Pathophysiology of the cysteinyl leukotrienes and effects of leukotriene receptor antagonists in asthma

Association between asthma and cardiovascular disease

BACKGROUND

Epidemiological studies on the association between asthma and cardiovascular disease have reported conflicting results. This cross-sectional study evaluated the association between asthma and ischaemic heart disease (IHD)/stroke in Korean adults.

MATERIALS AND METHODS

Data from the Korean Genome and Epidemiology Study-Health Examinees were used. Among 173 209 participants, 3162 asthmatic and 159 408 control participants were selected. Histories of asthma, IHD and stroke were obtained. Participants were categorized according to their current status of asthma management: 'well-controlled', 'being treated', and 'not being treated'. Crude and adjusted (age, gender, body mass index, income, smoking, alcohol consumption, hypertension, diabetes, dyslipidaemia and nutritional intake) odds ratios (ORs) for IHD and stroke in asthmatic patients were analysed using a multiple logistic regression model.

RESULTS

Participants with asthma reported a significantly higher prevalence of IHD (6.0% vs 3.0%) and stroke (2.3% vs 1.4%) than those without asthma (P < .001). Asthmatic participants had a higher OR (1.46, 95% confidence interval [CI] = 1.251-1.71, P < .001) for IHD than those without asthma. The association between asthma and IHD was significant only in patients aged ≥53 years (men: adjusted OR = 1.31, 95% CI = 1.01-1.70, P = .046; women: adjusted OR = 1.64, 95% CI = 1.32-2.03, P < .001) according to age and sex and in the 'not being treated' asthma group (adjusted OR = 1.47, 95% CI = 1.14-1.91, P = .003) according to the asthma management status. Stroke was not significantly associated with asthma (adjusted OR = 1.17, 95% CI = 0.92-1.48, P = .203) in the adjusted model and all subgroup analyses.

CONCLUSION

Asthma was associated with IHD, mainly in older patients and untreated asthma patients, but not with stroke.

Correlations of forced oscillometric bronchodilator response with airway inflammation and disease duration in asthma

INTRODUCTION

Airway resistance and reactance, measured by forced oscillometry, are used to measure the airway obstruction in patients with asthma.

OBJECTIVES

This study aimed to investigate the oscillometric bronchodilator responses in treated and untreated asthma and evaluate its association with airway inflammation and disease duration.

MATERIALS AND METHODS

This study included 30 nonsmoking patients with mild to moderate treated asthma, 25 patients with newly diagnosed untreated asthma and 29 control subjects. Spirometric and oscillometric measurements were performed before and after inhalation of 400 µg salbutamol. Disease duration was defined as the number of years since asthma diagnosis.

RESULTS

At airway resistance of 5 Hz (R5) and 20 Hz (R20), bronchodilator responses in patients with untreated and treated asthma were greater than those in control subjects. In patients with untreated asthma, higher fractional exhaled nitric oxide concentration (FeNO) levels were strongly correlated with greater reversibility of R20 (r_s  = -0.621, P < 0.001). In patients with treated asthma, there was no significant association between FeNO and oscillometric reversibility, whereas longer disease duration was significantly associated with lesser bronchodilator response at R20 (r_s  = 0.441, P < 0.05). Treated asthma patients with longer disease duration (≥10 years) showed significantly higher post-bronchodilator R5 and R20 than the treated asthma patients with shorter disease duration (<10 years).

CONCLUSION

The present study provides further evidence of an association between airway inflammation and variable airway obstruction in asthma patients and indicates that long-term disease duration could be related to poorly reversible airway resistance in patients with mild to moderate asthma.

Zafirlukast promotes insulin secretion by increasing calcium influx through L-type calcium channels

The zafirlukast has been reported to be anti-inflammatory and widely used to alleviate the symptoms of asthma. However, its influence on insulin secretion in pancreatic β-cells has not been investigated. Herein, we examined the effects of zafirlukast on insulin secretion and the potential underlying mechanisms. Among the cysteinyl leukotriene receptor 1 antagonists, zafirlukast, pranlukast, and montelukast, only zafirlukast enhanced insulin secretion in a concentration-dependent manner in both low and high glucose conditions and elevated the level of [Ca²⁺ ]_i , further activating Ca²⁺ /calmodulin-dependent protein kinase II (CaMKII), protein kinase B (AKT), and extracellular signal-regulated kinase (ERK) signaling. These effects were nearly abolished by the L-type Ca²⁺ channel antagonist nifedipine, while treatment with thapsigargin, a sarco/endoplasmic reticulum Ca²⁺ ATPase inhibitor, did not have the same effect, suggesting that zafirlukast primarily induces the entry of extracellular Ca²⁺ rather than intracellular Ca²⁺ from the endoplasmic reticulum. Zafirlukast treatment resulting in a significant drop in glucose levels and increased insulin secretion in C57BL/6J mice. These findings will contribute to an improved understanding of the side effects of zafirlukast and potential candidate for a therapeutic intervention in diabetes.

Enzymatic Carbon-Sulfur Bond Formation in Natural Product Biosynthesis

Sulfur plays a critical role for the development and maintenance of life on earth, which is reflected by the wealth of primary metabolites, macromolecules, and cofactors bearing this element. Whereas a large body of knowledge has existed for sulfur trafficking in primary metabolism, the secondary metabolism involving sulfur has long been neglected. Yet, diverse sulfur functionalities have a major impact on the biological activities of natural products. Recent research at the genetic, biochemical, and chemical levels has unearthed a broad range of enzymes, sulfur shuttles, and chemical mechanisms for generating carbon-sulfur bonds. This Review will give the first systematic overview on enzymes catalyzing the formation of organosulfur natural products.