Emiko Ono

Increased production of cysteinyl leukotrienes and prostaglandin D2 during human anaphylaxis

Background Anaphylaxis is a life‐threatening syndrome resulting from the sudden release of mast cell‐ and basophil‐derived mediators into the circulation. However, pathological evidence of the association between inflammatory mediators and human anaphylaxis is insufficient.

Profile of eicosanoid generation in aspirin-intolerant asthma and anaphylaxis assessed by new biomarkers

BACKGROUND It has recently demonstrated that a free radical-mediated pathway generates prostaglandins (PGs) and the corresponding prostaglandin enantiomers (ent-PGs). Aspirin-intolerant asthma and anaphylaxis accompany PGD(2) overproduction, possibly associated with mast cell activation via the COX pathway. However, free radical-mediated PG generation in the pathophysiology of these diseases, which can be demonstrated by measuring urinary ent-PGF(2)alpha, has not been reported. OBJECTIVES To evaluate the characteristic profile of eicosanoid generation via the COX and/or free radical-mediated pathway underlying aspirin-intolerant asthma and anaphylaxis. METHODS A comparative group analysis consisted of asthma (n = 17) and anaphylaxis (n = 8, none with aspirin-induced anaphylaxis) cases. Urinary eicosanoid concentrations were quantified as follows: 2,3-dinor-9alpha,11beta-PGF(2) by gas chromatography-mass spectrometry; leukotriene E(4), 9alpha,11beta-PGF(2), and PGs by enzyme immunoassay. RESULTS 2,3-Dinor-9alpha,11beta-PGF(2) is a more predominant PGD(2) metabolite in urine than 9alpha,11beta-PGF(2). At baseline, the aspirin-intolerant asthma group (n = 10) had significantly higher leukotriene E(4) and lower PGE(2) concentrations in urine than the aspirin-tolerant asthma group. During the reaction, the urinary concentrations of leukotriene E(4) and PGD(2) metabolites correlatively increased, but with markedly different patterns of the mediator release, in the aspirin-intolerant asthma group and the anaphylaxis group, respectively. The urinary PGD(2) metabolites and primary PGs were significantly decreased in the aspirin-tolerant asthma group. Urinary ent-PGF(2)alpha concentrations were significantly increased in the anaphylaxis group but not the aspirin-intolerant asthma group. CONCLUSIONS When assessed by urinary 2,3-dinor-9alpha,11beta-PGF(2), PGD(2) overproduction during aspirin-intolerant bronchoconstriction was clearly identified, regardless of COX inhibition. It is evident that free radical-mediated PG generation is involved in the pathophysiology of anaphylaxis.

Exhaled breath condensate eicosanoid levels associate with asthma and its severity

BACKGROUND The relationship between anti-inflammatory lipoxins and proinflammatory leukotrienes might be important in the pathobiology and severity of asthma. OBJECTIVE We sought to investigate whether exhaled breath condensate (EBC) lipoxin and leukotriene measurements can noninvasively characterize the asthmatic diathesis and its severity. METHODS We measured lipoxin A4 (LXA4) and leukotriene B4 (LTB4) levels in EBC collected from patients with asthma of different severities and from healthy control subjects. RESULTS EBC LXA4 and LTB4 levels are increased in asthmatic patients compared with those seen in healthy control subjects (LXA4: 31.40 vs 2.41 pg/mL EBC, respectively [P < .001]; LTB4: 45.62 vs 3.82 pg/mL EBC, respectively [P < .001]). Although levels of both eicosanoids are increased in asthmatic patients, the LXA4/LTB4 ratio decreases with increasing asthma severity. It is 41% lower in patients with severe versus moderate asthma (0.52 vs 0.88, P = .034). EBC LXA4 levels correlate with the degree of airflow obstruction measured by using FEV1 (r = 0.28, P = .018). An LXA4 cutoff value of 7 pg/mL EBC provides 90% sensitivity and 92% specificity for the diagnosis of asthma (area under the curve, 0.96; P < .001). An LTB4 cutoff value of 11 pg/mL EBC provides 100% sensitivity and 100% specificity for the diagnosis of asthma (area under the curve, 1; P < .001). CONCLUSIONS Proresolving and proinflammatory eicosanoids are generated in the airways of all asthmatic patients. The proportion of proresolving compounds decreases with asthma severity. These findings support the role for EBC eicosanoid measurements in the noninvasive diagnosis of asthma and suggest that proresolving eicosanoid pathways are dysregulated in patients with severe asthma.

