Leukotrienes and atherosclerosis: new roles for old mediators

Recent advances in function and structure of two leukotriene B4 receptors: BLT1 and BLT2

Leukotriene B₄ (LTB₄) is generated by the enzymatic oxidation of arachidonic acid, which is then released from the cell membrane and acts as a potent activator of leukocytes and other inflammatory cells. Numerous studies have demonstrated the physiological and pathophysiological significance of this lipid in various diseases. LTB₄ exerts its activities by binding to its specific G protein-coupled receptors (GPCRs): BLT1 and BLT2. In mouse disease models, treatment with BLT1 antagonists or BLT1 gene ablation attenuated various diseases, including bronchial asthma, arthritis, and psoriasis, whereas BLT2 deficiency exacerbated several diseases in the skin, cornea, and small intestine. Therefore, BLT1 inhibitors and BLT2 activators could be beneficial for the treatment of several inflammatory and immune disorders. As a result, attractive compounds targeting LTB₄ receptors have been developed by several pharmaceutical companies. This review aims to understand the potential of BLT1 and BLT2 as therapeutic targets for the treatment of various inflammatory diseases. In addition, recent topics are discussed with major focuses on the structure and post-translational modifications of BLT1 and BLT2. Collectively, current evidence on modulating LTB₄ receptor functions provides new strategies for the treatment of various diseases.

Epigenetic regulation mechanism of DNA methylation and miRNAs on the expression of the ALOX5AP gene in patients with ischemic stroke

5-lipoxygenase-activating protein (FLAP), encoded by the arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene, can adjust the biogenesis of proinflammatory leukotrienes to increase the adhesion and permeability of the vascular internal wall. Moreover, it participates in the process of atherosclerosis and is closely associated with ischemic stroke (IS). Accumulating evidence has shown that the expression levels of the ALOX5AP gene are upregulated in patients with IS. However, the mechanism of ALOX5AP action in IS remain elusive. The present study hypothesized that epigenetic regulation, including DNA methylation and microRNA (miR/miRNA) regulation, affects the expression levels of the ALOX5AP gene. Therefore, 200 patients with a first diagnosis of acute IS and 200 healthy control subjects were enrolled in the present study. Initially, the mRNA expression levels of the ALOX5AP gene were examined by reverse transcription-quantitative PCR. It was found that the mRNA levels of ALOX5AP gene in the IS group were significantly higher compared with controls (P<0.05). Subsequently, the methylation status of 17 CpG sites located in the promoter region of ALOX5AP was assessed by MethyTarget sequencing. However, the levels of methylation exhibited no significant differences between IS and control groups (P>0.05). Moreover, the expression levels of miR-335 and miR-495 were examined as two potential miRNAs targeting the ALOX5AP gene. The expression levels of miR-335 and miR-495 in the IS group were significantly lower compared with the control group (P<0.05). Finally, the luciferase assay results indicated that the luciferase activity of the experimental group following co-transfection of miRNA mimic and wild-type reporter gene plasmid was significantly lower compared with the other experimental groups (P<0.05), suggesting that miR-335 and miR-495 could specifically bind to the 3'-untranslated region of the ALOX5AP gene, thereby downregulating its expression. The present study provided preliminary evidence demonstrating that epigenetic regulation affects the expression of the ALOX5AP gene in patients with IS.

Predictive value of neutrophil to lymphocyte ratio and red cell distribution width on death for ST segment elevation myocardial infarction

There are many clinical scoring criteria for predicting the risk of death in patients with acute ST-segment elevation myocardial infarction (STEMI), but most of the indicators are complex to calculate and are not suitable for use in primary hospitals. Neutrophil to lymphocyte ratio (NLR) and red cell distribution width (RDW) are blood routine indicators that are easy to obtain and may help primary hospitals to evaluate the risk of death in patients with STEMI. Our aim was to explore the predictive value of NLR combined with RDW in the long-term prognosis of patients with STEMI after emergency percutaneous coronary intervention (PCI). A total of 181 patients with STEMI who underwent emergency PCI in the Affiliated Hospital of Pu-tian University from January 2017 to August 2018 were selected. Clinical profile, prognosis of all patients were collected. P value < 0.05 was considered significant. In all patients, cardiovascular death during the follow-up period was defined as cardiovascular death group, and surviving during the follow-up period was defined as survival group. There were no significant differences in demography and comorbidities between the two groups. The differences between the two groups in NLR, RDW, C-reactive protein, N-terminal-pro B type natriuretic peptide were statistically significant (P < 0.01). Binary logistic regression analysis showed that NLR (OR = 1.122, 95% CI 1.041 ~ 1.210, P = 0.003) and RDW (OR = 1.288, 95% CI 1.126 ~ 1.472, P = 0.0005) were important predictors of mortality in patients with STEMI (P < 0.05). Kaplan-Meier analysis showed that as the NLR increased, the risk of death increased (P < 0.001). In conclusion, NLR and RDW are independent predictors of cardiovascular death in patients with STEMI, and they have a certain predictive value.

Predictive efficacy of neutrophil-to-lymphocyte ratio for long-term prognosis in new onset acute coronary syndrome: a retrospective cohort study

BACKGROUND

Inflammation is involved in the pathogenesis and progression of coronary artery diseases (CADs), including acute coronary syndrome. The neutrophil-to-lymphocyte ratio (NLR) has been identified as a novel marker of the pro-inflammatory state. We aimed to evaluate the predictive efficacy of the NLR for the prognosis of patients with new-onset ACS.

METHODS

We retrospectively included consecutive patients with new-onset ACS treated with emergency coronary angiography. NLR was measured at baseline and analyzed by tertiles. The severity of coronary lesions was evaluated by the Gensini score. Correlations of NLR with the severity of CAD and the incidence of major adverse cardiovascular diseases (MACEs) during follow-up were determined.

RESULTS

Overall, 737 patients were included. The NLR was positively correlated with the severity of coronary lesions as assessed by Gensini score (P < 0.05). During the follow-up period (mean, 43.49 ± 23.97 months), 65 MACEs occurred. No significant association was detected between baseline NLR and the risk of MACEs during follow-up by either Kaplan-Meier or Cox regression analysis. Multivariable logistic regression analysis showed that a higher NLR was independently associated with coronary lesion severity as measured by the Gensini score (1st tertile vs. 3rd tertile hazard ratio [HR]: 0.527, P < 0.001, and 2nd tertile vs. 3rd tertile HR: 0.474, P = 0.025).

CONCLUSIONS

The NLR may be associated with coronary disease severity at baseline but is not associated with adverse outcomes in patients with new-onset ACS.

ETHICS APPROVAL NUMBER

2019XE0208.

Combined PET/DCE-MRI in a Rabbit Model of Atherosclerosis: Integrated Quantification of Plaque Inflammation, Permeability, and Burden During Treatment With a Leukotriene A4 Hydrolase Inhibitor

OBJECTIVES

The authors sought to develop combined positron emission tomography (PET) dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) to quantify plaque inflammation, permeability, and burden to evaluate the efficacy of a leukotriene A4 hydrolase (LTA4H) inhibitor in a rabbit model of atherosclerosis.

BACKGROUND

Multimodality PET/MRI allows combining the quantification of atherosclerotic plaque inflammation, neovascularization, permeability, and burden by combined ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET, DCE-MRI, and morphological MRI. The authors describe a novel, integrated PET-DCE/MRI protocol to noninvasively quantify these parameters in aortic plaques of a rabbit model of atherosclerosis. As proof-of-concept, the authors apply this protocol to assess the efficacy of the novel LTA4H inhibitor BI691751.

