ASM-Ceramide Axis Modulation Is Associated With TSLP Release and Epithelial Barrier Dysfunction in an In Vitro Type 2...

Epithelial barrier dysfunction is an early feature of pediatric rhinitis, but the upstream epithelial events that initiate this process remain incompletely defined. Because lipid remodeling and epithelial-derived alarmins may interact during type 2 inflammation, this study examined whether acid sphingomyelinase (ASM)-ceramide signaling is associated with thymic stromal lymphopoietin (TSLP) release and barrier impairment in a pediatric rhinitis-related nasal epithelial model.

Primary human nasal epithelial cells were stimulated with interleukin-4 (IL-4)/interleukin-13 (IL-13) (10 ng/mL each, 24 h) to model a type 2 inflammatory epithelial milieu. ARC39 was used to inhibit ASM, and siRNA was used to knock down TSLP. TSLP was quantified by enzyme-linked immunosorbent assay (ELISA); barrier function was assessed by FITC-dextran permeability and ZO-1 immunofluorescence; ceramide levels were measured using a commercial kit; and sphingomyelin phosphodiesterase 1 (SMPD1) expression was evaluated by quantitative real-time PCR (qRT-PCR) and Western blotting.

IL-4/IL-13 stimulation increased TSLP release and impaired epithelial barrier integrity (P < 0.001). ARC39 reduced ceramide levels and decreased TSLP output (P < 0.001) in a concentration-dependent manner, with an evident effect at approximately 5 µM, whereas SMPD1 expression remained largely unchanged. TSLP knockdown improved barrier function indicators (P < 0.05), and combined ARC39 treatment did not produce an additional effect beyond TSLP knockdown.

ASM-ceramide axis modulation was associated with TSLP release and epithelial barrier dysfunction in this in vitro model. These findings suggest a possible link among sphingolipid remodeling, epithelial alarmin responses, and barrier injury, but further mechanistic and clinical validation is needed.