Keratinization of middle ear cholesteatomas. I. A histochemical study of epidermal transglutaminase

Human-papillomavirus DNA in cholesteatomas

Cholesteatoma of the middle ear is a relatively common disorder, often with severe consequences. Histologically, the aggressively growing, bone-destructing form shows papillary growth and koilocytosis, which are characteristic of papillomavirus-induced lesions. A PCR (polymerase chain reaction) method using degenerate primers for the detection of any known or as yet unknown HPV (human papillomavirus) type was applied in screening 51 biopsies from 42 patients. A resulting 36% (16/45) of the cholesteatomas were found to contain papillomavirus DNA, which hybridized under stringent conditions with an HPV-II DNA probe. In 3 cases the presence of HPV-II DNA could be confirmed by sequencing the PCR products. The mere presence of this HPV DNA does not prove an etiological role of this group of viruses in the induction of cholesteatomas. It does, however, identify another group of human proliferative lesions putatively linked to papillomavirus infections.

An immunohistochemical and histochemical study of cytokeratin, involucrin and transglutaminase in seborrhoeic keratosis

The mode of differentiation of seborrhoeic keratoses was investigated by immunohistochemical staining using cytokeratin (CK) polypeptide-specific monoclonal antibodies and an antibody specific for the particulate form of epidermal transglutaminase (ETgase), and by applying an anti-human involucrin serum. The role played by (E)Tgase was further evaluated using an activity assay based on the covalent attachment of monodansylcadaverine. Samples of uninvolved epidermis served as reference tissue. CK reactivities suggested that seborrhoeic keratoses is a hyperproliferative disease with an epidermal CK composition. CK5 and CK14 were prominent markers of basal and basaloid keratinocytes, whereas a decrease in staining occurred in advanced maturation stages and areas of terminal keratinization. In contrast, CK1 and CK10 were prominent markers of suprabasaloid differentiation stages and produced complementary stainings to those of CK5 and 14. Generally, CK10 staining was more impressive than CK1 staining and seemed to start before CK1 staining. In contrast to CK10 staining, cornified areas lost CK1 reactivity. These staining patterns were similar to those observed in uninvolved reference tissues. The epidermal CK subset was further supplemented with the 'hyperproliferative' CK6 and 16 which occur sequentially. Positive staining for CK6 was noted from basal and proximal basaloid cells onwards, whereas distal basaloid cells additionally showed CK16 staining. The presence of other non-epidermal CK polypeptides could not be shown. The competence for other differentiation markers belonging to the group of (E)Tgase and cornifying cell membranes also evolved with a typical epidermal pattern. (E)Tgase activity was restricted to advanced and terminal stages of keratinization and was dual in nature, i.e. a diffuse cytoplasmic staining occurred together with a prominent staining of cornifying cell membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytoskeletal polypeptides: cell-type specific markers useful in investigative otorhinolaryngology

In the last decade, it has been established that eukaryotic cells possess a cytoskeleton, i.e. an integrated cytoplasmic network of microfilaments (MFs), microtubules (MTs) and intermediate filaments (IFs). Moreover, certain cell membrane specializations as well as the inner lamina of the nuclear membrane also participate in the cytoskeletal structure. Although this definition of the cytoskeleton is up to date it is obvious that the future course of cell biology will be reflected in a revised definition. While the bulk of structural polypeptides involved were characterized at regular intervals, surprisingly, the function of the cytoskeleton remained largely speculative and is still less precisely defined. The most widely postulated function concerns mechanical support and integration of diverse cellular activities and thus refers to cellular architecture. Briefly, the mechanical function is thought to involve cell movement, adhesive interaction with the extracellular matrix and neighbouring cells, as well as the stabilization of cell shape. The integrative function refers to intracellular movement, i.e. transport and positioning to the appropriate locations of organelles, intracellular particles, RNA and proteins. It has been established from numerous investigations that (certain) cytoskeletal polypeptides provide significant information about the cellular origin and differentiation state. This consideration constitutes the most prominent reflection underlying this review. Furthermore, this appreciation encourages additional efforts to explore these markers in normal and pathological conditions. The first purpose of this review is briefly to summarize our present comprehension of the molecular components of the cytoskeleton, restricted to the filamentous trinity for practical reasons. The second and main aim is to survey the field with respect to otorhinolaryngology-related issues. To the author's knowledge, this has not been dealt with in the past. In bridging this gap in the literature, I hope to provoke additional interest in one of the fastest moving areas of cell biology. A comprehensive review covering the whole cytoskeleton has been covered by Preston et al. (The Cytoskeleton and Cell Motility. Blackie, Glasgow and London, 1990, pp. 7-69, 188-191). Additional information on the participating substructures is provided in the text, inclusive of last year's reviews.