METHODS

New Zealand White male rabbits (N = 49) were imaged with integrated PET-DCE/MRI after atherosclerosis induction and 1 and 3 months after randomization into 3 groups: 1) placebo; 2) high-dose BI691751; and 3) low-dose BI691751. All animals were euthanized at the end of the study.

RESULTS

Among the several metrics that were quantified, only maximum standardized uptake value and target-to-background ratio by ¹⁸F-FDG PET showed a modest, but significant, reduction in plaque inflammation in rabbits treated with low-dose BI691751 (p = 0.03), whereas no difference was detected in the high-fat diet and in the high-dose BI691751 groups. No differences in vessel wall area by MRI and area under the curve by DCE-MRI were detected in any of the groups. No differences in neovessel and macrophage density were found at the end of study among groups.

CONCLUSIONS

The authors present a comprehensive, integrated ¹⁸F-FDG PET and DCE-MRI imaging protocol to noninvasively quantify plaque inflammation, neovasculature, permeability, and burden in a rabbit model of atherosclerosis on a simultaneous PET/MRI scanner. A modest reduction was found in plaque inflammation by ¹⁸F-FDG PET in the group treated with a low dose of the LTA4H inhibitor BI691751.

Sensitivity and Specificity of the Platelet-Lymphocyte Ratio and the Neutrophil-Lymphocyte Ratio in Diagnosing Acute Mesenteric Ischemia in Patients Operated on for the Diagnosis of Mesenteric Ischemia: A Retrospective Case-Control Study

Aim: The present study aims to determine whether various hematological parameters and ratios of patients could be used to diagnose AMI. Materials and Methods: The subjects of the study are the patients who were hospitalized with an acute mesenteric ischemia (AMI) pre-diagnosis and underwent surgery as a consequence. The patients who were determined to have the diagnosis of AMI intraoperatively are categorized in the AMI Group. The patients whose operations do not reveal AMI (negative exploration) are categorized in the Control Group. These two groups are compared in terms of hematological parameters and rates. Results: In the study, the PLR (p = 0.017), NLR (p = 0.33), PDW (0.023), RDW (p = 0.025) values are significantly higher in the AMI group compared to the control group while the LYMP (p = 0.023) count is significantly lower. Conclusions: For the patients admitted to the emergency clinics with suspected AMI, the increased PLR, NLR, PDW, and RDW values together with the reduced lymphocyte count can be used to support the diagnosis.

Role of the high-affinity leukotriene B4 receptor signaling in fibrosis after unilateral ureteral obstruction in mice

Leukotriene B₄ (LTB₄) is a lipid mediator that acts as a potent chemoattractant for inflammatory leukocytes. Kidney fibrosis is caused by migrating inflammatory cells and kidney-resident cells. Here, we examined the role of the high-affinity LTB₄ receptor BLT1 during development of kidney fibrosis induced by unilateral ureteral obstruction (UUO) in wild-type (WT) mice and BLT1 knockout (BLT1^-/-) mice. We found elevated expression of 5-lipoxygenase (5-LOX), which generates LTB₄, in the renal tubules of UUO kidneys from WT mice and BLT1^-/- mice. Accumulation of immunoreactive type I collagen in WT UUO kidneys increased over time; however, the increase was less prominent in BLT1^-/- UUO kidneys. Accumulation of S100A4-positive fibroblasts increased temporally in WT UUO kidneys, but was again less pronounced in-BLT1^-/- UUO kidneys. The same was true of mRNA encoding transforming growth factor-β (TGF)-β and fibroblast growth factor (FGF)-2. Finally, accumulation of F4/80-positive macrophages, which secrete TGF-β, increased temporally in WT UUO and BLT1^-/- UUO kidneys, but to a lesser extent in the latter. Following LTB₄ stimulation in vitro, macrophages showed increased expression of mRNA encoding TGF-β/FGF-2 and Col1a1, whereas L929 fibroblasts showed increased expression of mRNA encoding α smooth muscle actin (SMA). Bone marrow (BM) transplantation studies revealed that the area positive for type I collagen was significantly smaller in BLT1^-/—BM→WT than in WT-BM→WT. Thus, LTB₄-BLT1 signaling plays a critical role in fibrosis in UUO kidneys by increasing accumulation of macrophages and fibroblasts. Therefore, blocking BLT1 may prevent renal fibrosis.

Importance of hypersensitivity in adverse reactions to drugs in the elderly

Background

The use of drugs in the elderly is very extensive because of the frequent occurrence of chronic diseases. Adverse drug reactions (ADRs) commonly occur in geriatric patients receiving multiple therapeutic regimens. In the literature, little attention has been given to ADRs in the elderly, and particularly to allergic reactions.

Objective

The aim of the present study is to provide data on possible inappropriate prescriptions in the elderly in relation to allergic reactions and to identify a list of drugs which are likely inducers of allergic reactions.

Methods

We retrospectively evaluated ADRs in patients referring to Immunoallergy Unit of Hospital Policlinico in Bari on the basis of Beers criteria. Among adverse reactions, hypersensitivity reactions were extracted and a comparison between different age groups was assessed.

Results

Out of 823 patients with ADRs, in 30.6% hypersensitivity drug reactions (HDR) were diagnosed. Data about drug intake, comorbidities and clinical presentation were collected, aiming to identify possible risk factors. An evaluation of drugs most commonly involved was assessed.

Conclusions

HDR are reported to represent 5-10% of all ADRs, while in our study population the prevalence was about 30%. This suggests the need to develop strategies to minimize the incidence of drug allergy in the elderly, as well to reduce the phenomenon of inappropriate prescriptions.

Arachidonic acid induces macrophage cell cycle arrest through the JNK signaling pathway

Background

Arachidonic acid (AA) has potent pro-apoptotic effects on cancer cells at a low concentration and on macrophages at a very high concentration. However, the effects of AA on the macrophage cell cycle and related signaling pathways have not been fully investigated. Herein we aim to observe the effect of AA on macrophages cell cycle.

Results

AA exposure reduced the viability and number of macrophages in a dose- and time-dependent manner. The reduction in RAW264.7 cell viability was not caused by apoptosis, as indicated by caspase-3 and activated caspase-3 detection. Further research illustrated that AA exposure induced RAW264.7 cell cycle arrested at S phase, and some cell cycle-regulated proteins were altered accordingly. Moreover, JNK signaling was stimulated by AA, and the stimulation was partially reversed by a JNK signaling inhibitor in accordance with cell cycle-related factors. In addition, nuclear and total Foxo1/3a and phosphorylated Foxo1/3a were elevated by AA in a dose- and time-dependent manner, and this elevation was suppressed by the JNK signaling inhibitor.

Conclusion

Our study demonstrated that AA inhibits macrophage viability by inducing S phase cell cycle arrest. The JNK signaling pathway and the downstream FoxO transcription factors are involved in AA-induced RAW264.7 cell cycle arrest.

Electronic supplementary material

The online version of this article (10.1186/s12944-018-0673-0) contains supplementary material, which is available to authorized users.

The yin and yang of leukotriene B4 mediated inflammation in cancer

The high affinity leukotriene B₄ receptor, BLT1 mediates chemotaxis of diverse leukocyte subsets to the sites of infection or inflammation. Whereas the pathological functions of LTB₄/BLT1 axis in allergy, autoimmunity and cardiovascular disorders are well established; its role in cancer is only beginning to emerge. In this review, we summarize recent findings on LTB₄/BLT1 axis enabling distinct outcomes toward tumor progression. In a mouse lung tumor model promoted by silicosis-induced inflammation, genetic deletion of BLT1 attenuated neutrophilic inflammation and tumor promotion. In contrast, in a spontaneous model of intestinal tumorigenesis, absence of BLT1 led to defective mucosal host response, altered microbiota and bacteria dependent colon tumor progression. Furthermore, BLT1 mediated CD8⁺ T cell recruitment was shown to be essential for initiating anti-tumor immunity in number of xenograft models and is critical for effective PD1 based immunotherapy. BLT2 mediated chemotherapy resistance, tumor promotion and metastasis are also discussed. This new information points to a paradigm shift in our understanding of the LTB₄ pathways in cancer.

