HSC Section 6 Nov2016 Green Book

Reprinted by permission of Otolaryngol Head Neck Surg. 2015; 152(2):302-307.

Original Research—Laryngology and Neurolaryngology

Otolaryngology– Head and Neck Surgery

Alterations in Extracellular Matrix Composition in the Aging Larynx

2015, Vol. 152(2) 302–307 ! American Academy of Otolaryngology—Head and Neck

Surgery Foundation 2014 Reprints and permission:

sagepub.com/journalsPermissions.nav DOI: 10.1177/0194599814562727 http://otojournal.org

Anete Branco, SLP, PhD 1 , Alexandre Todorovic Fabro, MD, PhD 2 , Tatiana Maria Gonc x alves, MD 1 , and Regina Helena Garcia Martins, MD, PhD 1

T he physiology of voice production is intimately con- nected with the characteristics of the vocal fold lamina propria, 1,2 the vocal fold being the main vibrating structure during phonation. 3 In the pursuit to understand the vocal properties typical of age groups, sexes, and diseases, researchers have gone deeper in their morphological studies, trying to elucidate the mechanisms involving the lamina pro- pria microstructures of vocal folds, mainly relating to elastic, collagen, and protein fibers. Collagen fibers are found across the whole lamina pro- pria, from its superficial to its deepest layers, 4,5 supporting tissue structure through enhanced stability and resistance, relevant to vocal physiology. Gray et al 6 confirmed that col- lagen and elastic fibers are involved in vocal fold biomecha- nics, in which the former allow tension and stretching while the latter allow deformation and a quick return to the initial shape. The composition of the vocal folds extracellular matrix varies significantly between sexes and age groups, implying biomechanical differences that directly influence the vocal properties. 7 The lamina propria trilaminar structure in the adult larynx described by Hirano 8 is not present in the new- born. 3,9,10 It starts to organize only in childhood, from 6 years of age onward. In aging people, anatomical and func- tional changes occur in the vocal tract, especially in the vocal folds. At this stage of life, structural and functional changes take place in the epithelial covering, the muscle, and the lamina propria of vocal folds, notably, the atrophy of epithelial layers and the vocal muscle, as well as density alterations in collagen and elastic fibers and in hyaluronic acid. 11-13 Elastic fibers change morphologically in elderly people, relative to adults. Their remodeling with age is reflected by 1 Ophthalmology, Otorhinolaryngology, Head and Neck Surgery Depart- ment, Botucatu Medical School, UNESP–Univ Estadual Paulista, Sa˜o Paulo, Brazil 2 Department of Pathology, Botucatu Medical School, UNESP–Univ Estadual Paulista, Sa˜o Paulo, Brazil Corresponding Author: Regina Helena Garcia Martins, SLP, PhD, Botucatu Medical School/UNESP, Ophthalmology, Otorhinolaryngology, Head and Neck Surgery Department, Distrito de Rubia˜o Jr, CEP 18618-970, Botucatu, Sa˜o Paulo, Brazil. Email: rmartins@fmb.unesp.br

Sponsorships or competing interests that may be relevant to content are dis- closed at the end of this article.

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, Sa˜o 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 stain- ing of the lamina propria structures of vocal folds, from superficial to deep layers. Results. There was an increase of collagen I and III immu- noexpression 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 pro- pria 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 collagen, elastin, aged, lamina propria, vocal folds, larynx, immunohistochemistry

Received May 15, 2014; revised October 28, 2014; accepted November 14, 2014.

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