Immunohistochemical analysis of the cytokeratin expression in middle ear cholesteatoma and related epithelial tissues

Immunohistochemical investigations were carried out to determine the pattern of cytokeratin (CK) expression in middle ear cholesteatoma and related epithelia. Using monoclonal antibodies specific for CK chains and the indirect immunoperoxidase technique, we examined 10 CK polypeptides for expression. The external stratified squamous epithelium of the tympanic membrane generally expressed CKs 5, 10, and 14. In addition, basal keratinocytes in the annular region of the pars tensa expressed CK 19 (a simple epithelium marker), while suprabasally the hyperproliferative marker CK 16 was expressed. These data reflect the unusual proliferative nature of this region. The unexpected appearance of CK 16 (known to have a limited distribution in healthy epidermis) clearly relates to its expression in the neighboring deep meatus. The medial simple epithelium of the eardrum revealed mucosal CKs 7, 8, 14, 18, and 19. Acquired cholesteatoma lesions, besides CKs 5, 10, and 14, consistently expressed CK 16 in suprabasal layers. These results constitute the first direct molecular evidence for the hyperproliferative nature of the cholesteatoma matrix. Overall, our CK data suggest that aural cholesteatoma lesions and epidermal tissue in this area are related. However, they do not explain the mechanism(s) by which the eardrum or meatal epithelia might invade the middle ear cavity. Congenital cholesteatomas expressed CKs 5, 10, 14, and 16 equally. These CK data do not support the idea of a metaplastic origin from middle ear mucosa; instead, they suggest activation of an ectodermal rest in the middle ear cavity.

Keratinization of middle ear cholesteatomas. II. A histochemical study of epidermal transglutaminase substrates

A histochemical study was performed to clarify further the role played by epidermal transglutaminase (ETgase) in the keratinization of aural cholesteatoma. Weakly and strongly keratinized epidermal tissues and healthy middle ear mucosa were included as references. A first assay revealed the distribution of non-specified acyl donor substrates. In a second assay, the topography of involucrin was assessed immunohistochemically. In both epidermal and cholesteatoma matrix tissues, the presence of acyl donors was not restricted to the sites of (E)Tgase activity, but was almost uniformly extended throughout living layers. In reference tissues, residual acyl donors were poorly detected in horny layers, while they were more abundant in the stratum corneum of the cholesteatomas studied. The presence of involucrin along the cell membrane was observed at varying distances throughout the spinous and granular layers, depending upon the epidermal and matrix configurations. In thick epithelia, involucrin rapidly became concentrated at the cell periphery (in spinous keratinocytes), while in thin epithelia it was usually associated with cell flattening. This latter staining profile was observed more frequently in cholesteatomatous tissues. In addition, we regularly noticed an immediately suprabasal accumulation of involucrin, suggesting a locally hyperproliferative state of the matrix. An insufficient availability of acyl donors, especially involucrin, could not be used to explain the defective ETgase-mediated cross-linking of cholesteatoma cell membranes during terminal stages of differentiation. The present investigation may be the first to demonstrate the presence of involucrin in middle ear mucosa.