Global Metabolomics Reveals the Metabolic Dysfunction in Ox-LDL Induced Macrophage-Derived Foam Cells

Atherosclerosis (AS) is a chronic disorder of large arteries that is a major risk factors of high morbidity and mortality. Oxidative modification LDL is one of the important contributors to atherogenesis. Macrophages take up ox-LDL and convert into foam cells, which is the hallmark of AS. To advance the understanding of the metabolic perturbation involved in ox-LDL induced macrophage-derived foam cells and discover the potential biomarkers of early AS, a global metabolomics approach was applied based on UHPLC-QTOF/MS. Multivariate statistical analyses identified five metabolites (25-azacholesterol, anandamide, glycocholate, oleoyl ethanolamide, and 3-oxo-4, 6-choladienoate) for distinguishing foamy macrophages from controls. Among the six main metabolic pathways, the unsaturated fatty acid, especially arachidonic acid metabolism, contributed importantly to early AS. A new biomarker, anandamide (AEA), whose synthesis and metabolism in macrophages are disturbed by overloaded ox-LDL, results in metabolic obstruction. This study is the first to investigate the metabolic disturbance in macrophage-derived foam cells induced by ox-LDL and screen potential biomarkers and metabolic pathways associated with early AS. Our findings provide a new insight in the underlying pathophysiological mechanisms and also help to identify novel targets for the intervention of AS.

Consumption of Red Meat, but Not Cooking Oils High in Polyunsaturated Fat, Is Associated with Higher Arachidonic Acid Status in Singapore Chinese Adults

High arachidonic acid (AA; 20:4n-6) status may have adverse effects on inflammation and risk of cardiovascular diseases. Concerns about high intake of n-6 polyunsaturated fatty acids (PUFAs) are based on the premise that endogenous conversion from linoleic acid (LA; 18:2n-6) is an important source of AA, but few population-based studies have investigated dietary determinants of AA status. In this study, we examined habitual food consumption in relation to plasma concentrations of AA and other PUFAs in population-based studies. We used cross-sectional data from 269 healthy, ethnic Chinese participants (25–80 years old) with contrasting intakes of fish and red meat from the Singapore Prospective Study Program and 769 healthy participants (44–74 years old) from the Singapore Chinese Health Study as a validation set. Multivariable linear regression was used to examine PUFA intake (% energy) and food sources of PUFA (fish, red meat, poultry, soy and cooking oils) in relation to plasma PUFAs (AA, LA, dihomo-gamma-linolenic acid (DGLA; 20:3n-6), alpha-linolenic acid (ALA; 18:3n-3), eicosapentaenoic acid (EPA; 20:5n-3), and docosahexaenoic acid (DHA; 22:6n-3)) concentrations. Higher intake of red meat was associated with higher plasma AA concentrations. High intake of PUFA or PUFA-rich oils was associated with higher plasma ALA but not with plasma AA. Higher intakes of soy were associated with higher ALA and fish with higher DHA and EPA concentrations. These associations were statistically significant (p < 0.05) in both studies. Red meat consumption, but not PUFA or PUFA-rich cooking oil, was associated with circulating AA suggesting that intake of pre-formed AA rather than LA is an important determinant of AA status. A diet high in fish, soy products and polyunsaturated cooking oil, and low in red meat may be associated with an optimal plasma profile of PUFA in this Chinese population.

Neutrophil Lymphocyte Ratio as a Predictor of Left Ventricular Apical Thrombus in Patients with Myocardial Infarction

BACKGROUND AND OBJECTIVES

In this study, we examined the role of inflammatory parameters in an apical mural thrombus with a reduced ejection fraction due to large anterior myocardial infarction (MI).

SUBJECTS AND METHODS

A total of 103 patients who had suffered from heart failure, 45 of whom had left ventricular apical thrombus (AT) after a large anterior MI, were enrolled in the study. A detailed clinical history was taken of each participant, biochemical inflammatory markers, which were obtained during admission, were analyzed and an echocardiographical and angiographical evaluation of specific parameters were performed.

RESULTS

There were no statistically significant differences in terms of age, gender, and history of hypertension, diabetes mellitus, and atrial fibrillation between both groups (p>0.05). Similarly there were no statistically significant differences in terms of biochemical and echocardiographic parameters (p>0.05). However, there were significant differences in terms of neutrophil lymphocyte ratio (p=0.032). After a multivariate regression analysis, neutrophil lymphocyte ratio (NLR) was an independent predictor of thrombus formation (β: 0.296, p=0.024). The NLR >2.74 had a 78% sensivity and 61% specifity in predicting thrombus in patients with a low left ventricular ejection fraction.

CONCLUSION

In this study, neutrophil lymphocyte ratios were significantly higher in patients with apical thrombus.

Expression and cell distribution of leukotriene B4 receptor 1 in the rat brain cortex after experimental subarachnoid hemorrhage

Convincing evidence supports that nuclear factor kappa B (NF-κB)-meditated inflammation contributes to the adverse prognosis of aneurysmal subarachnoid hemorrhage (SAH), and pathologic neutrophil accumulation after SAH in the brain parenchyma enhances the inflammatory process. Leukotriene B4 (LTB4) is a highly potent lipid chemoattractant of neutrophils, and its biological effects are mediated primarily through the high-affinity LTB4 receptor 1 (BLT1). It is verified that NF-κB-dependent BLT1 mediates LTB4 signaling and LTB4 stimulates NF-κB-dependent inflammation via BLT1. This study aimed to determine the expression and cell distribution of BLT1 in the brain cortex after SAH and investigate the potential relationship between protein expressions of BLT1 and NF-κB. Male Sprague-Dawley rats were randomly assigned into sham group and SAH groups at 6h, 12h and on day 1, day 2 and day 3 (n=6 for each subgroup). SAH groups suffered experimental SAH by injecting 0.3ml autologous blood into the prechiasmatic cistern. BLT1 expression was measured by real-time PCR, western blot, immunohistochemistry and immunofluorescence. Nuclear expression of p65 protein, the major subunit of NF-κB, was also detected by western blot. Our data showed that the expression levels of BLT1 and nuclear p65 protein were both markedly increased after SAH. Moreover, there was a significant positive correlation between BLT1 and nuclear p65 protein expressions in the same specific time course. Double immunofluorescence staining showed that BLT1 were mainly expressed in neurons, microglia and endothelial cells rather than astrocytes after SAH. These results suggest that BLT1 may participate in the NF-κB-mediated inflammatory response after SAH, and there might be important implications for further studies using specific BLT1 antagonists to attenuate the NF-κB-mediated inflammation after SAH.

