) than in the control group (233.05/226.82 pg/ml). No statistical differences were observed between genotype, allele and haplotype frequencies for the tested loci in either the ACS group or the control group, even after adjustments were made for conventional risk factors by multivariate logistic regression. This suggests there is no association between the ALOX5AP rs10507391 and rs4769874 polymorphisms and ACS risk. Elevated serum LTB4 level was closely linked to ACS risk, and may be independent of traditional risk factors as a risk factor for ACS (P<0.001). There was no significant association between serum LTB4 levels and the two variants in either the ACS group or the control group.ConclusionsRs10507391, rs4769874 and its haplotypes in ALOX5AP are unrelated to ACS risk in the Chinese Han population of Changwu, but elevated serum LTB4 level is strongly associated with ACS risk. Serum LTB4 level is not subject to the influence of either the rs10507391, rs4769874 or the haplotype.

Low leukotriene B4 receptor 1 leads to ALOX5 downregulation at diagnosis of chronic myeloid leukemia.

ALOX5 is implicated in chronic myeloid leukemia development in mouse leukemic stem cells, but its importance in human chronic myeloid leukemia is unknown. Functional ALOX5 was assessed using an LTB4 ELISA and ALOX5, and LTB4R1 mRNA expression was determined via a TaqMan gene expression assay. LTB4R1 and 5-LOX protein levels were assessed by cell surface flow cytometry analysis. At diagnosis ALOX5 was below normal in both blood and CD34(+) stem cells in all patients. On treatment initiation, ALOX5 levels increased in all patients except those who were destined to progress subsequently to blast crisis. LTB4 levels were increased despite low ALOX5 expression, suggesting that the arachidonic acid pathway is functioning normally up to the point of LTB4 production. However, the LTB4 receptor (BLT1) protein in newly diagnosed patients was significantly lower than after a period of treatment (P<0.0001). The low level of LTB4R1 at diagnosis explains the downregulation of ALOX5. In the absence of LTB4R1, the arachidonic acid pathway intermediates (5-HEPTE and LTA4) negatively regulate ALOX5. ALOX5 regulation is aberrant in chronic myeloid leukemia patients and may not be important for the development of the disease. Our data suggest caution when extrapolating mouse model data into human chronic myeloid leukemia.

Topical application of the adenosine A2A receptor agonist CGS-21680 prevents phorbol-induced epidermal hyperplasia and inflammation in mice.

The nucleoside adenosine is a known regulator of immunity and inflammation that mediates, at least in part, the anti-inflammatory effect of methotrexate, an immunosuppressive agent widely used to treat autoimmune inflammatory diseases. Adenosine A2A receptors play a key role in the inhibition of the inflammatory process besides promoting wound healing. Therefore, we aimed to determine the topical effect of a selective agonist, CGS-21680, on a murine model of skin hyperplasia with a marked inflammatory component. Pretreatment with either CGS-21680 (5μg per site) or the reference agent dexamethasone (200μg/site) prevented the epidermal hyperplasia and inflammatory response induced by topical application of 12-O-tetradecanoylphorbol-13-acetate (TPA, 2nmol/site) for three consecutive days. The histological analysis showed that both CGS-21680 and dexamethasone produced a marked reduction of inflammatory cell infiltrate, which correlated with diminished myeloperoxidase (MPO) activity in skin homogenates. Both treatments reduced the levels of the chemotactic mediators LTB4 and CXCL-1, and the inflammatory cytokine TNF-α, through the suppression of NFκB phosphorylation. The immunohistochemical analysis of the hyperproliferative markers cytokeratin 6 (CK6) and Ki67 revealed that while both agents inhibit the number of proliferating cells in the epidermis, CGS-21680 treatment promoted dermal fibroblasts proliferation. Consistently, increased collagen deposition in dermis was observed in tissue sections from agonist-treated mice. Our results showed that CGS 21680 efficiently prevents phorbol-induced epidermal hyperplasia and inflammation in mice without the deleterious atrophic effect of topical corticosteroids.

