Cysteinyl leukotriene receptor antagonist regulates allergic airway inflammation in an organ- and cytokine-specific manner

Salvinorin A Inhibits Airway Hyperreactivity Induced by Ovalbumin Sensitization

Salvinorin A, a neoclerodane diterpene isolated from Salvia divinorum, exerts a number of pharmacological actions which are not solely limited to the central nervous system. Recently it has been demonstrated that Salvinorin A inhibits acute inflammatory response affecting leukotriene (LT) production. Since LTs are potent lipid mediators implicated in allergic diseases, we evaluated the effect of Salvinorin A on allergic inflammation and on airways following sensitization in the mouse. Mice were sensitized with s.c. injection of ovalbumin (OVA) on days 1 and 8. Sensitized mice received on days 9 and 12 on the shaved dorsal surface air administration to induce the development of the air-pouches. On day 15 animals were challenged by injection of OVA into the air-pouch. Salvinorin A, administered (10 mg/kg) before each allergen exposure, significantly reduced OVA-induced LT increase in the air pouch. This effect was coupled to a reduction in cell recruitment and Th2 cytokine production. In another set of experiments, mice were sensitized with OVA and both bronchial reactivity and pulmonary inflammation were assessed. Salvinorin A abrogated bronchial hyperreactivity and interleukin (IL)-13 production, without effect on pulmonary inflammation. Indeed cell infiltration and peribronchial edema were still present following diterpenoid treatment. Similarly, pulmonary IL-4 and plasmatic IgE levels were not modulated. Conversely, Salvinorin A significantly reduced LTC₄ production in the lung of sensitized mice. Finally mast cell activity was evaluated by means of toluidine blue staining. Data obtained evidenced that Salvinorin A significantly inhibited mast cell degranulation in the lung. Our study demonstrates that Salvinorin A inhibits airway hyperreactivity induced by sensitization by inhibition of LT production and mast cell degranulation. In conclusion Salvinorin A could represent a promising candidate for drug development in allergic diseases such as asthma.

Have recent investigations into remission from childhood asthma helped in understanding the pathogenesis of this disease?

Studies show that a significant proportion of young people suffering from childhood onset asthma later recovered, usually in adolescence. In this article we argue that an understanding of the differences between children who recover from asthma and those who do not would contribute to increased understanding of the pathogenic mechanisms of the disease and could provide new clues about prevention and treatment. We note that some researchers have recently published results from these kinds of investigations. This paper reports results regarding genetic determinants, distorted mechanisms of inflammation, and mind/body relationships. We also try to integrate findings from these 3 areas to formulate general conclusions about the pathogenesis of asthma.

A meta-analysis of IL-13 polymorphisms and pediatric asthma risk

Background

IL13–1112C/T and +2044A/G polymorphisms have been reported to be correlated with pediatric asthma susceptibility, but study results were still debatable. Thus, a meta-analysis was conducted.

Material/Methods

PubMed and EMBASE databases were searched. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to calculate the strength of association in the random-effects model or fixed-effects model.

Results

Fourteen case-control studies with 4710 asthma cases and 6086 controls were included in this meta-analysis. IL13–1112C/T and +2044A/G polymorphisms were significantly associated with an increased risk of pediatric asthma (OR=1.14, 95% CI 1.01–1.28, P=0.04, I²=0%; OR=1.20, 95% CI 1.09–1.32, P<0.01, I²=0%), respectively. In the subgroup analysis by ethnicity, IL13–1112C/T polymorphism was significantly associated with pediatric asthma risk in whites (OR=1.29, 95% CI 1.02–1.63, P=0.03, I²=16%). IL13 +2044A/G polymorphism was significantly associated with pediatric asthma risk in Asians (OR=1.21, 95% CI 1.10–1.34, P<0.01, I²=24%).

Conclusions

The results of this meta-analysis suggest that IL13–1112C/T and +2044A/G polymorphisms contribute to the development of pediatric asthma.

Montelukast, a cysteinyl leukotriene receptor-1 antagonist protects against hippocampal injury induced by transient global cerebral ischemia and reperfusion in rats

Cysteinyl leukotrienes (CysLTs) are potent pro-inflammatory and immune modulating lipid mediators involved in inflammatory diseases and were boosted in human brain after acute phase of cerebral ischemia. The antagonism of CysLTs receptors may offer protection against ischemic damage. Therefore it seemed interesting to study the possible neuroprotective effect of Montelukast, a CysLTR1 antagonist in global cerebral ischemia/reperfusion (IR) injury in rats. Global cerebral ischemia-reperfusion was induced by bilateral carotid artery occlusion for 15 min followed by 60 min reperfusion period. Animals were randomly allocated into three groups (n = 30 per group): Sham operated, I/R control and rats treated with montelukast (0.5 mg/kg, po) daily for 7 days then I/R was induced 1 h after the last dose of montelukast. After reperfusion rats were killed by decapitation, brains were removed and both hippocampi separated and the following biochemical parameters were estimated; lactate dehydrogenase activity, oxidative stress markers (lipid peroxides, nitric oxide and reduced glutathione), inflammatory markers (myeloperoxidase, tumor necrosis factor-alpha, nuclear factor kappa-B, interleukin-6 and interleukin-10), apoptotic biomarkers (caspase 3 and cytochrome C), neurotransmitters (glutamate, gamma aminobutyric acid), Cys-LTs contents and CysLT1 receptor expression; as well as total brain infarct size and histopathological examination of the hippocampus were assessed. Montelukast protected hippocampal tissue by reducing oxidative stress, inflammatory and apoptotic markers. Furthermore, it reduced glutamate and lactate dehydrogenase activity as well as infarct size elevated by I/R. These results were consistent with the histopathological findings. Montelukast showed a neuroprotective effects through antioxidant, anti-inflammatory and antiapoptotic mechanisms.