BLT1 signalling protects the liver against acetaminophen hepatotoxicity by preventing excessive accumulation of hepatic neutrophils

Leukotriene B₄ (LTB₄) is a potent chemoattractant for neutrophils. Signalling of LTB₄ receptor type 1 (BLT₁) has pro-inflammatory functions through neutrophil recruitment. In this study, we investigated whether BLT₁ signalling plays a role in acetaminophen (APAP)-induced liver injury by affecting inflammatory responses including the accumulation of hepatic neutrophils. BLT₁-knockout (BLT₁^−/−) mice and their wild-type (WT) counterparts were subjected to a single APAP overdose (300 mg/kg), and various parameters compared within 24 h after treatment. Compared with WT mice, BLT₁^−/− mice exhibited exacerbation of APAP-induced liver injury as evidenced by enhancement of alanine aminotransferase level, necrotic area, hepatic neutrophil accumulation, and expression of cytokines and chemokines. WT mice co-treated with APAP and ONO-0457, a specific antagonist for BLT₁, displayed amplification of the injury, and similar results to those observed in BLT₁^−/− mice. Hepatic neutrophils in BLT₁^−/− mice during APAP hepatotoxicity showed increases in the production of reactive oxygen species and matrix metalloproteinase-9. Administration of isolated BLT₁-deficient neutrophils into WT mice aggravated the liver injury elicited by APAP. These results demonstrate that BLT₁ signalling dampens the progression of APAP hepatotoxicity through inhibiting an excessive accumulation of activated neutrophils. The development of a specific agonist for BLT₁ could be useful for the prevention of APAP hepatotoxicity.

Relative Inhibitions of 5-Lipoxygenase and Myeloperoxidase and Free-Radical Scavenging Activities of Daidzein, Dihydrodaidzein, and Equol

The effects of bioavailability and metabolic transformation on the biological activities of daidzein are relatively unknown. The effects of daidzein, dihydrodaidzein, and equol at physiologically relevant concentrations on the production of leukotriene B4 and F2-isoprostanes, and myeloperoxidase enzyme activity in freshly isolated human neutrophils were examined. Equol, at physiological concentrations, inhibited leukotriene B4 production (IC50-200 nmol/L) in human neutrophils significantly more than daidzein and dihydrodaidzein (IC50 values >1000 nmol/L). Daidzein, dihydrodaidzein, and equol did not affect the enzymatic hydrolysis of leukotriene A4 to leukotriene B4, suggesting that they exerted their inhibitory effects on the 5-lipoxygenase activity. Daidzein (IC50 = 600 nmol/L) protected against free radical peroxidation of arachidonic acid significantly more than did equol and dihydrodaidzein (IC50 values >1000 nmol/L). Equol also showed significantly greater inhibition of myeloperoxidase activity (IC50 = 450 nmol/L) when compared to daidzein and dihydrodaidzein. Equol accumulated within the human neutrophils at significantly higher concentrations than daidzein and dihydrodaidzein after incubation with the three compounds at physiologically relevant concentrations. Neutrophils were able to accumulate intracellular daidzein, dihydrodaidzein, and equol up to a concentration of ∼600 nmol/L. Our results provide in vitro evidence that the biological activities of daidzein are profoundly influenced by bioavailability and metabolic transformation.

Regulation of cytotoxic T-Lymphocyte trafficking to tumors by chemoattractants: implications for immunotherapy

Cancer immunotherapy has recently emerged as an important treatment modality. FDA approval of provenge, ipilimumab and pembrolizumab has started to deliver on the long awaited promise of cancer immunotherapy. Many new modalities of immunotherapies targeting cytotoxic T lymphocytes (CTLs) responses, such as adoptive cell therapies and vaccines, are in advanced clinical trials. In all these immunotherapies, migration of CTLs to the tumor site is a critical step for achieving therapeutic efficacy. However, inefficient infiltration of activated CTLs into established tumors is increasingly being recognized as one of the major hurdles limiting efficacy. Mechanisms that control migration of CTLs to tumors are poorly defined. In this review, the authors discuss the chemoattractants and their receptors that have been implicated in endogenous- or immunotherapy-induced CTL recruitment to tumors and the potential for targeting these pathways for therapeutic efficacy.

Association of ALOX5AP rs10507391/SG13S114 A>T polymorphism with cerebral infarction in the Chinese population: a meta-analysis study

Various studies have investigated that the single nucleotide polymorphisms (SNPs) rs10507391/SG13S114 A>T polymorphism could increase the risk of cerebral infarction, however these results still remain controversial. Therefore we conducted a meta-analysis to estimate the association of the 5-lipoxygenase-activating protein gene (ALOX5AP) rs10507391/SG13S114 A > T polymorphism with the incidence of cerebral infarction in the Chinese population. Our researchers searched PubMed, Embase, Web of Science databases, China Biological Medicine Database (CBMD), Wanfang Chinese database, and the Chinese National Knowledge Infrastructure (CNKI) database. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were extracted and pooled to assess the strength of the association between the ALOX5AP rs10507391/SG13S114 A>T polymorphism and incidence of cerebral infarction. A total of 12 eligible studies including 6,844 cases and 7,850 controls based on the search criteria were involved in this meta-analysis. The distributions of genotypes in the cases and controls were all in agreement with Hardy-Weinberg equilibrium. We observed that the ALOX5AP rs10507391/SG13S114 A>T polymorphism carried with T allele contrast model, the homozygote codominant model, the heterozygote codominant model, the dominant model and the recessive model (all the models p > 0.05) had no risk of cerebral infarction when all studies were pooled into the meta-analysis. The results of the meta-analysis indicate that ALOX5AP rs10507391/SG13S114 A>T polymorphism is not associated with the risk of cerebral infarction in the Chinese population.

Human-specific epigenetic variation in the immunological Leukotriene B4 Receptor (LTB4R/BLT1) implicated in common inflammatory diseases

BACKGROUND

Common human diseases are caused by the complex interplay of genetic susceptibility as well as environmental factors. Due to the environment's influence on the epigenome, and therefore genome function, as well as conversely the genome's facilitative effect on the epigenome, analysis of this level of regulation may increase our knowledge of disease pathogenesis.

METHODS

In order to identify human-specific epigenetic influences, we have performed a novel genome-wide DNA methylation analysis comparing human, chimpanzee and rhesus macaque.

RESULTS

We have identified that the immunological Leukotriene B4 receptor (LTB4R, BLT1 receptor) is the most epigenetically divergent human gene in peripheral blood in comparison with other primates. This difference is due to the co-ordinated active state of human-specific hypomethylation in the promoter and human-specific increased gene body methylation. This gene is significant in innate immunity and the LTB4/LTB4R pathway is involved in the pathogenesis of the spectrum of human inflammatory diseases. This finding was confirmed by additional neutrophil-only DNA methylome and lymphoblastoid H3K4me3 chromatin comparative data. Additionally we show through functional analysis that this receptor has increased expression and a higher response to the LTB4 ligand in human versus rhesus macaque peripheral blood mononuclear cells. Genome-wide we also find human species-specific differentially methylated regions (human s-DMRs) are more prevalent in CpG island shores than within the islands themselves, and within the latter are associated with the CTCF motif.

CONCLUSIONS

This result further emphasises the exclusive nature of the human immunological system, its divergent adaptation even from very closely related primates, and the power of comparative epigenomics to identify and understand human uniqueness.

