RNA sequencing identifies transcriptional changes in the rabbit larynx in response to low humidity challenge

Taylor W Bailey,Jyothi Thimmapuram,M Preeti Sivasankar,Andrea Pires Dos Santos,Naila Cannes Do Nascimento,Shaojun Xie,Abigail Cox

doi:10.1186/s12864-020-07301-7

Taylor W Bailey, Jyothi Thimmapuram + Show 5 more

Open Access

https://doi.org/10.1186/s12864-020-07301-7

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Abstract

BackgroundVoice disorders are a worldwide problem impacting human health, particularly for occupational voice users. Avoidance of surface dehydration is commonly prescribed as a protective factor against the development of dysphonia. The available literature inconclusively supports this practice and a biological mechanism for how surface dehydration of the laryngeal tissue affects voice has not been described. In this study, we used an in vivo male New Zealand white rabbit model to elucidate biological changes based on gene expression within the vocal folds from surface dehydration. Surface dehydration was induced by exposure to low humidity air (18.6% + 4.3%) for 8 h. Exposure to moderate humidity (43.0% + 4.3%) served as the control condition. Ilumina-based RNA sequencing was performed and used for transcriptome analysis with validation by RT-qPCR.ResultsThere were 103 statistically significant differentially expressed genes identified through Cuffdiff with 61 genes meeting significance by both false discovery rate and fold change. Functional annotation enrichment and predicted protein interaction mapping showed enrichment of various loci, including cellular stress and inflammatory response, ciliary function, and keratinocyte development. Eight genes were selected for RT-qPCR validation. Matrix metalloproteinase 12 (MMP12) and macrophage cationic peptide 1 (MCP1) were significantly upregulated and an epithelial chloride channel protein (ECCP) was significantly downregulated after surface dehydration by RNA-Seq and RT-qPCR. Suprabasin (SPBN) and zinc activated cationic channel (ZACN) were marginally, but non-significantly down- and upregulated as evidenced by RT-qPCR, respectively.ConclusionsThe data together support the notion that surface dehydration induces physiological changes in the vocal folds and justifies targeted analysis to further explore the underlying biology of compensatory fluid/ion flux and inflammatory mediators in response to airway surface dehydration.

Highlights

Voice disorders are a worldwide problem impacting human health, for occupational voice users
Surface dehydration represents a loss of water from the mucosal surface of the larynx, and while some level of local tissue water loss may be experienced through compensatory rehydration of the epithelial surface, we would not expect systemic dehydration to result
We hypothesize that the homeostatic responses to surface and systemic dehydration are governed by different cellular mechanisms, we used % Packed cell volume (PCV) change to control for unintended systemic consequences of low humidity exposure with the concomitant withholding of food and water

Summary

Introduction

Voice disorders are a worldwide problem impacting human health, for occupational voice users. Voice disorders are a prevalent communication disorder affecting human health worldwide [1,2,3,4,5,6]. In the United States general population, the prevalence of voice disorders has been estimated at 6.2% [7], and more recently, at 7.6% [8]. The average associated health care costs in the United States have been estimated at almost 200 million dollars [14], and a study of Brazilian teachers having to take time away from work due to dysphonia illustrates the potential impact of a loss of productivity in the workforce [15].

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