Localized Knockout of E-Cadherin in Subglottic Mucosa Increases Fibrosis

Introduction: Recent advancements have implicated a dysfunctional epithelial barrier and reduced tight junction protein expression, including E-cadherin, in the pathogenesis of idiopathic subglottic stenosis (iSGS), but confirmatory knockout studies are lacking.

Methods: Mice with loxP sites flanking E-cadherin underwent extra-tracheal placement of a fibrin-plasmin gel embedded with either Cre-expressing or control adenovirus. Mice then underwent chemo-mechanical injury to induce laryngotracheal stenosis, with harvest of subglottis/tracheas 21 days later. Kaplan-Meier survival curves, lamina propria thickness on H&E histology, and fibrotic gene expression (COL1, COL3, COL5, and FN1) were compared between experimental and control mice.

Results: Immunofluorescence and Western blotting confirmed decreased E-cadherin expression in experimental mice. On H&E, lamina propria thickness was greater in E-cadherin knockout mice. Survival was significantly shorter for knockout mice relative to control (median survival ratio [95% CI], 0.6 [0.3 – 0.9]; p = 0.01). Further, fibrotic gene expression of COL1 (median fold-change [95% CI], 15.7 [3.0 – 63.3]; p = 0.03), COL3 (38.0 [17.1 – 61.9]; p = 0.03), COL5 (8.0 [4.3 – 16.7]; p=0.03), and FN1 (9.1 [2.6 – 39.9]; p = 0.03) was significantly greater relative to control.

Conclusions: Localized subglottic knockout of E-cadherin in a floxed murine model results in greater fibrosis and reduced mortality, further supporting the role of epithelial barrier dysfunction in the pathogenesis of iSGS. Therapies that restore epithelial integrity may therefore represent a rationale pharmacologic target.