Differences in regulatory T cells between Churg-Strauss syndrome and chronic eosinophilic pneumonia with asthma

BACKGROUND Chronic eosinophilic pneumonia (CEP) with asthma precedes the onset of Churg-Strauss syndrome (CSS) in half of all patients with CSS. It is not known what determines whether patients with CEP after asthma will have CSS. OBJECTIVE We examined whether activation of regulatory T cells in patients with CEP inhibits CSS development and is otherwise involved in the mechanism of CSS disease. METHODS In patients with CSS (n = 38), CEP with asthma (n = 20), and general adult asthma (n = 108), we examined the number of CD4(+)CD25(+) T cells in peripheral blood, as well as levels of expression of the cytokines IL-2, IL-5, IL-10, and TGF-beta by CD4(+)CD25(+) T cells, CD4(+)CD25(-) T cells, or both. RESULTS At disease onset, patients with CSS, unlike patients with CEP, had significantly fewer CD4(+)CD25(+) T cells than patients with any step of asthma. CD4(+)CD25(+) T cells producing IL-10 were rarely detected in patients with CSS at disease onset or relapse, whereas the numbers of IL-10-producing T cells in patients with CEP were high at disease onset. There were fewer CD4(+)CD25(-) T cells producing IL-2 in patients with CSS before treatment than in patients with CEP at disease onset. The proportions of CD4(+)CD25(+) T cells producing IL-10 and CD4(+)CD25(-) T cells producing IL-2 in patients with CSS increased at remission. CONCLUSIONS Maintenance of the numbers of regulatory T cells in patients with CEP with asthma might inhibit CSS development through the action of cytokines, such as IL-10 and IL-2, produced by CD4(+)CD25(+) or CD4(+)CD25(-) T cells. This might be part of a mechanism that influences progression and prognosis in these diseases.

Lipoxin Generation Is Related to Soluble Epoxide Hydrolase Activity in Severe Asthma

RATIONALE Severe asthma is characterized by airway inflammatory responses associated with aberrant metabolism of arachidonic acid. Lipoxins (LX) are arachidonate-derived pro-resolving mediators that are decreased in severe asthma, yet mechanisms for defective LX biosynthesis and a means to increase LXs in severe asthma remain to be established. OBJECTIVES To determine if oxidative stress and soluble epoxide hydrolase (sEH) activity are linked to decreased LX biosynthesis in severe asthma. METHODS Aliquots of blood, sputum, and bronchoalveolar lavage fluid were obtained from asthma subjects for mediator determination. Select samples were exposed to t-butyl-hydroperoxide or sEH inhibitor (sEHI) before activation. Peripheral blood leukocyte-platelet aggregates were monitored by flow cytometry, and bronchial contraction was determined with cytokine-treated human lung sections. MEASUREMENTS AND MAIN RESULTS 8-Isoprostane levels in sputum supernatants were inversely related to LXA4 in severe asthma (r = -0.55; P = 0.03) and t-butyl-hydroperoxide decreased LXA4 and 15-epi-LXA4 biosynthesis by peripheral blood leukocytes. LXA4 and 15-epi-LXA4 levels were inversely related to sEH activity in sputum supernatants and sEHIs significantly increased 14,15-epoxy-eicosatrienoic acid and 15-epi-LXA4 generation by severe asthma whole blood and bronchoalveolar lavage fluid cells. The abundance of peripheral blood leukocyte-platelet aggregates was related to asthma severity. In a concentration-dependent manner, LXs significantly inhibited platelet-activating factor-induced increases in leukocyte-platelet aggregates (70.8% inhibition [LXA4 100 nM], 78.3% inhibition [15-epi-LXA4 100 nM]) and 15-epi-LXA4 markedly inhibited tumor necrosis factor-α-induced increases in bronchial contraction. CONCLUSIONS LX levels were decreased by oxidative stress and sEH activity. Inhibitors of sEH increased LXs that mediated antiphlogistic actions, suggesting a new therapeutic approach for severe asthma. Clinical trial registered with www.clinicaltrials.gov (NCT 00595114).

Urinary concentrations of 15‐epimer of lipoxin A4 are lower in patients with aspirin‐intolerant compared with aspirin‐tolerant asthma

Although an abnormality in arachidonic acid metabolism may be responsible for aspirin‐intolerant asthma (AIA), there is little knowledge about the concentrations of urinary lipoxin A4 (LXA4) and the 15‐epimer of LXA4 (15‐epi‐LXA4) in relation to asthma severity in AIA subjects.