Usefulness of novel hematologic inflammatory parameters to predict prosthetic mitral valve thrombosis

Prosthetic valve thrombosis (PVT) is a life-threatening complication. Neutrophil/lymphocyte ratio (NLR) and platelet/lymphocyte ratio (PLR) have been studied as inflammatory biomarkers in atherosclerosis, but data regarding valvular disease are lacking. The study population included patients with mitral PVT (n = 152) versus control subjects (n = 164) with functional mitral prosthesis. Transesophageal echocardiography was performed to diagnose PVT. NLR and PLR were calculated using complete blood count. C-reactive protein (CRP) levels were also analyzed. Neutrophil and platelet levels did not differ between the groups (4.9 ± 2.0 vs 4.7 ± 1.5, p = 0.84 and 254.8 ± 89.7 vs 241.5 ± 62.8 p = 0.36, respectively), but lymphocyte levels were significantly lower in patients with PVT than the controls (1.8 ± 0.7 vs 2.2 ± 0.6, p <0.001). NLR, PLR, and CRP levels were significantly higher in patients with PVT than in controls (3.2 ± 2.1 vs 2.2 ± 0.8, p <0.001; 163 ± 77.5 vs 114.9 ± 37.3, p <0.001; and 1.97 ± 3.02 vs 1.02 ± 1.22, p = 0.01, respectively). A positive correlation was observed between NLR and PLR (r = 528, p <0.001). NLR level of >2.23, measured on admission, yielded an area under the curve value of 0.659 (95% confidence interval 0.582 to 0.736, sensitivity 66%, specificity 60%, p <0.001) and PLR level of >117.78 yielded an area under the curve value of 0.707 (95% confidence interval 0.636 to 0.777, sensitivity 70%, specificity 58%, p <0.001). Multivariate analysis showed that increased PLR and inadequate anticoagulation were independent predictors of thrombosis in patients with PVT. In conclusion, patients with PVT had increased NLR, PLR, and CRP levels compared with subjects with normofunctional prosthesis, and increased PLR was an independent predictor of mitral PVT.

Leukotriene haplotype × diet interaction on carotid artery hypertrophy and atherosclerosis in American Indians: the Strong Heart Family Study

OBJECTIVE

Gene × diet interaction plays an important role in atherosclerosis, an inflammatory disorder. Leukotrienes are the most potent inflammatory mediators, and genetic variants encoding leukotriene genes have been implicated in atherosclerosis. This study tests nutrigenetic interaction of a previously defined leukotriene haplotype on carotid artery hypertrophy and atherosclerosis in American Indians.

METHODS

This study included 3402 American Indians participating in the Strong Heart Family Study (SHFS). Carotid artery measurements, including intima-media thickness (IMT), vascular mass, and plaque, were assessed using ultrasound. Eleven tagSNPs in the leukotriene A4 hydrolase (LTA4H) gene were genotyped in all subjects. Main haplotype effect and haplotype × diet interaction were examined by generalized estimating equation, adjusting for known risk factors.

RESULTS

There was no significant main effect of haplotype or diet on any of the carotid artery measures. However, a previously defined LTA4H haplotype, called HapE, significantly interacted with dietary intake of n-3 and n-6 fatty acids on both IMT (P(HapE × n3) = 0.018, P(HapE × n6) = 0.040) and vascular mass (P(HapE × n3) = 0.012, P(HapE × n6) = 0.018), but not plaque. The direction of this nutrigenetic interaction on IMT was consistent with that reported in a recent study of Caucasian twins.

CONCLUSION

Dietary intake of polyunsaturated fatty acids significantly modifies the effect of a leukotriene haplotype on carotid artery hypertrophy but not atherosclerosis in American Indians, independent of established cardiovascular risk factors. Replication of nutrigenetic interaction in two distinct ethnic groups suggests the robustness and generalizability of our findings to diverse populations.

Can Admission Neutrophil to Lymphocyte Ratio Predict Infarct-Related Artery Patency in ST-Segment Elevation Myocardial Infarction

Objectives:

In this study, we aimed to investigate the relationship between neutrophil to lymphocyte ratio (NLR) and infarct-related artery (IRA) patency in patients with ST-segment elevation myocardial infarction (STEMI).

Methods:

A total of 349 patients with STEMI were recruited to this retrospective study. Baseline characteristics were reviewed. Patency of IRA was evaluated by thrombolysis in myocardial infarction flow grade.

Results:

Of all patients, 293 patients formed the occluded IRA group and 56 patients formed the patent IRA group. The NLR was significantly higher in occluded IRA group (4.4 ± 4.1 vs 1.9 ± 1.1, P < .001). Glucose levels were also higher in occluded IRA group (171.3 ± 78.0 vs 144.7 ± 49.7, P = .022). Regression analysis demonstrated admission NLR and plasma glucose levels as independent predictors of IRA patency.

Conclusion:

In this study, we found that admission NLR and glucose levels were higher in patients with occluded IRA than in patients with STEMI. We also found that NLR and glucose levels were independent predictors of IRA patency. Because hemogram is a cheap, fast, and widely available test, it can be used in daily practice as a predictor of IRA patency.

Leukotriene B4 type-1 receptor signaling promotes liver repair after hepatic ischemia/reperfusion injury through the enhancement of macrophage recruitment

Recruited macrophages play a critical role in liver repair after acute liver injury. Leukotriene B4 (LTB4) is a potent chemoattractant for macrophages. In this study, we investigated the role of LTB4 receptor type 1 (BLT1) in liver repair during hepatic ischemia/reperfusion (I/R) injury. BLT1-knockout mice (BLT1(-/-)) or their wild-type counterparts (WT) were subjected to partial hepatic I/R. Compared with WT, BLT1(-/-) exhibited delayed liver repair and hepatocyte proliferation accompanied by a 70% reduction in the recruitment of macrophages and a 70-80% attenuation in hepatic expression of epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), and VEGF receptor 1 (VEGFR1). Disruption of BLT1 signaling also reduced the expression of EGF by 67% on recruited macrophages expressing VEGFR1 in the injured liver. Treatment of WT mice with an EGF-neutralizing antibody delayed liver repair and reduced macrophage recruitment, compared with control immunoglobulin G (IgG). BLT1 signaling enhanced the expression of VEGF, VEGFR1, and EGF in isolated peritoneal macrophages in vitro. These results indicate that BLT1 signaling plays a role in liver repair after hepatic I/R through enhanced expression of EGF in recruited macrophages and that the development of a specific agonist for BLT1 could be useful for liver recovery from acute liver injury.

The neutrophil to lymphocyte ratio was associated with impaired myocardial perfusion and long term adverse outcome in patients with ST-elevated myocardial infarction undergoing primary coronary intervention

OBJECTIVES

In the present study we aimed to reveal any probable correlation between neutrophil-to-lymphocyte ratio (N/L ratio) and the occurrence of no-reflow, along with assessment of the prognostic value of N/L ratio in patients with ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

The N/L ratio stands practically for the balance between neutrophil and lymphocyte counts in the body, which can also be utilized as an index for systemic inflammatory status.

METHODS

In our study, we included 204 consecutive patients suffering from STEMI who underwent primary percutaneous coronary intervention (PCI). Patients with STEMI were assigned into distinct tertiles based on their N/L ratios on admission. No-reflow encountered following PCI was evaluated through both angiography [Thrombolysis in Myocardial Infarction (TIMI) flow and myocardial blush grade (MBG)] and electrocardiography (as ST-segment resolution).

RESULTS

Patients featured with no ST-resolution were documented to have displayed significantly higher N/L ratio on admission compared to those with intermediate or complete ST-segment resolution. The number of the patients characterized with no-reflow, evident both angiographically (TIMI flow ≤ 2 or TIMI flow 3 with final myocardial bush grade ≤ 2 after PCI) and electrocardiographically (ST-resolution <30%), was encountered to depict increments throughout successive N/L ratio tertiles. Moreover, the same also held true for three-year mortality rates across the tertile groups (9% vs. 15% vs. 35%, p < 0.01). Multivariable logistic regression analysis disclosed that N/L ratio on admission stood for a significant indicator for long-term mortality in patients with no-reflow phenomenon detected with MBG. Elevated N/L ratio on admission was also found to be a significant indicator for three-year mortality and major adverse cardiac events.

CONCLUSIONS

In patients with STEMI who underwent primary PCI, elevated N/L ratios on admission were revealed to be correlated with both no-reflow phenomenon and long-term prognosis.

