Unique Cell Type–Specific Signaling Patterns Define Cholesteatoma

OBJECTIVE: To identify cell types and signaling pathways that drive cholesteatoma. METHODS: Single-cell RNA sequencing (scRNA-seq) was applied to identify differences between human cholesteatoma specimens and previously published scRNA-seq data for normal human tympanic membrane. The CellChat algorithm determined differential signaling pathways between both tissues. Cholesteatoma-specific markers were validated utilizing immunohistochemistry on human cholesteatoma specimens. BACKGROUND: Cholesteatoma is a complex, expansile, and destructive cystic epithelial lesion that occurs within the temporal bone. It destroys surrounding tissue, leading to significant otologic complications. Currently, the only treatment option is surgical removal of the disease, and despite surgical treatment, rates of recurrent or residual cholesteatoma following surgery approach 40% to 50% a decade later. Extensive research has attempted to generate medical treatments by delineating signaling pathways that drive cholesteatoma behavior, with numerous pathways identified. However, progress in developing pharmacologic treatment of cholesteatoma has been hampered by the inherent cellular heterogeneity, with cell type-specific behaviors obscured by bulk analysis of tissue. RESULTS: Cholesteatoma cellular composition differs notably from normal tympanic membrane, with increased numbers of immune cells in cholesteatoma. A number of cell signaling pathways are also differentially regulated between cholesteatoma and normal tissues, including several growth factors, Wnt, interleukin, cell adhesion, and tumor necrosis factor pathways, with unique cell type-specific patterns in cholesteatoma. CONCLUSIONS: scRNA-seq data define the cellular composition and cell type-specific signaling pathways in cholesteatoma, thereby identifying potential drug targets and informing future strategies to improve treatment of the disease. PROFESSIONAL PRACTICE GAP AND EDUCATIONAL NEED: The molecular understanding of cholesteatoma remains poor, resulting in a lack of medical treatments for this relatively common and troublesome condition. LEARNING OBJECTIVE: To define the cellular profile and cell type-specific signaling pathways of cholesteatoma relative to normal tympanic membrane. DESIRED RESULT: To define the unique cell type-specific signaling pathways within cholesteatoma that may warrant further evaluation as potential therapeutic targets for medical treatment of cholesteatoma. LEVEL OF EVIDENCE: Not applicable, in silico cellular study. INDICATE IRB OR IACUC: IRB HUM00153531.