Cellular Adaptive Inflammation Mediates Airway Granulation in a Murine Model of Subglottic Stenosis

Objective. To determine the contribution of B- and T-cell-mediated inflammation in a murine airway granulation model. Study Design. Pilot study in a modified murine model. Setting. Philadelphia VA Medical Center Research Building. Subjects and Methods. Laryngotracheal complexes (LTCs) from 54 donor C57BL/6 mice were harvested and divided into 3 groups: (1) uninjured, (2) mechanically injured using a wire brush, and (3) chemically injured using hydrochloric acid. One donor LTC from each group was placed in deep dorsal subcutaneous pockets of either severe combined immunodeficiency (SCID)- or C57BL-recipient mice, for a total of 3 transplanted tracheas per recipient mouse. After 3 weeks, the transplanted LTCs were harvested from both C57BL- and SCID-recipient mice. Tissues were fixed, sectioned, and stained with hematoxylin and eosin. Representative slides were reviewed by a blinded pathologist to determine the formation of granulation tissue and graded as to the degree of formation of granulation tissue. Results. Despite significant granulation formation in C57BL-recipient mice, direct airway injury did not induce the formation of granulation tissue under the disrupted epithelium of airway mucosa in SCID mice 3 weeks after injury. Conclusion. The data indicate that the immune response that results in the formation of granulation tissue is mediated by circulating B-and/or T-cell processes rather than resident airway immune cells. Further studies focusing on cellular adaptive immune processes in response to airway injury may provide a novel treatment modality for subglottic stenosis.