The leukotriene C(4) synthase gene and asthma

The role of puff volume in vaping emissions, inhalation risks, and metabolic perturbations: a pilot study

Secondhand vaping exposure is an emerging public health concern that remains understudied. In this study, saliva and exhaled emissions from ENDS users (secondhand) and non-ENDS users (baseline) were collected, firsthand emissions were generated using an automated ENDS aerosol generation system programmed to simulate puffing topography profiles collected from ENDS users. Particulate concentrations and sizes along with volatile organic compounds were characterized. We revealed puffing topography metrics as potential mediators of firsthand and secondhand particle and chemical exposures, as well as metabolic and respiratory health outcomes. Particle deposition modeling revealed that while secondhand emissions displayed smaller deposited mass, total and pulmonary particle deposition fractions were higher than firsthand deposition levels, possibly due to smaller secondhand emission particle diameters. Lastly, untargeted metabolomic profiling of salivary biomarkers of lung injury due to firsthand ENDS exposures revealed potential early indicators of respiratory distress that may also be relevant in bystanders exposed to secondhand vaping scenarios. By leveraging system toxicology, we identified 10 metabolites, including leukotriene D4, that could potentially serve as biomarkers for ENDS use, exposure estimation, and the prediction of vaping-related disease. This study highlights characterization of vaping behavior is an important exposure component in advancing our understanding of potential health effects in ENDS users and bystanders.

Angioedema and Fatty Acids

Angioedema is a life-threatening emergency event that is associated with bradykinin and histamine-mediated cascades. Although bradykinin-mediated angioedema currently has specific therapeutic options, angioedema is sometimes intractable with current treatments, especially histamine-mediated angioedema, suggesting that some other mediators might contribute to the development of angioedema. Fatty acids are an essential fuel and cell component, and act as a mediator in physiological and pathological human diseases. Recent updates of studies revealed that these fatty acids are involved in vascular permeability and vasodilation, in addition to bradykinin and histamine-mediated reactions. This review summarizes each fatty acid’s function and the specific receptor signaling responses in blood vessels, and focuses on the possible pathogenetic role of fatty acids in angioedema.

Leukotriene C4 synthase A-444C gene polymorphism in patients with allergic rhinitis

OBJECTIVE

To determine the frequency of leukotriene C4 synthase A-444C polymorphism in allergic rhinitis patients.

STUDY DESIGN AND SETTING

A prospective, randomized, case-controlled study. Blood samples were obtained from 85 patients with allergic rhinitis and 95 healthy individuals. After the extraction of DNA from the blood samples, the leukotriene C4 synthase A-444C polymorphism was studied by a real-time polymerase chain reaction method.

RESULTS

The AC and CC genotype frequencies were statistically higher in the study group (P = 0.048 and P = 0.037, respectively). In addition, the AC polymorphism carried an increased risk of developing allergic rhinitis (odds ratio = 2.18, 95% confidence interval, 1.173-4.053, P = 0.014).

CONCLUSION

The C allele of the leukotriene C4 synthase gene increases the risk of developing allergic rhinitis.

SIGNIFICANCE

The leukotriene C4 synthase A-444C gene polymorphism is important in susceptibility to allergic rhinitis and this is the first study of this gene polymorphism in allergic rhinitis.

EBM RATING

B-3b.

Safety of a specific COX-2 inhibitor in aspirin-induced asthma

In a subset of patients with asthma, aspirin and several other non-steroidal anti-inflammatory drugs (NSAID) that inhibit simultaneously cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) precipitate dangerous asthmatic attacks. We tested the hypothesis that in patients with aspirin-induced asthma the attacks are triggered by inhibition of COX-1 and not COX-2. In twelve asthmatic patients (seven men, five women, average age 39 years) oral aspirin challenge precipitated symptoms of bronchial obstruction with fall in FEV1 > 20%, and a rise in urinary leukotriene E4 (LTE4) excretion; also in five patients the stable metabolite of PGD2, 9alpha11betaPGF2, increased in urine. The patients then entered a double-blind, placebo-controlled, cross-over study in which they received either placebo or rofecoxib in increasing doses 1.5-25.0 mg for 5 consecutive days, separated by a 1-week wash-out period. No patient on rofecoxib developed dyspnoea or fall in FEV1 > 20%; mean urinary LTE4 and 9alpha11betaPGF2 urinary levels, measured on each study day for 6 h post-dosing, remained unchanged. Two patients on placebo experienced moderate dyspnoea without alterations in urinary metabolites excretion. At least 2 weeks after completion of the study, all patients received on an open basis 25 mg rofecoxib without any adverse effects. NSAID that inhibit COX-1, but not COX-2, trigger asthmatic attacks in patients with asthma and aspirin intolerance. Rofecoxib can be administered to patients with aspirin-induced asthma.