Serum S100A8/A9 Correlates to Surgery-Free Interval in Idiopathic Subglottic Stenosis.

OBJECTIVE: Idiopathic subglottic stenosis (iSGS) is a progressive fibrotic condition of the subglottis that presents in women of northern European descent. Endoscopic dilation is a common surgical approach to management of iSGS. The surgery-free interval, or the time between endoscopic dilation procedures is considered an indicator of disease severity. Variations in surgery-free intervals among iSGS patients underscore the necessity for prognostic biomarkers. The objective of this study was to explore serum levels of the damage-associated molecular pattern S100A8/A9 as a prognostic biomarker in iSGS. METHODS: Serum from 20 iSGS patients and eight healthy controls was collected and S100A8/A9 levels were quantified using an ELISA. Patient data, including demographics and surgery-free intervals, were obtained from medical records. Serum S100A8/A9 levels were compared to surgery-free intervals. S100A8/A9 was also assessed using gene expression and immunofluorescence in iSGS specimens. RESULTS: S100A8/A9 was significantly elevated (p = 0.0413) in the serum of iSGS patients compared to controls (312.75 vs. 181.49 ng/mL). Linear regression analysis revealed a correlation (p = 0.009) between S100A8/A9 levels and endoscopic surgery-free interval. S100A8/A9 was significantly elevated (p = 0.0011) in patients with surgery-free intervals less than 1 year (455.2 ± 60.45 ng/mL; n = 8) compared to patients with intervals over 1 year (292.5.93 ± 162.4; n = 6). CONCLUSION: S100A8/A9 is increased in the serum and tissue of patients with iSGS. In this cohort of iSGS patients, serum S100A8/A9 was associated with surgery-free intervals, potentially representing a prognostic biomarker. Further research within a larger cohort is needed to confirm these findings. LEVEL OF EVIDENCE: 3 Laryngoscope, 135:1724-1731, 2025.