[Alterations of the basal membrane in middle ear cholesteatoma]. / Alteraciones de la membrana basal en el colesteatoma de oído medio.

Cholesteatoma epithelium is characterized by a keratinocyte disregulation accompanied by destruction of the ossicles and other bony parts of the temporal bone. Immunohistochemical methods using antibodies to fibronectin, tenascin and metalloproteinases were used to assess the alterations of the instrinsic and extrinsic components of the basement membrane. Spatial orientation of the basement membrane was preserved in histological sections. Collagen type IV, tenascin, fibronectin, basic fibroblastic growth factor (bFGF), and matrix metalloproteinases (MMPs) are related to the matrix, perimatrix of normal or pathological tissues. They were studied immunohistologically in twenty cholesteatomas, eight samples of normal auditory canal skin, and six specimens of normal middle ear mucosa. Cholesteatomas displayed alterations of the basal membrane, with presence of MMPs and a linear immunoreactivity for collagen type IV and laminin, disrupted in areas with intense inflammation. The electronic microscope revealed protrusions, duplications, thickening and disruptions of the lamina densa of the basement membrane. Thus, we conclude, that MMPs and bFGF could play an important role maintaining the proliferative activity and the aggressive behaviour of cholesteatoma in the middle ear.

Alteraciones de la membrana basal en el colesteatoma de oído medio / Alterations of the basal membrana in middle ear cholesteatoma

El epitelio del colesteatoma se caracteriza por una disregulación de los queratinocitos acompañada de una destrucción de la cadena osicular y de otras partes óseas del hueso temporal. Los métodos inmunohistoquímicos con anticuerpos a la fibronectina, la tenascina y a las metaloproteinasas pueden emplearse para evaluar las alteraciones de los componentes intrínsecos y extrínsecos de la membrana basal. La orientación espacial queda preservada en los cortes histológicos. El colágeno tipo IV, la tenascina, la fibronectina, el factor básico de crecimiento fibroblástico (bFGF) y las metaloproteinasas de la matriz (MMP) están relacionadas con la matriz y perimatriz de tejido normal y alterado, por los que se estudian inmunohistoquímicamente, en 20 colesteatomas, 8 muestras de piel normal de CAE y 6 biopsias de mucosa normal de oídomedio. Los colesteatomas presentaron alteraciones de la membrana basal con la presencia anormal de MMP y una inmunorreactividad linear para el colágeno tipo IV y la laminina, interrumpida en zonas con una inflamación intensa. El microscopio electrónico evidenció protrusiones, duplicaciones, engrosamientos y rupturas de la lámina densa de la membrana basal. Se concluye, que las MMPs y el bFGF podrían tenerr un papel importante en el mantenimiento de la actividad proliferativa y del comportamiento agresivo del colesteatoma de oído medio (AU)

Cholesteatoma epithelium is characterized by a keratinocyte disregulation accompanied by destruction of the ossicles and other bony parts of the temporal bone. Immunohistochemical methods using antibodies to fibronectin, tenascin and metalloproteinases were used to assess the alterations of the instrinsic and extrinsic components of the basement membrane. Spatial orientation of the basement membrane was preserved in histological sections. Collagen type IV, tenascin, fibronectin, basic fibroblastic growth factor (bFGF), and matrix metalloproteinases (MMPs) are related to the matrix, perimatrix of normal or pathological tissues. They were studied immunohistologically in twenty cholesteatomas, eight samples of normal auditory canal skin, and six specimens of normal middle ear mucosa. Cholesteatomas displayed alterations of the basal membrane, with presence of MMPs and a linear immunoreactivity for collagen type IV and laminin, disrupted in areas with intense inflammation. The electronic microscope revealed protrusions, duplications, thickening and disruptions of the lamina densa of the basement membrane. Thus, we conclude, that MMPs and bFGF could play an important role maintaining the proliferative activity and the aggressive behaviour of cholesteatoma in the middle ear (AU)