BACKGROUNDLeukotrienes are arachidonic acid derivatives long known for their inflammatory properties. Leukotriene-based inflammation has been demonstrated to play a crucial role in atherosclerosis, a major risk factor for several human diseases. Recently, human genetic studies from us and others suggest that single nucleotide polymorphisms (SNPs) in leukotriene pathway genes influence the risk of atherosclerotic diseases such as stroke. This study aimed to assess the role of additional leukotriene pathway genes as a stroke risk factor within the Chinese Han population.

METHODSWe sequenced the promoter, exonic, and intronic regions of leukotriene A4 hydrolase (LTA4H) and arachidonate 5-lipoxygenase (ALOX5), and then genotyped five SNPs in LTA4H and four SNPs in ALOX5 among 691 cases with stroke and 732 controls from the Chinese population.

RESULTSWe detected a significant association between an intronic SNP in LTA4H (rs6538697) and stroke in our subjects (adjusted odds ratio, recessive model, 1.75; P = 0.022); and the SNP rs2029253 in ALOX5 was associated with a decreased risk of stroke (adjusted odds ratio, 0.76; 95% confidence interval, 0.59 - 0.97).

CONCLUSIONGenetic variants in LTA4H and ALOX5 may modulate the risk of stroke in the Chinese Han population.

Aged ; Asian Continental Ancestry Group ; genetics ; Case-Control Studies ; Female ; Humans ; Leukotrienes ; biosynthesis ; Logistic Models ; Male ; Middle Aged ; Polymorphism, Single Nucleotide ; Risk ; Stroke ; etiology ; genetics

The inhibitory effect of cromakalim on the mediator release from mast cells caused by antigenantibody reactions was in controversy with the specific antigen used. However, it has recently been observed that cromakalim inhibits the release of mediators from superfused tracheal and parenchymal strips or lung mast cells after passive sensitization with the IgG1 antibody. An attempt, therefore, was made to determine the inhibitory mechanisms of cromakalim on the release of mediators such as histamine and leukotriene released by the activation of enzymes during mast cell activation. Guinea pig lung mast cells were purified through enzyme digestion, rough percoll and continuous percoll density gradients. The purified mast cells were prelabeled with [3H]palmitic acid. PLD activity was assessed more directly by the production of labeled phosphatidylethanol by PLD-mediated transphosphatidylation in the presence of ethanol. In the cells labelled with [3H]myristic acid, [3H] DAG production was measured. The methyltransferase activity was assessed by measuring the incorporation of [3H]methyl moiety into phospholipids in sensitized mast cells labelled with L-[3H] methylmethionine. cAMP level was measured by radioimmunoassay. Cromakalim resulted in a decrease in the amount of histamine and leukotrienes releases by 30% in the ovalumin-induced mast cell. Cromakalim had little effect on phospholipase D activity enhanced by the activated mast cell. Cromakalim inhibited the initial increase of diacylglycerol production during mast cell activations. Cromakalim inhibited the phospholipid methylation increased in the activated mast cell. These results show that cromakalim decreases histamine release by inhibiting the initial increase of 1,2-diacylglycerol during the mast cell activation, which is mediated via the phosphatidylinositide-phospholipase C system rather than the phosphatidylcholine-phospholipase D system. Furthermore, cromakalim reduces phosphatidylcholine production by inhibiting the methyltransferase, which decreases the conversion of phosphatidylcholine into arachidonic acid and inhibits the production of leukotrienes.
Adenylate Cyclase/metabolism ; Animal ; *Antigen-Antibody Reactions ; Benzopyrans/*pharmacology ; Cromakalim ; Diglycerides/biosynthesis ; Female ; Guinea Pigs ; Histamine Release/*drug effects ; Leukotrienes/*secretion ; Lung/drug effects/secretion ; Mast Cells/*drug effects/secretion ; Methylation ; Phospholipase D/metabolism ; Phospholipids/metabolism ; Potassium Channels/*drug effects ; Pyrroles/*pharmacology ; Support, Non-U.S. Gov't

The inhibitory effect of cromakalim on the mediator release from mast cells caused by antigenantibody reactions was in controversy with the specific antigen used. However, it has recently been observed that cromakalim inhibits the release of mediators from superfused tracheal and parenchymal strips or lung mast cells after passive sensitization with the IgG1 antibody. An attempt, therefore, was made to determine the inhibitory mechanisms of cromakalim on the release of mediators such as histamine and leukotriene released by the activation of enzymes during mast cell activation. Guinea pig lung mast cells were purified through enzyme digestion, rough percoll and continuous percoll density gradients. The purified mast cells were prelabeled with [3H]palmitic acid. PLD activity was assessed more directly by the production of labeled phosphatidylethanol by PLD-mediated transphosphatidylation in the presence of ethanol. In the cells labelled with [3H]myristic acid, [3H] DAG production was measured. The methyltransferase activity was assessed by measuring the incorporation of [3H]methyl moiety into phospholipids in sensitized mast cells labelled with L-[3H] methylmethionine. cAMP level was measured by radioimmunoassay. Cromakalim resulted in a decrease in the amount of histamine and leukotrienes releases by 30% in the ovalumin-induced mast cell. Cromakalim had little effect on phospholipase D activity enhanced by the activated mast cell. Cromakalim inhibited the initial increase of diacylglycerol production during mast cell activations. Cromakalim inhibited the phospholipid methylation increased in the activated mast cell. These results show that cromakalim decreases histamine release by inhibiting the initial increase of 1,2-diacylglycerol during the mast cell activation, which is mediated via the phosphatidylinositide-phospholipase C system rather than the phosphatidylcholine-phospholipase D system. Furthermore, cromakalim reduces phosphatidylcholine production by inhibiting the methyltransferase, which decreases the conversion of phosphatidylcholine into arachidonic acid and inhibits the production of leukotrienes.
Adenylate Cyclase/metabolism ; Animal ; *Antigen-Antibody Reactions ; Benzopyrans/*pharmacology ; Cromakalim ; Diglycerides/biosynthesis ; Female ; Guinea Pigs ; Histamine Release/*drug effects ; Leukotrienes/*secretion ; Lung/drug effects/secretion ; Mast Cells/*drug effects/secretion ; Methylation ; Phospholipase D/metabolism ; Phospholipids/metabolism ; Potassium Channels/*drug effects ; Pyrroles/*pharmacology ; Support, Non-U.S. Gov't

