Immunohistochemical Localization of D-<i>β</i>-Aspartic Acid and Periostin in Vocal Fold Polyps

Long-term voice abuse or sudden vocal fold microvascular disruption may lead to injury and subsequent repair/remodeling in the vocal fold mucosa. Periostin is known to be involved in airway remodeling and also in various otolaryngological diseases. D-β-aspartic acid is the major isomer of D-aspartic acid found in elderly tissue. In this study we investigated the expression and the role of D-β-aspartic acid and periostin in the formation of vocal fold polyps. The expression patterns of D-β-aspartic acid and periostin in 36 surgical specimens of vocal fold polyps from 36 patients were investigated immunohistochemically. In the epithelium of vocal polyps, D-β-aspartic acid was expressed in all cases. Expression of D-β-aspartic acid was detected in 25 samples obtained from patients with vocal fold polyps stroma. Expression of periostin was detected in 28 samples obtained from patients with vocal fold polyps. Two patterns of D-β-aspartic acid expression were observed in vocal fold polyps stroma: positive type and negative type. The following four patterns of periostin expression were observed in vocal fold polyps: negative type, superficial type, infiltrative type, and diffuse type. An association was observed between D-β-aspartic acid expression patterns and periostin expression patterns. From these findings we speculate that periostin and D-β-aspartic acid participate in certain pathological changes in vocal fold polyps, such as extracellular matrix accumulation, local fibrosis, and the formation and development of vocal fold polyps.