In vivo sex differences in leukotriene biosynthesis in zymosan-induced peritonitis

Leukotrienes (LTs) are 5-lipoxygenase (5-LO) metabolites which are implicated in sex-dependent inflammatory diseases (asthma, autoimmune diseases, etc.). We have recently reported sex differences in LT biosynthesis in in vitro models such as human whole blood, neutrophils and monocytes, due to down-regulation of 5-LO product formation by androgens. Here we present evidences for sex differences in LT synthesis and related inflammatory reactions in an in vivo model of inflammation (mouse zymosan-induced peritonitis). On the cellular level, differential 5-LO subcellular compartmentalization in peritoneal macrophages (PM) from male and female mice might be the basis for these differences. Sex differences in vascular permeability and neutrophil recruitment (cell number and myeloperoxidase activity) into peritoneal cavity were evident upon intraperitoneal zymosan injection, with more prominent responses in female mice. This was accompanied by higher levels of LTC4 and LTB4 in peritoneal exudates of female compared to male mice. Interestingly, LT peritoneal levels in orchidectomized mice were higher than in sham male mice. In accordance with the in vivo results, LT formation in stimulated PM from female mice was higher than in male PM, accompanied by alterations in 5-LO subcellular localization. The increased formation of LTC4 in incubations of PM from orchidectomized mice confirms a role of sex hormones. In conclusion, sex differences observed in LT biosynthesis during peritonitis in vivo may be related, at least in part, to a variant 5-LO localization in PM from male and female mice.

Leukotriene B4 dictates sterile inflammation in type 1 diabetes (INM7P.424)

Abstract Type 1 diabetes (T1D) is characterized by chronic systemic inflammation that could be involved in the enhanced susceptibility to sepsis. The IL-1b/IL-1bR axis drives inflammation in a MyD88-dependent manner, but the molecular mechanisms involved in IL-1b actions in macrophages during T1D are unknown. We hypothesized that leukotriene (LT) B4 promotes IL-1b responsiveness in T1D by enhancing MyD88 expression. Peritoneal macrophages (PMs) from T1D mice expressed higher levels of MyD88 and its transcription factor STAT-1 than PMs from nondiabetic mice. 5-LO expression, LTB4 synthesis and IL-1b levels were also increased in both PM and serum from T1D mice. In vitro and in vivo insulin treatment restored LTB4 and STAT-1/MyD88 levels. Genetic and pharmacologic inhibition of the LTB4/BLT1 axis abolished MyD88 and STAT-1 induction in diabetic mice. ChIP assay showed that AP-1/cJun drove basal STAT-1 levels in an LTB4-dependent manner in T1D. We speculated that high LTB4 levels contribute to enhanced susceptibility to sepsis in T1D. Compared to WT or untreated T1D mice, genetic and pharmacologic inhibition of 5-LO prolonged T1D mice survival after polymicrobial sepsis; associated with decreased blood bacteria and reduced production of proinflammatory cytokines. We conclude that LTB4, by increasing MyD88 and IL-1b levels in a c-Jun/STAT-1 dependent manner, is the driving force involved in inflammation associated with T1D that contributes to high mortality associated to sepsis T1D.

Air pollution and subclinical airway inflammation in the SALIA cohort study

BackgroundThe association between long-term exposure to air pollution and local inflammation in the lung has rarely been investigated in the general population of elderly subjects before. We investigated this association in a population-based cohort of elderly women from Germany.MethodsIn a follow-up examination of the SALIA cohort study in 2008/2009, 402 women aged 68 to 79 years from the Ruhr Area and Borken (Germany) were clinically examined. Inflammatory markers were determined in exhaled breath condensate (EBC) and in induced sputum (IS). We used traffic indicators and measured air pollutants at single monitoring stations in the study area to assess individual traffic exposure and long-term air pollution background exposure. Additionally long-term residential exposure to air pollution was estimated using land-use regression (LUR) models. We applied multiple logistic and linear regression analyses adjusted for age, indoor mould, smoking, passive smoking and socio-economic status and additionally conducted sensitivity analyses.ResultsInflammatory markers showed a high variability between the individuals and were higher with higher exposure to air pollution. NO derivatives, leukotriene (LT) B4 and tumour necrosis factor-α (TNF-α) showed the strongest associations. An increase of 9.42 μg/m3 (interquartile range) in LUR modelled NO2 was associated with measureable LTB4 level (level with values above the detection limit) in EBC (odds ratio: 1.38, 95% CI: 1.02 -1.86) as well as with LTB4 in IS (%-change: 19%, 95% CI: 7% - 32%). The results remained consistent after exclusion of subpopulations with risk factors for inflammation (smoking, respiratory diseases, mould infestation) and after extension of models with additional adjustment for season of examination, mass of IS and urban/rural living as sensitivity analyses.ConclusionsIn this analysis of the SALIA study we found that long-term exposure to air pollutants from traffic and industrial sources was associated with an increase of several inflammatory markers in EBC and in IS. We conclude that long-term exposure to air pollution might lead to changes in the inflammatory marker profile in the lower airways in an elderly female population.

