PDE4 inhibitors have no effect on eotaxin expression in human primary bronchial epithelial cells.

The bronchial epithelium is a very important factor during the inflammatory response, it produces many key regulators involved in the pathophysiology of asthma and COPD. Local influx of eosinophils, basophils, Th2 lymphocytes and macrophages is the source of many cytotoxic proteins, cytokines and other mediators of inflammation. These cells are attracted by eotaxins (eotaxin-1/CCL11, eotaxin-2/CCL24, eotaxin-3/CCL26). Inhibitors of phosphodiesterase 4 (PDE4) are new anti-inflammatory drugs which cause cAMP accumulation in the cell and inhibit numerous stages of allergic inflammation. The aim of our study was to evaluate the influence of PDE4 inhibitors: rolipram and RO-20-1724 on the expression of eotaxins in human primary bronchial epithelial cells. Cells were preincubated with PDE4 inhibitors for 1 hour and then stimulated with IL-4 or IL-13 alone or in combination with TNF-α. After 48 hours, eotaxin protein level was measured by ELISA and mRNA level by real time PCR. These cells produce CCL24 and CCL26. PDE4 inhibitors increased CCL24 and CCL26 mRNA level irrespectively of the used stimulators. Rolipram and RO-20-1724 had no effect on eotaxin protein production in our experimental conditions. Thus PDE4 inhibitors have no effect on eotaxin protein expression in human primary bronchial epithelial cells. In vitro experiments should be performed using a primary cell model rather than immortalized lines.