Cysteinyl leukotrienes: an innate system for epithelial control of airway smooth muscle proliferation?

The Enhanced Adhesion of Eosinophils Is Associated with Their Prolonged Viability and Pro-Proliferative Effect in Asthma

Before eosinophils migrate into the bronchial lumen, they promote airway structural changes after contact with pulmonary cells and extracellular matrix components. We aimed to investigate the impact of eosinophil adhesion to their viability and pro-proliferative effect on airway smooth muscle (ASM) cells and pulmonary fibroblasts during different asthma phenotypes. A total of 39 individuals were included: 14 steroid-free non-severe allergic asthma (AA) patients, 10 severe non-allergic eosinophilic asthma (SNEA) patients, and 15 healthy control subjects (HS). For AA patients and HS groups, a bronchial allergen challenge with Dermatophagoides pteronysinnus was performed. Individual combined cells cultures were prepared between isolated peripheral blood eosinophils and ASM cells or pulmonary fibroblasts. Eosinophil adhesion was measured by evaluating their peroxidase activity, cell viability was performed by annexin V and propidium iodide staining, and proliferation by Alamar blue assay. We found that increased adhesion of eosinophils was associated with prolonged viability (p < 0.05) and an enhanced pro-proliferative effect on ASM cells and pulmonary fibroblasts in asthma (p < 0.05). However, eosinophils from SNEA patients demonstrated higher viability and inhibition of pulmonary structural cell apoptosis, compared to the AA group (p < 0.05), while their adhesive and pro-proliferative properties were similar. Finally, in the AA group, in vivo allergen-activated eosinophils demonstrated a higher adhesion, viability, and pro-proliferative effect on pulmonary structural cells compared to non-activated eosinophils (p < 0.05).

[Association of cytoplasmic phospholipase A2 gene polymorphism with bronchial asthma and response to montelukast in children]

OBJECTIVE

To study the association of cytoplasmic phospholipase A2 (PLA2G4) rs932476 polymorphism with the development of bronchial asthma and the response to montelukast, a leukotriene receptor antagonist, in children.

METHODS

A total of 128 children with bronchial asthma were enrolled as case group, and 100 healthy children were enrolled as control group. The genotype and allele frequencies of PLA2G4 rs932476 were compared between the two groups. The children in the case group were administered with montelukast except routine treatment for 2 months, and the changes in serum levels of leukotriene B4 (LTB4), interleukin-4 (IL-4), immunoglobulin E (IgE), and interferon gamma (IFN-γ), pulmonary function and fractional exhaled nitric oxide (FeNO) after treatment were observed.

RESULTS

There were no significant differences in the genotype and allele frequencies of PLA2G4 rs932476 between the case and control groups, as well as between the groups with different severities of asthma (P>0.05). After treatment, the children with AA genotype had a significantly higher overall response rate than those with GG genotype. After treatment, the case group had significant reductions in the serum levels of IgE and IL-4 and a significant increase in the level of IFN-γ (P<0.05). After treatment, the children with GG genotype had a higher serum level of IL-4 and a lower level of IFN-γ than those with AA genotype. After treatment, the case group had significant increases in pulmonary function parameters, and the children with AA genotype had significantly higher parameters than those with GG genotype. The case group had a significant reduction in the level of FeNO, and the children with AA genotype had a significantly lower level than those with GG genotype after treatment. The case group had a significantly higher serum level of LTB4 than the control group before treatment (P<0.05). After treatment the case group had a significant reduction in the serum level of LTB4 (P<0.05). The children with GG genotype had a significantly higher level of LTB4 than those with AA genotype after treatment (P<0.05).

CONCLUSIONS

PLA2G4 rs932476 polymorphism is not associated with the susceptibility and severity of bronchial asthma in children, but it may has certain influence on children's response to the leukotriene receptor antagonist montelukast, possibly by affecting the level of LTB4.

