Normal Auditory Canal Skin Research Articles

Expression of the receptor activator for nuclear factor- κB ligand and osteoprotegerin in chronic otitis media

Background The receptor activator for nuclear factor- κB ligand (RANKL) and osteoprotegerin (OPG) are the key factors controlling the osteoclast and osteoblast action in the bone. Purpose The study objective was to investigate the expression level of RANKL and OPG in cholesteatoma and granulation tissue, and to assess the relationship between their expression levels and osteolysis. Material and methods Patients with chronic otitis media with cholesteatoma (n = 28) and without cholesteatoma (n = 24) treated surgically at the Department of Otolaryngology of the Medical University of Gdańsk were included in the study. RANKL and OPG expressions were analyzed by immunohistochemistry and Western blot. Results RANKL and OPG were expressed in all cholesteatoma and granulation tissues. RANKL expression was mainly observed in cholesteatoma subepithelial stroma, whereas OPG-positive cells originated from the epithelium. The number of OPG-positive cells in the normal skin was significantly higher than in cholesteatoma tissues. The RANKL protein level in cholesteatoma tissues was 1.8- and 1.5-fold higher than in the auditory canal skin and granulation tissues, respectively. The number of RANKL-positive cells in cholesteatoma tissues was significantly higher than in the normal skin. No substantial differences were found in average OPG protein levels between cholesteatoma tissues and the normal auditory canal skin. The ratio of RANKL/OPG was significantly higher in cholesteatoma tissues (2.93 ± 0.79) than in the skin samples (1.36 ± 0.34). Conclusions Altered ratio of RANKL/OPG protein level in cholesteatoma tissues suggests that these proteins might be somehow involved in the pathogenesis of cholesteatoma. However, to resolve this issue a study on a larger group of patients should be conducted.

Down-regulation of Toll-like receptor 4 in the granulation tissues of postoperative mastoid cavities with otorrhea

Conclusions. The expression of toll-like receptor (TLR) 4 and associated downstream events, such as the activation of signal pathway proteins and inflammatory cytokine production, were down-regulated in the granulation tissues of postoperative mastoid cavity with otorrhea, possibly leading to endotoxin tolerance. Objective. The postoperative mastoid cavity is exposed to a high density and diversity of bacteria, but very little is known about how the immune environment is maintained in these regions with otorrhea. In this study, we investigated the changes in the TLR2 and TLR4 signaling pathways and inflammatory cytokine production in the granulation tissues of mastoid cavities with otorrhea and in normal auditory canal skin. Materials and methods. We investigated the expression of TLR2 and TLR4, as well as downstream signal pathway proteins, nuclear factor-κB (NF-κB) DNA binding, and secretion of tumor necrosis factor-α (TNF-α) in 28 samples of granulation tissue obtained from the postoperative mastoid cavity with otorrhea and 10 normal external auditory canal skin samples. Results. We found that the frequency of TLR2- and TLR4-positive cells was not increased in granulation tissues relative to normal skin, but the TLR4 mRNA and protein were down-regulated. In this pathophysiological process, there was also a lack of downstream signal pathway protein activation and secretion of TNF-α.

Expression of secretory leukocyte protease inhibitor in middle ear cholesteatoma

Secretory leukocyte protease inhibitor (SLPI) is a cationic protein and a member of the innate immunity-associated protein family. The main function of SLPI is to protect local tissue against the detrimental consequences of inflammation. We undertook this study to investigate the expression of SLPI in human middle ear cholesteatoma tissue as compared with normal external auditory canal skin. Cholesteatoma tissues and external auditory canal skin samples were obtained from eight patients during middle ear surgery. The expression levels of SLPI mRNA and protein were evaluated by real-time reverse transcription-polymerase chain reaction (RT-PCR) and western blotting. Immunohistochemical staining was performed in both tissue groups using anti-SLPI antibody. Real-time RT-PCR showed that SLPI mRNA levels in cholesteatoma tissues were increased 7.8-fold on average as compared with normal auditory canal skin. Western blotting analysis showed that SLPI protein expression in cholesteatoma epithelium is up-regulated versus external auditory canal skin epithelium. Immunohistochemical staining for SLPI showed that SLPI is expressed mainly in the stratum granulosum and in subepithelial inflammatory cells. These findings imply that SLPI contributes to host protection against inflammatory cell and destructive enzymes in the chronic inflammatory state of cholesteatoma by affecting the innate immune system.