Leukotriene A4 hydrolase haplotype, diet and atherosclerosis: a twin study

OBJECTIVE

Atherosclerosis is an inflammatory process resulting from the interaction between genetic and environmental factors. Leukotrienes are inflammatory mediators generated from arachidonic acid, and genetic polymorphisms involved in leukotriene metabolism are implicated in atherosclerosis. The objectives of this study are to examine whether genetic variants in key leukotriene enzymes are associated with atherosclerosis, and whether dietary intake of competing leukotriene substrates modifies the effect of leukotriene variants on atherosclerosis.

METHODS

Atherosclerosis was assessed by common carotid intima-media thickness (IMT) using ultrasound. Sequence variants within arachidonate 5-lipoxygenase activating protein (ALOX5AP) and leukotriene A4 hydrolase (LTA4H) genes were analyzed with 32 single nucleotide polymorphisms (SNPs) in 169 Caucasian twin pairs from the Vietnam Era Twin Registry. The associations between genetic polymorphisms and carotid atherosclerosis, and gene × diet interactions were examined by generalized estimating equation controlling for potential confounders.

RESULTS

A six-SNP haplotype in LTA4H, designated HapE, was significantly associated with carotid IMT after adjusting for known coronary risk factors. Twins carrying HapE had a much lower IMT compared to twins not carrying (695 μm vs. 750 μm, p = 0.0007). Moreover, dietary intake of polyunsaturated fatty acids strongly augmented the cardioprotective effect of HapE among those with this haplotype but not those without, suggesting a haplotype × diet interaction (interaction P(HapE×n-3) = 0.03, P(HapE×n-6) = 0.015).

CONCLUSION

We identified a novel leukotriene haplotype that appears to be protective toward subclinical atherosclerosis. This association is modified by dietary intake of polyunsaturated fatty acids.

Prognostic value of neutrophil/lymphocyte ratio in patients with ST-elevated myocardial infarction undergoing primary coronary intervention: a prospective, multicenter study

OBJECTIVE

The pre-procedural neutrophil to lymphocyte ratio (N/L) is associated with adverse outcomes among patients with coronary artery disease but its prognostic value in ST-segment elevation myocardial infarction (STEMI) has not been fully investigated. This study evaluated the relations between pre-procedural N/L ratio and the in-hospital and long-term outcomes in STEMI patients undergoing primary percutaneous coronary intervention (PCI).

METHODS

A total of 682 STEMI patients presented within the first 6h of symptom onset were enrolled and stratified according to tertiles of N/L ratio based on the blood samples obtained in the emergency room upon admission.

RESULTS

The mean follow-up period was 43.3 months (1-131 months). In-hospital in-stent thrombosis, non-fatal myocardial infarction, and cardiovascular mortality increased as the N/L tertile ratio increased (p<0.001, p<0.001, p=0.003, respectively). Long-term in-stent thrombosis, non-fatal myocardial infarction and cardiovascular mortality also increased as the N/L ratio increased (p<0.001, p<0.001, p=0.002, respectively). On multivariate analysis, N/L ratio remained an independent predictor for both in-hospital (OR 1.189, 95% CI 1.000-1.339; p<0.001) and long-term major (OR 1.228, 95% CI 1.136-1.328; p<0.001) adverse cardiac events.

CONCLUSION

The N/L ratio was an independent predictor of both in-hospital and long-term adverse outcomes among STEMI patients undergoing primary PCI. Our findings suggest that this inexpensive, universally available hematological marker may be incorporated into the current established risk assessment model for STEMI.

Lipoxygenase and Cyclooxygenase Pathways and Colorectal Cancer Prevention

Colorectal cancer is one of the commonest malignancies in both men and women. In spite of significant progress in screening and in surgical and therapeutic interventions, colorectal cancer (CRC) is still a major public health problem. Accumulating evidence suggests that targeting inflammatory pathways may provide protection against the development of CRC. Eicosanoids derived from the enzymes cyclooxygenase (COX) and lipoxygenase (LOX) may contribute to CRC carcinogenesis. Approaches for targeting COX-1 and COX-2 with traditional nonsteroidal anti-inflammatory agents or targeting COX-2 with specific inhibitors are highly successful at the preclinical and clinical levels; however, large-scale clinical applicability of these agents is limited owing to unwanted side effects. Emerging studies suggests that 5-LOX-derived leukotrienes may contribute to colon tumor development and risk of thrombotic events. Thus, developing drugs that target both 5-LOX and COX-2 may provide a safer strategy. In this review, we discuss evidence for the involvement of 5-LOX in colon tumor development and targeting 5-LOX and COX-2 with synthetic and naturally occurring agents for CRC prevention.

Leukotriene A4 Hydrolase: Biology, Inhibitors and Clinical Applications

Leukotriene A4 hydrolase is a zinc-containing cytosolic enzyme with both hydrolase and aminopeptidase activity. LTA4H stereospecifically catalyzes the transformation of the unstable epoxide LTA4 to the potent pro-inflammatory mediator LTB4. Variations in the lta4h gene have been linked to susceptibility to multiple diseases including myocardial infarction, stroke and asthma. Pre-clinical animal models and human biomarker data have implicated LTB4 in inflammatory diseases. Several groups have now identified selective inhibitors of LTA4H, many of which were influenced by the disclosure of a protein crystal structure a decade ago. Clinical validation of LTA4H remains elusive despite the progression of inhibitors into pre-clinical and clinical development.

Real-time imaging of leukotriene B₄ mediated cell migration and BLT1 interactions with β-arrestin

G-protein coupled receptors (GPCRs) belong to the seven transmembrane protein family and mediate the transduction of extracellular signals to intracellular responses. GPCRs control diverse biological functions such as chemotaxis, intracellular calcium release, gene regulation in a ligand dependent manner via heterotrimeric G-proteins(1-2). Ligand binding induces a series of conformational changes leading to activation of heterotrimeric G-proteins that modulate levels of second messengers such as cyclic adenosine monophosphate (cAMP), inositol triphosphate (IP3) and diacyl glycerol (DG). Concomitant with activation of the receptor ligand binding also initiates a series of events to attenuate the receptor signaling via desensitization, sequestration and/or internalization. The desensitization process of GPCRs occurs via receptor phosphorylation by G-protein receptor kinases (GRKs) and subsequent binding of β-arrestins(3). β-arrestins are cytosolic proteins and translocate to membrane upon GPCR activation, binding to phosphorylated receptors (most cases) there by facilitating receptor internalization (4-6). Leukotriene B(4;) (LTB(4;)) is a pro-inflammatory lipid molecule derived from arachidonic acid pathway and mediates its actions via GPCRs, LTB(4;) receptor 1 (BLT1; a high affinity receptor) and LTB(4;) receptor 2 (BLT2; a low affinity receptor)(7-9). The LTB(4;)-BLT1 pathway has been shown to be critical in several inflammatory diseases including, asthma, arthritis and atherosclerosis(10-17). The current paper describes the methodologies developed to monitor LTB(4;)-induced leukocyte migration and the interactions of BLT1 with β-arrestin and , receptor translocation in live cells using microscopy imaging techniques(18-19). Bone marrow derived dendritic cells from C57BL/6 mice were isolated and cultured as previously described (20-21). These cells were tested in live cell imaging methods to demonstrate LTB(4;) induced cell migration. The human BLT1 was tagged with red fluorescent protein (BLT1-RFP) at C-terminus and β-arrestin1 tagged with green fluorescent protein (β-arr-GFP) and transfected the both plasmids into Rat Basophilic Leukomia (RBL-2H3) cell lines(18-19). The kinetics of interaction between these proteins and localization were monitored using live cell video microscopy. The methodologies in the current paper describe the use of microscopic techniques to investigate the functional responses of G-protein coupled receptors in live cells. The current paper also describes the use of Metamorph software to quantify the fluorescence intensities to determine the kinetics of receptor and cytosolic protein interactions.

