Histamine H4 receptor expression is elevated in human nasal polyp tissue

Altered histamine metabolism is thought to be involved in the pathomechanism of nasal polyposis characterized by local eosinophil infiltration. The present study was performed to determine whether histamine receptors play a role in the effect of histamine in nasal polyp tissue. The findings suggest that the expression of HI and H4 receptors is elevated in polyp tissue (p = 0.045; p < 0.001), while the level of H2 and H3 receptors is not increased significantly. The elevation of HI and H4 receptors' expression may indicate that the histamine related mechanisms are preferentially mediated through HI and H4 histamine receptors in the polyp tissue. Simultaneously with increased H4 receptor expression, the concentration of eosinophil cationic protein (ECP) was increased significantly in polyp tissue (p = 0.002). One may speculate that the H4 receptor mediated histamine effects have a role in eosinophil accumulation and activation in inflammatory diseases of the nasal and paranasal sinus mucosa, such as nasal polyposis. (c) 2007 International Federation for Cell Biology. Published by Elsevier Ltd. All rights reserved.