Iloprost is an inhaled drug currently used to treat individuals with pulmonary arterial hypertension (raised blood pressure in the blood vessels in the lungs that leads to shortness of breath, dizziness and fainting). However, the results of a new study in mice indicate that iloprost might provide an effective therapeutic for the treatment of individuals with allergic asthma.
Iloprost is a stable analog of the naturally occurring soluble factor PGI2. It is used to treat pulmonary arterial hypertension because it causes blood vessels to widen, thereby increasing blood flow and reducing blood pressure. However, recent studies have indicated that PGI2, and therefore iloprost, might also have anti-inflammatory properties. In a study that appears in the February issue of the Journal of Clinical Investigation, Bart Lambrecht and colleagues show that inhalation of iloprost inhibits the Th2 cell inflammatory response that causes disease in a mouse model of allergic asthma. Inhalation of iloprost inhibited this response in two ways. First, it prevented the immune cells in the lungs that activate the Th2 cell response (known as dendritic cells [DCs]) from leaving the lungs and going to the site at which they activate the allergic Th2 cell response. Second, it blocked the DCs becoming activated enough to stimulate an allergic Th2 cell response. This study therefore indicates that targeting DCs in the lungs can suppress allergic asthma in mice and might lead to studies determining whether such targeting by iloprost can provide a new treatment for individuals with asthma.