Increased expression of high-mobility group protein B1 in chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is an inflammation of the sinonasal mucosa and many inflammatory cells and cytokines are involved in its pathogenesis. High-mobility group protein B1 (HMGB1) is a DNA-binding protein that has a proinflammatory function when secreted into extracellular space. The purpose of this study was to evaluate the expression of HMGB1 in paranasal sinus mucosa and to determine the difference of HMGB1 expression between CRS patients and normal controls.

Paranasal sinus mucosa was obtained from 10 patients with CRS and 10 patients without CRS. Semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR), real-time PCR and Western blot analysis were performed to detect mRNA and protein. Sections of the mucosa were immunostained for localization of HMGB1 and image analysis was performed.

RT-PCR and real-time PCR showed that the expression level of HMGB1 mRNA was significantly increased in the tissues of patients with CRS compared with controls. Western blot analysis showed that the expression level of HMGB1 protein was significantly increased in the tissues of CRS. In immunohistochemical staining, the HMGB1 protein was expressed in epithelial cells and inflammatory cells and the expression intensity of HMGB1 protein was stronger in CRS.

HMGB1 is increased in the paranasal sinus mucosa of patients with CRS. These results suggest a possible contribution of HMGB1 in the pathophysiology of CRS.