Increased Expression of PD‐1 and PD‐L1 in Patients With Laryngotracheal Stenosis

Objectives Laryngotracheal stenosis (LTS) is a fibrotic condition of the upper airway. Recent evidence suggests dysregulated host immunity plays a role in LTS development and progression. The programmed death‐1 (PD‐1)/programmed death‐ligand 1 (PD‐L1) axis, targeted by paradigm‐shifting immunotherapies for cancer treatment, has also recently been implicated in the pathogenesis of fibrotic pulmonary disease. However, a role for the PD‐1/PD‐L1 axis in the proximal airway fibrosis seen in LTS patients has not been explored. Study Design Controlled ex vivo study. Methods Expression of PD‐1, PD‐L1, CD4, and CD8 were evaluated using immunohistochemical staining of cricotracheal resection specimens from postintubation iatrogenic laryngotracheal stenosis (iLTS), idiopathic subglottic stenosis (iSGS) patients, and normal controls derived from rapid autopsy (n = 8 per group). Fibroblasts derived from iLTS scar were also treated with transforming growth factor beta 1 (TGFβ1) and analyzed for PD‐L1 expression by quantitative real‐time polymerase chain reaction (n = 6). Results iLTS specimens exhibited increased expression of PD‐1, PD‐L1, and CD4 (all P