[Association of cytoplasmic phospholipase A2 gene polymorphism with bronchial asthma and response to montelukast in children]

OBJECTIVE

To study the association of cytoplasmic phospholipase A2 (PLA2G4) rs932476 polymorphism with the development of bronchial asthma and the response to montelukast, a leukotriene receptor antagonist, in children.

METHODS

A total of 128 children with bronchial asthma were enrolled as case group, and 100 healthy children were enrolled as control group. The genotype and allele frequencies of PLA2G4 rs932476 were compared between the two groups. The children in the case group were administered with montelukast except routine treatment for 2 months, and the changes in serum levels of leukotriene B4 (LTB4), interleukin-4 (IL-4), immunoglobulin E (IgE), and interferon gamma (IFN-γ), pulmonary function and fractional exhaled nitric oxide (FeNO) after treatment were observed.

RESULTS

There were no significant differences in the genotype and allele frequencies of PLA2G4 rs932476 between the case and control groups, as well as between the groups with different severities of asthma (P>0.05). After treatment, the children with AA genotype had a significantly higher overall response rate than those with GG genotype. After treatment, the case group had significant reductions in the serum levels of IgE and IL-4 and a significant increase in the level of IFN-γ (P<0.05). After treatment, the children with GG genotype had a higher serum level of IL-4 and a lower level of IFN-γ than those with AA genotype. After treatment, the case group had significant increases in pulmonary function parameters, and the children with AA genotype had significantly higher parameters than those with GG genotype. The case group had a significant reduction in the level of FeNO, and the children with AA genotype had a significantly lower level than those with GG genotype after treatment. The case group had a significantly higher serum level of LTB4 than the control group before treatment (P<0.05). After treatment the case group had a significant reduction in the serum level of LTB4 (P<0.05). The children with GG genotype had a significantly higher level of LTB4 than those with AA genotype after treatment (P<0.05).

CONCLUSIONS

PLA2G4 rs932476 polymorphism is not associated with the susceptibility and severity of bronchial asthma in children, but it may has certain influence on children's response to the leukotriene receptor antagonist montelukast, possibly by affecting the level of LTB4.

Age dictates a steroid-resistant cascade of Wnt5a, transglutaminase 2, and leukotrienes in inflamed airways

BACKGROUND

Airway remodeling is a detrimental and refractory process showing age-dependent clinical manifestations that are mechanistically undefined. The leukotriene (LT) and wingless/integrase (Wnt) pathways have been implicated in remodeling, but age-specific expression profiles and common regulators remained elusive.

OBJECTIVE

We sought to study the activation of the LT and Wnt pathways during early- or late-onset allergic airway inflammation and to address regulatory mechanisms and clinical relevance in normal human bronchial epithelial cells (NHBEs) and nasal polyp tissues.

METHODS

Mice were sensitized with house dust mite (HDM) allergens from days 3, 15, or 60 after birth. Remodeling factors in murine bronchoalveolar lavage fluid, lung tissue, or human nasal polyp tissue were analyzed by means of Western blotting, immunoassays, or histology. Regulatory mechanisms were studied in cytokine/HDM-stimulated NHBEs and macrophages.

RESULTS

Bronchoalveolar lavage fluid LT levels were increased in neonatal and adult but reduced in juvenile HDM-sensitized mice. Lungs of neonatally sensitized mice showed increased 5-lipoxygenase levels, whereas adult mice expressed more group 10 secretory phospholipase A₂, Wnt5a, and transglutaminase 2 (Tgm2). Older mice showed colocalization of Wnt5a and LT enzymes in the epithelium, a pattern also observed in human nasal polyps. IL-4 promoted epithelial Wnt5a secretion, which upregulated macrophage Tgm2 expression, and Tgm2 inhibition in turn reduced LT release. Tgm2, group 10 secretory phospholipase A₂, and LT enzymes in NHBEs and nasal polyps were refractory to corticosteroids.

CONCLUSION

Our findings reveal age differences in LT and Wnt pathways during airway inflammation and identify a steroid-resistant cascade of Wnt5a, Tgm2, and LTs, which might represent a therapeutic target for airway inflammation and remodeling.