A tagging SNP in ALOX5AP and risk of stroke: a haplotype-based analysis among eastern Chinese Han population

A genome-wide approach found significant association of two at-risk haplotypes (HapA, HapB) in the ALOX5AP gene with myocardial infarction and stroke. To date, it is still controversial whether ALOX5AP gene polymorphisms are risk factors for stroke. The aim of the present study is to investigate the association between the ALOX5AP gene polymorphism and the risk for stroke in Eastern Chinese Han population with a haplotype-based analysis. We conducted a comprehensive association study of 507 stroke patients and 510 healthy controls to assess the association between the ALOX5AP tagging single-nucleotide polymorphisms (tSNPs) and stroke risk. Genotyping was performed using the PCR-RFLP assay. In the single-locus analysis, we found that the rs9579646 AG genotype was associated with a marginally decreased risk for stroke (adjusted odds ratio, 0.65; 95% confidence interval, 0.45-0.96), compared with the AA genotype. Haplotype-based association analysis of block 2 involving rs10507391 and rs12429692 revealed that the decreased risk of stroke was significantly associated with haplotype AA (OR, 0.66; 95% CI, 0.46-0.95). These results suggested that the genetic variants in ALOX5AP might modulate the risk of stroke in Eastern Chinese Han population. The frequencies of single-marker alleles and haplotypes showed remarkable differences from those in other populations.

Relation between common allergic symptoms and coronary heart disease among NHANES III participants

We investigated whether there is an increased risk of coronary heart diseases (CHD) in those with common allergic symptoms using the NHANES III, which is a representative sample of the United States population in 1988 to 1994. CHD was defined by Rose questionnaire and history of heart attack. Allergic symptoms were categorized into no symptoms (NO), rhinoconjunctivitis without wheezing (RC), and wheezing (WZ) based on symptoms. Multivariate logistic regression was used to obtain odds ratios (ORs) of CHD. Eight thousand six hundred fifty-three nonpregnant subjects ≥20 years old with overnight fasting ≥8 hours were included. CHD was present in 5.9% of the population; 36.5% did not have allergic symptoms (NO), 45.9% had RC, and 17.6% had WZ. The prevalence of CHD was 3.9% in NO, 4.8% in RC, and 12.8% in WZ (p <0.001). Compared to NO, unadjusted ORs of CHD were 1.24 (95% confidence interval 0.94 to 1.62) in RC and 3.58 (2.68 to 4.78) in WZ and ORs adjusted for sociodemographic factors and co-morbidities were 1.40 (1.02 to 1.92) in RC and 2.64 (1.79 to 3.90) in WZ. Only the group of women <50 years of age had significantly increased ORs in RC and WZ. In conclusion, common allergic symptoms were significantly associated with an increased risk of CHD.

Specific Dietary Polyphenols Attenuate Atherosclerosis in Apolipoprotein E–Knockout Mice by Alleviating Inflammation and Endothelial Dysfunction

Objective— Animal and clinical studies have suggested that polyphenols in fruits, red wine, and tea may delay the development of atherosclerosis through their antioxidant and anti-inflammatory properties. We investigated whether individual dietary polyphenols representing different polyphenolic classes, namely quercetin (flavonol), (−)-epicatechin (flavan-3-ol), theaflavin (dimeric catechin), sesamin (lignan), or chlorogenic acid (phenolic acid), reduce atherosclerotic lesion formation in the apolipoprotein E (ApoE) −/− gene–knockout mouse.

Methods and Results— Quercetin and theaflavin (64-mg/kg body mass daily) significantly attenuated atherosclerotic lesion size in the aortic sinus and thoracic aorta ( P <0.05 versus ApoE −/− control mice). Quercetin significantly reduced aortic F 2 -isoprostane, vascular superoxide, vascular leukotriene B 4 , and plasma-sP-selectin concentrations; and augmented vascular endothelial NO synthase activity, heme oxygenase-1 protein, and urinary nitrate excretion ( P <0.05 versus control ApoE −/− mice). Theaflavin showed similar, although less extensive, significant effects. Although (−)-epicatechin significantly reduced F 2 -isoprostane, superoxide, and endothelin-1 production ( P <0.05 versus control ApoE −/− mice), it had no significant effect on lesion size. Sesamin and chlorogenic acid treatments exerted no significant effects. Quercetin, but not (−)-epicatechin, significantly increased the expression of heme oxygenase-1 protein in lesions versus ApoE −/− controls.

Conclusion— Specific dietary polyphenols, in particular quercetin and theaflavin, may attenuate atherosclerosis in ApoE −/− gene–knockout mice by alleviating inflammation, improving NO bioavailability, and inducing heme oxygenase-1. These data suggest that the cardiovascular protection associated with diets rich in fruits, vegetables, and some beverages may in part be the result of flavonoids, such as quercetin.

The LTB4-BLT1 axis mediates neutrophil infiltration and secondary injury in experimental spinal cord injury

Traumatic injury in the central nervous system induces inflammation; however, the role of this inflammation is controversial. Precise analysis of the inflammatory cells is important to gain a better understanding of the inflammatory machinery in response to neural injury. Here, we demonstrated that leukotriene B4 plays a significant role in mediating leukocyte infiltration after spinal cord injury. Using flow cytometry, we revealed that neutrophil and monocyte/macrophage infiltration peaked 12 hours after injury and was significantly suppressed in leukotriene B4 receptor 1 knockout mice. Similar findings were observed in mice treated with a leukotriene B4 receptor antagonist. Further, by isolating each inflammatory cell subset with a cell sorter, and performing quantitative reverse transcription-PCR, we demonstrated the individual contributions of more highly expressed subsets, ie, interleukins 6 and 1beta, tumor necrosis factor-alpha, and FasL, to the inflammatory reaction and neural apoptosis. Inhibition of leukotriene B4 suppressed leukocyte infiltration after injury, thereby attenuating the inflammatory reaction, sparing the white matter, and reducing neural apoptosis, as well as inducing better functional recovery. These findings are the first to demonstrate that leukotriene B4 is involved in the pathogenesis of spinal cord injury through the amplification of leukocyte infiltration, and provide a potential therapeutic strategy for traumatic spinal cord injury.

Sex-specific association of depression and a haplotype in leukotriene A4 hydrolase gene

OBJECTIVE

To assess whether genetic variants involved in inflammation play a role in the sex difference in depression. Depression is, in part, genetically determined and inflammation has been implicated. Women are twice as likely to develop depression as men.

METHODS

We examined the association, separately in men and women, between seven single nucleotide polymorphisms (SNPs) in the arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene and 12 SNPs in the leukotriene A4 hydrolase (LTA4H) gene and depression in 1368 white subjects (30.4% female) referred for cardiovascular evaluation. Depression was defined as a score of >or=10 in the Patient Health Questionnaire 9. Single marker analysis was assessed by the chi(2) test. Haplotype-specific associations were performed, using likelihood ratio tests. Empirical significance levels were determined by permutation tests.

RESULTS

Depressed individuals, comprising 14.5% of the total, were more likely to be female, current smokers, have a history of diabetes and myocardial infarction. None of the SNPs in the ALOX5AP gene, either singly or in combination, was associated with depression. The 12 SNPs in the LTA4H gene were not individually associated with depression. However, a six-SNP haplotype in LTA4H gene, named HapE, showed a significant protective effect on depression in women, but not in men, after correcting for cardiovascular effects. The interaction between HapE and sex on depression was statistically significant.

