Role of osteopontin in the calcification of chronic otitis media

鼓膜硬化是一种导致中耳钙化过程的疾病，通常在中耳慢性炎症后发生。由于骨桥蛋白（osteopontin， OPN）参与了病理性钙化，我们在这里研究了OPN是否参与了鼓室硬化的钙化过程。对鼓膜硬化和慢性中耳炎患者的鼓膜和中耳粘膜根据钙化程度进行组织学分类。在宏观钙化的透明化组织和微观钙化的纤维组织中，钙化灶中也发现了OPN，并且通过原位杂交测定，在其灶周围有许多表达OPN mrna的细胞。此外，OPN和CD68免疫组化双染色显示，表达OPN的细胞CD68阳性，表明这些细胞是巨噬细胞。在无钙化的炎症组织中，CD68免疫组化和OPN mRNA原位杂交显示，大多数OPN mRNA表达细胞CD68阳性。逆转录聚合酶链反应也显示了炎症组织中OPN mRNA的表达。这些结果提示，渗出性巨噬细胞分泌的OPN可能是鼓室硬化钙化的重要调节因子。

Tympanosclerosis is a condition leading to a calcification process in the middle ear, and often develops after chronic inflammation of the middle ear. Since osteopontin (OPN) has been shown to participate in the pathological calcification, we here investigated whether OPN is involved in the process of calcification in tympanosclerosis. The tympanic membrane and middle ear mucosa, obtained from patients of tympanosclerosis and chronic otitis media, were histologically classified depending on the calcification degree. In hyalinized tissues with macroscopic calcification and fibrous tissues with microscopic calcification, OPN was also found in the calcifying foci, and many OPN mRNA-expressing cells, determined by in situ hybridization, located around their foci. Moreover, immunohistochemical double staining of OPN and CD68 showed that the OPN-expressing cells were CD68-positive indicating these cells were macrophages. In inflammatory tissues without calcification, immunohistochemistry of CD68 and in situ hybridization of OPN mRNA revealed that most OPN mRNA-expressing cells were CD68-positive. The expression of OPN mRNA in inflammatory tissues was also shown by reverse transcriptase polymerase chain reaction. These results suggested that OPN secreted by exudate macrophages might be an important regulator in the calcification of tympanosclerosis.