Liquiritigenin enhances cyclic adenosine monophosphate production to mitigate inflammation in dendritic cells.

OBJECTIVE: This study aims to dissect the mechanism of traditional Chinese medicinal herbs against asthma; we chose to first focus on the main chemical components of licorice to investigate their contribution to asthmatic inflammation inhibition. METHODS: Production of cellular nucleotide molecules such as cAMP, cGMP, and cGAMP was examined by using enzyme-linked immunosorbent assay (ELISA). Enzyme-encoding genes were tested in vitro using quantitative real-time PCR and protein level was detected by Western blotting analysis. In addition, co-culturing of murine dendritic cells together with T cells was conducted to examine the expression of cytokine genes and host immune response. RESULTS: We found that one of the components within licorice, named liquiritigenin (LR), could efficiently enhance cAMP production in different cell lines. The augmentation of such molecules was linked to the high expression of cAMP synthesis genes and repressed expression of cAMP breaking down genes. In addition, the downstream immune response was also alleviated by the increase in cAMP levels by LR, suggesting the great potential of this molecule against inflammation. Subsequent immunological tests showed that LR could efficiently inhibit the expression of several cytokines and alter the NF-κB pathway and T cell polarization. CONCLUSION: Altogether, we have identified a promising antiasthmatic agent LR that could exhibit immunosuppressive function by elevating the cAMP level.

High dose of maternal folic acid supplementation is associated to infant asthma.

Maternal folic acid supplementation had a positive effect on preventing neural tube defects (NTDs), but its effects in infant asthma remained unclear. A hospital-based case-control study was conducted with outpatients between March 2010 and March 2011 including 150 onset infant asthma cases and 212 controls, together with a meta-analysis involving 14,438 participants, was performed. The association between maternal folic acid supplementation and the risk of infant asthma was not significant either in the meta-analysis (OR = 1.06, 95% CI =0.99-1.14) or in the case-control study (OR = 0.72, 95% CI =0.37-1.39). However, quantitative analysis of the supplementation dose demonstrated that the risk of infant asthma significantly increased for the infants whose mother were with high-dose supplementation (>72,000 µg•d; OR = 3.16, 95% CI =1.15-8.71) after adjusting for confounding factors in the case-control study. Meanwhile, the risk of infant asthma significantly decreased for the infants whose mother were with low-dose supplementation (<36,000 µg•d; OR = 0.36, 95% CI =0.17-0.77). A high dose of folic acid supplementation for mother during pregnancy was associated with an increased risk of infant asthma, whereas supplementation with a relatively low-dose was associated with a decreased risk of infant asthma. These findings should be further investigated in a large population.