# Biological and clinical evaluation of the laryngeal mucus layer

> **NIH NIH R21** · STANFORD UNIVERSITY · 2020 · $157,000

## Abstract

ABSTRACT
The vocal folds are exposed to ~25 million pollutant, viral, and bacterial insults each day and require protection
from this myriad of inhaled insults. Mucus is the thin layer of fluid that covers the surface of the vocal folds and
is the first line of defense in the larynx. However, an increased amount of thick, tacky mucus is commonly
observed on the vocal folds in persons with inflammatory voice disorders. This phenomenon, described as
“mucus aggregation,” is not trivial. Mucus aggregation is one of the most common complaints of persons with
voice disorders and leads to phonotraumatic behaviors, negatively impacts vocal fold vibration and voice
quality, and may even promote the accumulation of noxious irritants in the larynx. Currently, a major obstacle
in treating mucus aggregation is that biological mechanisms regulation laryngeal mucus production in normal
or inflamed larynges are not known. The overarching objective of this proposal is to elucidate cellular and
molecular mechanisms underlying laryngeal mucus production and to assess clinical mucus aggregation and
vocal function during normal and inflammatory conditions. The central hypothesis is that biological
mechanisms implicated in mucus overproduction and clinical features of mucus aggregation will be
appreciated in the inflammatory, but not normal condition. Cigarette smoke is a ubiquitous inhaled insult
implicated in the development of voice disorders and known to induce chronic airway inflammation.
Consequently, the first Specific Aim seeks to elucidate key biological and clinical properties of the laryngeal
mucus layer in nonsmokers (normal condition) and smokers (inflammatory condition). In Part A, we will
investigate cellular and molecular mechanisms implicated in mucus overproduction, including increased
quantity and altered quality of mucus. In Part B, we will assess clinical mucus aggregation on the vocal folds
and vocal function. The second Specific Aim will use a novel in vitro model system to measure the effect of
cigarette smoke on inflammatory cytokine concentration and laryngeal mucus production. This proposal is
innovative because it is the first to systematically elucidate biological mechanisms underlying the production of
the laryngeal mucus layer. We expect to identify cellular and molecular changes consistent with mucus
overproduction in an inflammatory, but not normal condition. This contribution, when integrated with concurrent
clinical mucus aggregation findings from vocal function assessment, is expected to be significant, as it will
provide insight into potential mechanisms underlying abnormal mucus aggregation on the vocal folds. These
findings will add to the knowledge base necessary in order to develop strategies to normalize the laryngeal
mucus layer. Such strategies will likely not only have a positive impact on voice production, but also overall
laryngeal health.

## Key facts

- **NIH application ID:** 9829094
- **Project number:** 5R21DC016126-03
- **Recipient organization:** STANFORD UNIVERSITY
- **Principal Investigator:** Elizabeth DiRenzo
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $157,000
- **Award type:** 5
- **Project period:** 2017-12-01 → 2020-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9829094

## Citation

> US National Institutes of Health, RePORTER application 9829094, Biological and clinical evaluation of the laryngeal mucus layer (5R21DC016126-03). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/9829094. Licensed CC0.

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