Leukotriene B4 levels in human atherosclerotic plaques and abdominal aortic aneurysms.

BackgroundLeukotriene B4 (LTB4) has been associated with the initiation and progression of atherosclerosis and abdominal aortic aneurysm (AAA) formation. However, associations of LTB4 levels with tissue characteristics and adverse clinical outcome of advanced atherosclerosis and AAA are scarcely studied. We hypothesized that LTB4 levels are associated with a vulnerable plaque phenotype and adverse clinical outcome. Furthermore, that LTB4 levels are associated with inflammatory AAA and adverse clinical outcome.MethodsAtherosclerotic plaques and AAA specimens were selected from two independent databases for LTB4 measurements. Plaques were isolated during carotid endarterectomy from asymptomatic (n = 58) or symptomatic (n = 317) patients, classified prior to surgery. LTB4 levels were measured without prior lipid extraction and levels were corrected for protein content. LTB4 levels were related to plaque phenotype, baseline patient characteristics and clinical outcome within three years following surgery. Seven non-diseased mammary artery specimens served as controls. AAA specimens were isolated during open repair, classified as elective (n = 189), symptomatic (n = 29) or ruptured (n = 23). LTB4 levels were measured similar to the plaque measurements and were related to tissue characteristics, baseline patient characteristics and clinical outcome. Twenty-six non-diseased aortic specimens served as controls.ResultsLTB4 levels corrected for protein content were not significantly associated with histological characteristics specific for vulnerable plaques or inflammatory AAA as well as clinical presentation. Moreover, it could not predict secondary manifestations independently investigated in both databases. However, LTB4 levels were significantly lower in controls compared to plaque (p = 0.025) or AAA (p = 0.017).ConclusionsLTB4 levels were not associated with a vulnerable plaque phenotype or inflammatory AAA or clinical presentation. This study does not provide supportive evidence for a role of LTB4 in atherosclerotic plaque destabilization or AAA expansion. However, these data should be interpreted with care, since LTB4 measurements were performed without prior lipid extractions.

A remarkable Activity of Steroid Biosynthesis in Captopril Preserved Leydig Cells of Mice Implicated Leukotriene B4 and Gonadotropin Releasing Hormones in vitro

In this study, investigated whether captopril inhibited steroidogenesis and components of the Leukotriene B4 pathways are involved in GnRH agonist (GnRH)-induced testis steroidogenesis in mice Leydig cells. Primary cultures of mice Leydig cells were established. Purified Leydig cells from adult albino mice were incubated with gradual various concentrations of GnRH with and without Captopril, Luteinizing hormone (LH); LTB4, steroidogenic (testosterone) activity and LTB4 concentration were measured after various time intervals and Leydig cell viability. The maneuvers of Leydig cells treated media was covered the singular and dual actions of antisteroidogenic of captopril and the reversible activity by GnRH-LTB4 as well as contribution of LTB4 in Leydig cells testosterone production endpoint. The different treatment media are Medium alone; Medium plus captopril 60 μM, 65 μM, 70 μM, 75 μM and 80 μM 100 μM; Medium plus 2.5mU/ml leukotriene B4; Medium plus 0.1 mM LH; Medium plus 0.1 μM GnRH; Medium plus 65 μM captopril plus 2.5 mU/ml leukotriene B4;Medium plus 65 μM captopril plus 0.1 mM LH; Medium plus 65 μM captopril plus 0.1 mM GnRH; Medium plus 0.1 mM GnRH plus 2.5 mU/ml leukotriene B4 and Medium plus 65 μM captopril plus 0.1 mM GnRH plus 2.5 mU/ml leukotriene B4. Basal testosterone levels were maximal at 0.1 μM GnRH concentration and superior testosterone yield in Leydig cells incubated 0.1 μM GnRH media than without GnRH media, and the activity profile LTB4 flow up. That comparable result led to highly correlated approved the contribution of LTB4 in GnRH stimulated Leydig cell steroidogenic end point. Furthermore captopril had an abolishment effect partially of testosterone yield and recovered and improved by GnRH and LTB4. The Leydig cells viability results suggest that the major effect of GnRH is probably beyond the LTB4. The entire key; GnRH induced testosterone production and upregulated LTB4 Levels at both the captopril inhibitory LTB4-testesteron Leydig cells culture media and captopril abolished LTB4 levels; it also activated endogenous LTB4, but not LH motivated testosterone pathway. Our data show that GnRH positively regulates steroidogenesis via LTB4 signaling in mice Leydig cells. LTB4 activation by GnRH may be responsible for the induction of Ca++ signaling indirect. Possibility improve the captopril steroidogenic disruption in Leydig cells via LTB4 and/or GnRH induction of endogenous LTB4, likewise the positive maintenance of Leydig cells viability matched induce testosterone synthesis. The LTB4 production, which may ultimately modulate steroidogenesis in mice Leydig cells, and promise new antidotal and preventative of captopril adverse effects.

