Inflammatory mechanisms of dysbiosis in laryngeal glottic stenosis

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

PROJECT SUMMARY Acute laryngeal injury (ALgI) occurs in over 50% of patients after intubation and mechanical ventilation. ALgI is associated with significantly worse voice, breathing, and swallowing months after extubation. ALgI results from endotracheal tube pressure on the posterior glottis, leading to ischemic mucosal injury that progresses to glottic scar and debilitating phonatory insufficiency or life-threatening narrowing of the glottic airway. Glottic stenosis is managed with tracheostomy or destructive surgery sacrificing vocal quality for airway patency. There is a critical need for focused scientific approaches to identify key elements of pathologic wound healing following intubation-related laryngeal injury for the development of novel precision therapeutics. Studies of patients with post-intubation tracheal stenosis have implicated impaired epithelial barrier function, which leads to microbial infiltration into the tissue lamina propria, dysregulated adaptive immunity, and pathologic T-cell-fibroblast interactions that drive excessive extracellular matrix production. However, glottic stenosis is different, with severe functional implications of even minor scarring of the unique glottic anatomy. There is a significant knowledge gap regarding the pathophysiology of intubation-related glottic injury, and therefore a lack of evidence-based approaches to optimize wound healing to prevent scar. The PI has identified clinical bacterial culture positivity in 75% of human ALgI specimens, with Staph aureus most commonly isolated.1Persistent antigenic stimulation, such as in chronic infection, is known to induce sustained immune cell activation. The PI has measured increased T-cell infiltration and activation in patients with post-intubation tracheal stenosis, however the T-cell response following glottic injury is poorly characterized. Dysbiosis (imbalanced microbial composition) and its impact on the immune response have been linked to the progression of pulmonary fibrosis, however, a relationship among dysbiosis, immune activation and fibrosis has not been evaluated in glottic scar. In this study, we will determine the effect of dysbiosis-mediated immune activation on glottic scar formation in humans (Aim 1) and a novel murine model (Aims 2-3). In Aim 1 we will employ single-cell RNA sequencing and 16S rRNA sequencing to determine the impact of dysbiosis and immune activation on the formation of glottic scar in patients following laryngeal injury. In Aim 2, we will establish the role of microbiome- induced immune activation in the development of glottic scar by comparing laryngeal wound healing in germ- free and conventionally raised mice. Finally, in Aim 3 we will evaluate the impact of pathogenic bacteria and therapeutic microbiome modulation on the formation of glottic scar using the gnotobiotic mouse model.