A new compound, 1H,8H-pyrano[3,4-c]pyran-1,8-dione, suppresses airway epithelial cell inflammatory responses in a murine model of asthma

Clinical and experimental studies have established eosinophilia as a sign of allergic disorders. Activation of eosinophils in the airways is believed to cause epithelial tissue injury, contraction of airway smooth muscle and increased bronchial responsiveness. As part of the search for new antiasthmatic agents produced by medicinal plants, the effects of 270 standardized medicinal plant extracts on cytokine-activated A549 human lung epithelial cells were evaluated. After several rounds of activity-guided screening, the new natural compound, 1H,8H-Pyrano[3,4-c]pyran-1,8-dione (PPY), was isolated from Vitex rotundifolia L. To elucidate the mechanism by which the anti-asthmatic responses of PPY occurred in vitro, lung epithelial cells (A549 cell) were stimulated with TNF-alpha, IL-4 and IL-1beta to induce the expression of chemokines and adhesion molecules involved in eosinophil chemotaxis. PPY treatments reduced the expression of eotaxin, IL-8, IL-16 and VCAM-1 mRNA significantly. Additionally, PPY reduced eotaxin secretion in a dose-dependent manner and significantly inhibited eosinophil migration toward A549 medium. In addition, PPY treatment suppressed the phosphorylation of p65 and ERK1/2, suggesting that it can inhibit the MAPK/NF-KB pathway. To clarify the anti-inflammatory and antiasthmatic effects of PPY in vivo, we examined the influence of PPY on the development of pulmonary eosinophilic inflammation in a murine model of asthma. To accomplish this, mice were sensitized and challenged with ovalbumin (OVA) and then examined for the following typical asthmatic reactions: an increase in the number of eosinophils in BALF; the presence of Th2 cytokines such as IL-4 and IL-5 in the BALF; the presence of allergen-specific IgE in the serum; and a marked influx of inflammatory cells into the lung. Taken together, our results revealed that PPY exerts profound inhibitory effects on the accumulation of eosinophils into the airways while reducing the levels of IL-4, IL-5, and IL-13 in the BALF. Therefore, these results suggest that PPY may be useful as a new therapeutic drug for the treatment of allergic asthma.

Effects of bee venom on the maturation of murine dendritic cells stimulated by LPS

AIM OF STUDY

This study was performed to elicit the effectiveness of bee venom (BV), a traditional immunosuppressive Korean acupuncture agent, on the maturation of dendrtic cells (DCs).

MATERIALS AND METHODS

Immature dendritic cells (iDCs) were generated from mouse bone marrow cells with GM-CSF. After 10 days of initial differentiation, DCs were activated with lipopolysaccharides (LPS) for another 48h in the presence or absence of BV. Surface molecule analysis, intracytoplasmic staining of cytokines, FITC-conjugated antigen uptake, and transwell migration assays were conducted with iDCs and activated DCs.

RESULTS

Up-regulation of costimulatory molecules, typical of mature DCs (mDCs) was inhibited by addition of BV. Pro-inflammatory cytokines were also found to be reduced with BV treatment in LPS-stimulated DC. A decrease in antigen uptake upon the maturation of DC was reversed in low dose BV treated mDC. In addition, BV treated mDC demonstrated reduced directional migration in response to CCL21, a lymphoid chemokine which directs mDC.

CONCLUSIONS

BV may have a therapeutic effect an on abnormally activated immune status, such as autoimmune rheumatoid arthritis, through an immune-modulatory effect on DC.