A selective antagonist of histamine H4 receptors prevents antigen‐induced airway inflammation and bronchoconstriction in guinea pigs: involvement of lipocortin‐1

Among the pathogenic mechanisms of asthma, a role for oxidative/nitrosative stress has been well documented. Recent evidence suggests that histamine H₄ receptors play a modulatory role in allergic inflammation. Here we report the effects of compound JNJ 7777120 (JNJ), a selective H4 receptor antagonist, on antigen-induced airway inflammation, paying special attention to its effects on lipocortin-1 (LC-1/annexin-A1), a 37 kDA anti-inflammatory protein that plays a key role in the production of inflammatory mediators. Ovalbumin (OA)-sensitized guinea pigs placed in a respiratory chamber were challenged with antigen. JNJ (5, 7.5 and 10 mg.kg⁻¹) was given i.p. for 4 days before antigen challenge. Respiratory parameters were recorded. Bronchoalveolar lavage (BAL) fluid was collected and lung specimens taken for further analyses 1 h after antigen challenge. In BAL fluid, levels of LC-1, PGD2 , LTB4 and TNF-α were measured. In lung tissue samples, myeloperoxidase, caspase-3 and Mn-superoxide dismutase activities and 8-hydroxy-2-deoxyguanosine levels were measured. OA challenge decreased LC-1 levels in BAL fluid, induced cough, dyspnoea and bronchoconstriction and increased PGD2 , LTB4 and TNF-α levels in lung tissue. Treatment with JNJ dose-dependently increased levels of LC-1, reduced respiratory abnormalities and lowered levels of PGD2 , LTB4 and TNF-α in BAL fluid. Antigen-induced asthma-like reactions in guinea pigs decreased levels of LC-1 and increased TNF-α and eicosanoid production. JNJ pretreatment reduced allergic asthmatic responses and airway inflammation, an effect associated with LC-1 up-regulation.

Pivotal Role of the 5-Lipoxygenase Pathway in Lung Injury after Experimental Sepsis

Postsepsis lung injury is a common clinical problem associated with significant morbidity and mortality. Leukotrienes (LTs) are important lipid mediators of infection and inflammation derived from the 5-lipoxygenase (5-LO) metabolism of arachidonate with the potential to contribute to lung damage after sepsis. To test the hypothesis that LTs are mediators of lung injury after sepsis, we assessed lung structure, inflammatory mediators, and mechanical changes after cecal ligation and puncture surgery in wild-type (WT) and 5-LO knockout (5-LO(-/-)) mice and in WT mice treated with a pharmacologic LT synthesis inhibitor (MK886) and LT receptor antagonists (CP105,696 and montelukast). Sixteen hours after surgery, WT animals exhibited severe lung injury (by histological analysis), substantial mechanical impairment (i.e., an increase in static lung elastance), an increase in neutrophil infiltration, and high levels of LTB4, cysteinyl-LTs (cys-LTs), prostaglandin E2, IL-1β, IL-6, IL-10, IL-17, KC (CXCL1), and monocyte chemotactic protein-1 (CCL2) in lung tissue and plasma. 5-LO(-/-) mice and WT mice treated with a pharmacologic 5-LO inhibitor were significantly protected from lung inflammation and injury. Selective antagonists for BLT1 or cys-LT1, the high-affinity receptors for LTB4 and cys-LTs, respectively, were insufficient to provide protection when used alone. These results point to an important role for 5-LO products in sepsis-induced lung injury and suggest that the use of 5-LO inhibitors may be of therapeutic benefit clinically.

Synthesis of leukotrienes in porcine uteri with endometritis induced by infection with Escherichia coli

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.