Pseudomonas aeruginosa sabotages the generation of host proresolving lipid mediators

Significance Pseudomonas aeruginosa pulmonary infections cause prolonged and destructive inflammation for cystic fibrosis patients. Despite vigorous neutrophilic responses, P. aeruginosa persists in a chronic hyperinflammatory environment. We show that the P. aeruginosa virulence factor, cystic fibrosis transmembrane conductance regulator inhibitory factor (Cif), promotes sustained airway inflammation by reducing host pro-resolving lipid mediators. Cif hydrolyzes epithelial-derived 14,15-epoxyeicosatrienoic acid, disrupting transcellular production of the proresolving lipid 15-epi lipoxin A4 (15-epi LXA4) by neutrophils. Clinical data from cystic fibrosis patients revealed that Cif abundance correlated with increased inflammation, decreased 15-epi LXA4, and reduced pulmonary function. Our study and the recent identification of Cif homologs in Acinetobacter and Burkholderia species suggest that bacterial epoxide hydrolases represent a novel virulence strategy shared by multiple respiratory pathogens. Recurrent Pseudomonas aeruginosa infections coupled with robust, damaging neutrophilic inflammation characterize the chronic lung disease cystic fibrosis (CF). The proresolving lipid mediator, 15-epi lipoxin A4 (15-epi LXA4), plays a critical role in limiting neutrophil activation and tissue inflammation, thus promoting the return to tissue homeostasis. Here, we show that a secreted P. aeruginosa epoxide hydrolase, cystic fibrosis transmembrane conductance regulator inhibitory factor (Cif), can disrupt 15-epi LXA4 transcellular biosynthesis and function. In the airway, 15-epi LXA4 production is stimulated by the epithelial-derived eicosanoid 14,15-epoxyeicosatrienoic acid (14,15-EET). Cif sabotages the production of 15-epi LXA4 by rapidly hydrolyzing 14,15-EET into its cognate diol, eliminating a proresolving signal that potently suppresses IL-8–driven neutrophil transepithelial migration in vitro. Retrospective analyses of samples from patients with CF supported the translational relevance of these preclinical findings. Elevated levels of Cif in bronchoalveolar lavage fluid were correlated with lower levels of 15-epi LXA4, increased IL-8 concentrations, and impaired lung function. Together, these findings provide structural, biochemical, and immunological evidence that the bacterial epoxide hydrolase Cif disrupts resolution pathways during bacterial lung infections. The data also suggest that Cif contributes to sustained pulmonary inflammation and associated loss of lung function in patients with CF.

Comparison of cysteinyl leukotriene concentrations between exhaled breath condensate and bronchoalveolar lavage fluid

Background Collection of exhaled breath condensate (EBC) is a simple, non‐invasive method of obtaining samples from the airways and it can be repeated in short intervals without side effects; therefore, it provides an opportunity to monitor the changes in concentration of inflammatory mediators in the airways. However, EBC analysis still has several unresolved issues.

Obesity and aspirin intolerance are risk factors for difficult‐to‐treat asthma in Japanese non‐atopic women

Asthma is a clinical syndrome characterized by variabilities in disease expression and severity. The pathophysiological mechanism underlying anti‐asthma treatment resistance is also assumed to be different between disease phenotypes.

Aspirin-Intolerant Asthma (AIA) Assessment Using the Urinary Biomarkers, Leukotriene E4 (LTE4) and Prostaglandin D2 (PGD2) Metabolites

The clinical syndrome of aspirin-intolerant asthma (AIA) is characterized by aspirin/nonsteroidal anti-inflammatory drug intolerance, bronchial asthma, and chronic rhinosinusitis with nasal polyposis. AIA reactions are evidently triggered by pharmacological effect of cyclooxygenase-1 inhibitors. Urine sampling is a non-invasive research tool for time-course measurements in clinical investigations. The urinary stable metabolite concentration of arachidonic acid products provides a time-integrated estimate of the production of the parent compounds in vivo. AIA patients exhibits significantly higher urinary concentrations of leukotriene E(4) (LTE(4)) and 1,15-dioxo-9α-hydroxy-2,3,4,5-tetranorprostan-1,20-dioic acid (tetranor-PGDM), a newly identified metabolite of PGD(2), at baseline. This finding suggests the possibility that increased mast cell activation is involved in the pathophysiology of AIA even in a clinically stable condition. In addition, lower urinary concentrations of primary prostaglandin E(2) and 15-epimer of lipoxin A(4) at baseline in the AIA patients suggest that the impaired anti-inflammatory elements may also contribute to the severe clinical outcome of AIA. During the AIA reaction, the urinary concentrations of LTE(4) and PGD(2) metabolites, including tetranor-PGDM significantly and correlatively increase. It is considered that mast cell activation probably is a pathophysiologic hallmark of AIA. However, despite the fact that cyclooxygenease-1 is the dominant in vivo PGD(2) biosynthetic pathway, the precise mechanism underlying the PGD(2) overproduction resulting from the pharmacological effect of cyclooxygenease-1 inhibitors in AIA remains unknown. A comprehensive analysis of the urinary concentration of inflammatory mediators may afford a new research target in elucidating the pathophysiology of AIA.