Localization of osteopontin at calcification sites of cholesteatoma: possible role as a regulator of deposition of calcium phosphate in the middle ear.

Objective: Recently, we showed that osteopontin (OPN), a major acidic phosphorylated glycoprotein of bone, participates in the pathological calcification that occurs as a result of chronic otitis media. To investigate the possibility of OPN as a common regulator of the pathological calcification in the middle ear, we here examined whether or not OPN is localized at the calcification sites of cholesteatoma, which is clearly different from chronic otitis media in the pathogenesis.

Methods: Middle ear tissues including cholesteatoma were obtained from 32 cases who underwent tympanoplasty.

Expression of the intermediate filament nestin in gastrointestinal stromal tumors and interstitial cells of Cajal.

It has recently been proposed that gastrointestinal stromal tumors (GISTs) originate from stem cells that differentiate toward a phenotype of interstitial cells of Cajal (ICCs). Nestin is a newly identified intermediate filament protein, and is predominantly expressed in immature cells, such as neuroectodermal stem cells and skeletal muscle progenitor cells, and tumors originating from these cells. In this study, we examined, using immunohistochemistry, the nestin expression in GISTs and ICCs to clarify the origin of GISTs.

Expression of osteopontin by exudate macrophages in inflammatory tissues of the middle ear: a possible association with development of tympanosclerosis.

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.

Interleukin-18 up-regulates osteoprotegerin expression in stromal/osteoblastic cells.

Osteoprotegerin (OPG) and osteoclast differentiation factor (ODF) are crucial regulators of osteoclastogenesis. To determine the biological role of interleukin (IL)-18 produced by stromal/osteoblastic cells in osteoclastogenesis, we examined the effects of IL-18 on the OPG and ODF mRNA levels in these cells. When bone marrow stromal ST2 cells, osteoblastic MC3T3-E1 cells, and mouse calvarial osteoblasts were stimulated with IL-18, the expression of OPG mRNA, but not ODF mRNA, was transiently increased, its expression reaching a maximal level at 3 h after the beginning of the culture.