The pathogenesis of aspirin (acetylsalicylic acid, ASA)-intolerant urticaria (AIU) is still poorly understood but it has recently been suggested that it is associated with the overproduction of leukotriene (LT). This is supported by evidence that cyclooxygenase 2 inhibitor is given safely to patients with AIU. The present study was designed to investigate the role of genetic polymorphism of LT related genes in the pathogenesis of AIU via a case-control study. We screened single nucleotide polymorphisms (SNPs) in genes encoding enzymes involved in leukotriene synthesis in the Korean population with AIU (n=101), ASA-intolerant asthma (AIA, n=95) and normal healthy controls (n=123). Genotype was determined by primer extension reactions using the SNapShot ddNTP primer extension kit. Among 8 SNPs of four LT related genes, the polymorphism of ALOX5 at positions of -1708 G>A showed significant difference in genotype frequency between AIU and AIA (p=0.01). Furthermore, there were significant differences observed in the frequencies of two ALOX5 haplotypes between the AIU group and AIA group (p<0.05). However, there were no differences in allele, genotype, or haplotype frequencies of ALOX5 between the AIU group and the normal control group. These results suggested that ALOX5 has a differing contribution in two major clinical pathogenesis related to ASA-sensitivity.
Adult ; Arachidonate 5-Lipoxygenase/*genetics ; Aspirin/*adverse effects ; Asthma/etiology/*genetics/metabolism ; Carrier Proteins/genetics ; Case-Control Studies ; Cyclooxygenase 2/genetics ; Female ; Gene Frequency ; Genotype ; Glutathione Transferase/genetics ; Humans ; Leukotrienes/*biosynthesis ; Male ; Membrane Proteins/genetics ; Middle Aged ; Polymorphism, Single Nucleotide ; Research Support, Non-U.S. Gov't ; Urticaria/etiology/*genetics/metabolism

Acetates ; administration & dosage ; therapeutic use ; Asthma ; drug therapy ; etiology ; metabolism ; Bronchiolitis, Viral ; drug therapy ; Cysteine ; metabolism ; Humans ; Infant ; Infant, Newborn ; Leukotriene Antagonists ; administration & dosage ; therapeutic use ; Leukotrienes ; biosynthesis ; Nasopharynx ; secretion ; Quinolines ; administration & dosage ; therapeutic use ; Respiratory Syncytial Virus Infections ; drug therapy ; metabolism ; virology ; Risk Factors

Airway structural changes that occur in patients with asthma in response to persistent inflammation are termed airway remodeling. The cysteinyl leukotrienes (LTC4, D4 and E4) are known to play important roles in the pathobiology of asthma. To evaluate the effect of low dose montelukast (MK) on the development of airway remodeling using a chronic murine model of allergic airway inflammation with subepithelial fibrosis, BALB/c mice, after intraperitoneal ovalbumin (OVA) sensitization on days 0 and 14, received intranasal OVA periodically on days 14-75. MK treated mice received montelukast sodium intraperitoneally on days 26-75. The OVA sensitized/challenged mice developed an extensive eosinophil cell inflammatory response, goblet cell hyperplasia, mucus occlusion, and smooth muscle hypertrophy of the airways. In addition, in OVA sensitized/challenged mice, dense collagen deposition/fibrosis was seen throughout the lung interstitium surrounding the airways, blood vessels, and alveolar septae. The cysteinyl leukotriene 1 (CysLT1) receptor antagonist, MK significantly reduced the airway eosinophil infiltration, goblet cell hyperplasia, mucus occlusion, and lung fibrosis except airway smooth muscle hypertrophy in the OVA sensitized/challenged mice. The OVA sensitized/challenged mice had significantly increased epithelial desquamation compared with control mice. MK markedly reduced epithelial desquamation of airways in OVA/MK treated animals compared with OVA sensitized/challenged mice. MK treatment did not affect the levels of CysLT in lung tissue. Our results show that the important role of cysteinyl leukotrienes in the pathogenesis of asthma. Lower dose of CysLT1 receptor antagonism has a significant anti-inflammatory effect on allergen-induced lung inflammation and fibrosis but not airway smooth muscle hypertrophy in an animal model of asthma.
Respiratory Mucosa/pathology ; Receptors, Leukotriene/metabolism ; Quinolines/*therapeutic use ; Pulmonary Fibrosis/pathology ; Muscle, Smooth/pathology ; Mucus/secretion ; Mice, Inbred BALB C ; Mice ; Lung/pathology ; Leukotrienes/*biosynthesis ; Leukotriene Antagonists/*therapeutic use ; Hypertrophy ; Hyperplasia ; Goblet Cells/pathology ; Drug Evaluation, Preclinical ; Dose-Response Relationship, Drug ; Disease Models, Animal ; Cysteine/*biosynthesis ; Collagen/metabolism ; Asthma/*drug therapy/metabolism/pathology ; Anti-Asthmatic Agents/*therapeutic use ; Animals ; Airway Obstruction/drug therapy/pathology ; Acetates/*therapeutic use