Eupatoriopicrin may modulate lipopolysaccharide-induced inflammation in human respiratory epithelium

Lungs represent the largest epithelial surface in the body and is a major portal of entry for pathogens. Lipopolysaccharide (LPS) is an important antigenic component of Gram-negative bacteria, and is a potent stimulus to local and systemic immune responses. The stimulation of Toll-like receptor 4 (TLR4) by LPS activates Myd88 pathway, what leads to release of proinflammatory cytokines, and, consequently, increase chemotaxis of leukocytes. Prolonged exposure to LPS significantly decrease cell viability of epithelial cells and intensify the necrosis.

Therefore we tested the hypothesis that eupatoriopicrin may modulate LPS-induced inflammatory response. To verify this hypothesis we used lung adenocarcinoma cells (A549) and normal bronchial epithelial cells (NHBE) and verified the influence of eupatoriopicrin (tested at 0.25–2.5 µM) on: (I) integrity of cellular membrane using propidium iodide staining, (II) expression of adhesive molecules analyzed by flow cytometry, (III) modulation of TLR4-Myd88 pathway on epithelium using flow cytometry and immunoblotting analysis, (IV) cytokine release performed by ELISA tests and (V) apoptosis of epithelium analyzed by flow cytometry.

Our observations showed that eupatoriopicrin-treated cells significantly decreased TLR4 expression resulted in Myd88 phosphorylation level decrease in A549 cells. We noticed suppression of the release of IL-6, IL-8 and TNFα in both epithelial models. Interestingly, we observed that eupatoriopicrin decreased the number of necrotic cells and increased apoptosis.

Eupatoriopicrin through modulation of the LPS-induced signal transduction is interesting candidate for further evaluation as potential therapeutic agents in a treatment of inflammation-based pulmonary diseases.

• References

• 1 MacRedmond R, Greene C, Taggart CC, McElvaney N, O’Neill S. Respiratory epithelial cells require Toll-like receptor 4 for induction of Human β-defensin 2 by Lipopolysaccharide. Respir Res 2005; 6: 116