Royal Jelly InhibitsPseudomonas aeruginosaAdherence and Reduces Excessive Inflammatory Responses in Human Epithelial Cells

Abstract

Pseudomonas aeruginosais a Gram-negative bacterium and causes respiratory infection especially in elderly patients. Royal jelly has been used worldwide as a traditional remedy and as a nutrient; however, the effect againstP. aeruginosais unclear. The aim of this study was to analyze antibacterial, antiadherent, and anti-inflammatory effects of royal jelly againstP. aeruginosa. Wild-type strain PAO1 and clinical isolates ofP. aeruginosawere used for antibacterial assay and antiadherent assay to abiotic surface and epithelial cells, which are pharynx (Detroit 562) and lung (NCI-H292) epithelial cells. In anti-inflammatory assay, epithelial cells were pretreated with royal jelly before bacterial exposure to investigate its inhibitory effect on interleukin (IL-8) and macrophage inflammatory protein-3α/CCL20 overproduction. Although royal jelly did not have antibacterial activity at concentration of 50% w/v, antiadherent activity was confirmed on the abiotic surface and epithelial cells under concentration of 25%. Pretreatment with royal jelly significantly inhibited overproduction of IL-8 and CCL20 from both cells. These results demonstrated that royal jelly inhibitsP. aeruginosaadherence and protects epithelial cells from excessive inflammatory responses againstP. aeruginosainfection. Our findings suggested that royal jelly may be a useful supplement as complementary and alternative medicine for preventing respiratory infection caused byP. aeruginosa.