Alterations in extracellular matrix composition in the aging larynx

Abstract

Objective: To study by immunohistochemistry the alterations of collagens I, III, IV, and V and elastin in the aging process of the human larynx.

Study design: Cadaver study.

Setting: Universidade Estadual Paulista, Botucatu Medical School, São Paulo State University (UNESP), Brazil.

Subjects and methods: Thirty vocal folds were obtained at autopsy from 10 adult men (aged 30 to 50 years) and 20 geriatric men (10 aged 60 to 75 years and 10 aged >75 years). Mid membranous vocal fold slides were subjected to immunohistochemical reactions. Digital imaging software (ImageJ) was used to quantify the increase in brownish staining of the lamina propria structures of vocal folds, from superficial to deep layers.

Results: There was an increase of collagen I and III immunoexpression in the elderly larynges, in both layers. Collagens IV and V were immunoexpressed in the vessels endothelium of the lamina propria and in the basement membrane. The immunoexpression of elastin decreased in the elderly larynges, in both lamina propria layers of the vocal folds.

Conclusion: A clear increase of collagens I and III and a decrease of elastic fibers were observed in the lamina propria of vocal folds. The concentration of collagens IV and V was the same across age groups. These findings suggest that as men age, the density of the extracellular matrix increases, brought about by an increase in collagen, while the loss of elastin results in decreased viscoelasticity.

Keywords: aged; collagen; elastin; immunohistochemistry; lamina propria; larynx; vocal folds.