CONCLUSION

This study provides the first evidence for a sex-specific association of a novel haplotype in the LTA4H gene on depression. Although replication is needed, our study suggests that genetic variations may underlie sex differences in depression.

Polymorphism of SG13S114T/A in the ALOX5AP gene and the risk for stroke in a large Chinese cohort

The 5-lipoxygenase activating protein, an important regulator in the biosynthesis of proinflammatory leukotrienes, has been reported to confer risks for cardiovascular diseases and stroke. The purpose of this study is to assess whether genetic variants in the ALOX5AP encoding the 5-lipoxygenase activating protein will influence the risk for stroke in the Chinese population. A total of 1,773 patients with stroke and 1,713 controls were recruited from seven clinical centers. Polymorphisms of SG13S114T/A and SG13S89G/A in the ALOX5AP were genotyped by the polymerase chain reaction and the restriction enzyme analysis. The multivariate logistic regression model was used to exclude the influence of the conventional vascular risk factors on stroke. The frequency of SG13S114A allele in the ALOX5AP was significantly higher in male patients with thrombotic stroke (33.6%) than in controls (29.2%; P=0.014). The SG13S114AA genotype was significantly associated with a 1.62-fold risk for thrombotic stroke in men (95% confidence interval, 1.11 to 2.35; P=0.012). The SG13S89G/A variant was not associated with stroke or its subtypes. Haplotype analysis showed no significant differences between stroke patients and controls. The present study suggested that a common genetic variant SG13S114T/A in the ALOX5AP gene is associated with an increased risk for atherothrombotic stroke in Chinese males, and racial differences in allele and genotype frequencies may account partially for the different association findings between populations.

ATP-induced apoptosis involves a Ca2+-independent phospholipase A2 and 5-lipoxygenase in macrophages

Macrophages express P2X(7) and other nucleotide (P2) receptors, and display the phenomena of extracellular ATP (ATP(e))-induced P2X(7)-dependent membrane permeabilization and cell death by apoptosis and necrosis. P2X(7) receptors also cooperate with toll-like receptors (TLRs) to induce inflammasome activation and IL-1beta secretion. We investigated signaling pathways involved in the induction of cell death by ATP(e) in intraperitoneal murine macrophages. Apoptosis (hypodiploid nuclei) and necrosis (LDH release) were detected 6h after an induction period of 20 min in the presence of ATP. Apoptosis was blocked by caspase 3 and caspase 9 inhibitors and by cyclosporin A. The MAPK inhibitors PD-98059, SB-203580 and SB-202190 provoked no significant effect on apoptosis, but SB-203580 blocked LDH release. Neither apoptosis nor necrosis was inhibited when both intra- and extracellular Ca(2+) were chelated during the induction period. Mepacrine, a generic PLA(2) inhibitor and BEL, an inhibitor of Ca(2+)-independent PLA(2) (iPLA(2)) blocked apoptosis, while pBPB and AACOOPF(3), inhibitors of secretory and Ca(2+)-dependent PLA(2) respectively, had no significant effect. Cycloxygenase inhibitors had no effect on apoptosis, while the inhibitors of lipoxygenase (LOX) and leukotriene biosynthesis nordihydroguaiaretic acid (NDGA), zileuton, AA-861, and MK-886 significantly decreased apoptosis. Neither NDGA nor MK-886 blocked apoptosis of 5-LOX(-/-) macrophages. CP-105696 and MK-571, antagonists of leukotriene receptors, had no significant effect on apoptosis. None of the inhibitors of PLA(2) and LOX/leukotriene pathway had a significant inhibitory effect on LDH release. Our results indicate that a Ca(2+)-independent step involving an iPLA(2) and 5-LOX are involved in the triggering of apoptosis but not necrosis by P2X(7) in macrophages.

A macrophage cell model for selective metalloproteinase inhibitor design

The desire to inhibit zinc-dependent matrix metalloproteinases (MMPs) has, over the course of the last 30 years, led to the development of a plethora of MMP inhibitors that bind directly to the active-site metal. With one exception, all of these drugs have failed in clinical trials, due to many factors, including an apparent lack of specificity for MMPs. To address the question of whether these inhibitors are selective for MMPs in a biological setting, a cell-based screening method is presented to compare the relative activities of zinc, heme iron, and non-heme iron enzymes in the presence of these compounds using the RAW264.7 macrophage cell line. We screened nine different zinc-binding groups (ZBGs), four established MMP inhibitors (MMPis), and two novel MMP inhibitors developed in our laboratory to determine their selectivities against five different metalloenzymes. Using this model, we identified two nitrogen donor compounds--2,2'-dipyridylamine (DPA) and triazacyclononane (TACN)--as the most selective ZBGs for zinc metalloenzyme inhibitor development. We also demonstrated that the model could predict known nonspecific interactions of some of the most commonly used MMPis, and could also give cross-reactivity information for newly developed MMPis. This work demonstrates the utility of cell-based assays in both the design and the screening of novel metalloenzyme inhibitors.

Identification of a potent, selective, and orally active leukotriene a4 hydrolase inhibitor with anti-inflammatory activity

LTA 4H is a ubiquitously distributed 69 kDa zinc-containing cytosolic enzyme with both hydrolase and aminopeptidase activity. As a hydrolase, LTA 4H stereospecifically catalyzes the transformation of the unstable epoxide LTA 4 to the diol LTB 4, a potent chemoattractant and activator of neutrophils and a chemoattractant of eosinophils, macrophages, mast cells, and T cells. Inhibiting the formation of LTB 4 is expected to be beneficial in the treatment of inflammatory diseases such as inflammatory bowel disease (IBD), asthma, and atherosclerosis. We developed a pharmacophore model using a known inhibitor manually docked into the active site of LTA 4H to identify a subset of compounds for screening. From this work we identified a series of benzoxazole, benzthiazole, and benzimidazole inhibitors. SAR studies resulted in the identification of several potent inhibitors with an appropriate cross-reactivity profile and excellent PK/PD properties. Our efforts focused on further profiling JNJ 27265732, which showed encouraging efficacy in a disease model relevant to IBD.

12(S)-Hydroxyheptadeca-5Z, 8E, 10E-trienoic acid is a natural ligand for leukotriene B4 receptor 2

Activated blood platelets and macrophages metabolize prostaglandin H₂ into thromboxane A₂ and 12(S)-hydroxyheptadeca-5Z, 8E, 10E–trienoic acid (12-HHT) in an equimolar ratio through the action of thromboxane synthase. Although it has been shown that 12-HHT is abundant in tissues and bodily fluids, this compound has long been viewed as a by-product lacking any specific function. We show that 12-HHT is a natural ligand for leukotriene B₄ (LTB₄) receptor-2 (BLT2), a G protein–coupled receptor that was originally identified as a low-affinity receptor for LTB₄. BLT2 agonistic activity in lipid fractions from rat small intestine was identified as 12-HHT using high-performance liquid chromatography and mass spectrometry. Exogenously expressed BLT2 in mammalian cells was activated by synthetic 12-HHT, as assessed by guanosine 5′-O-(3-thio) triphosphate binding, the activation of intracellular signaling pathways, and chemotaxis assay. Displacement analysis using [³H]LTB₄ showed that 12-HHT binds to BLT2 with a higher affinity than LTB₄. Lipid extracts from cyclooxygenase 1–deficient mice failed to activate BLT2. Bone marrow–derived mast cells (BMMCs) isolated from wild-type mice migrated toward a low concentration of 12-HHT, whereas BMMCs from BLT2-deficient mice did not. We conclude that 12-HHT is a natural lipid agonist of BLT2 in vivo and induces chemotaxis of mast cells.