Ciliogenesis defects in human trisomy 21 lungs resulting from IFN-I hyperactivation

Background: Children with Trisomy 21 (T21) experience high rates of respiratory disease, but the developmental origins of airway epithelial defects remain poorly defined. Airway integrity relies on balanced differentiation of basal, secretory, and ciliated cells, as well as intact tight junctions, which can result in mucociliary clearance issues, a phenomenon observed in T21. Since T21 is characterized by chronic type I interferon (IFN-I) hyperactivation, we investigated whether airway abnormalities arise in utero and whether IFN signaling contributes to these defects. Methods: Human prenatal and postnatal non-T21 and T21 lungs were analyzed by FISH, immunofluorescence (IF), and RT-qPCR to quantify epithelial cell populations and IFN-I pathway activation. Basal cells were isolated from prenatal large airways from matched samples and were cultured in air-liquid interface (ALI) to assess differentiation, ciliary function (ciliary beat frequency (CBF)), and barrier integrity (TEER, ZO-1 staining, and TEM). Non-T21 ALI cultures were treated with IFN-β (400 pg/mL) for 21 days to model T21-associated IFN-I signaling. Membranes were collected for gene and protein analysis. Results: In prenatal and postnatal T21 lungs, RT-qPCR and FISH demonstrated elevated IFN-I pathway activity, with increased MX1, IFI27, IFNAR1/IFNAR2, and IFNB1 expression compared to non-T21 lungs (p< 0.01). In prenatal T21 lungs, IF and RT-qPCR showed a trend toward reduced basal cells (TP63) and a significant expansion of secretory cells (SCGB1A1/SCGB3A2; p< 0.05), while ciliated cell numbers (FOXJ1) were unchanged. Postnatally, secretory cell expansion persisted (p< 0.05), but ciliated cells were significantly decreased, with fewer FOXJ1+/ARL13B+ cells and reduced FOXJ1 transcript levels (p< 0.05). Moreover, tight junctions were compromised in T21 prenatal airways, with disorganized ZO-1, abnormal tight junction ultrastructure, and a trend toward decreased OCLN expression (p< 0.05). In vitro, T21 ALI cultures from prenatal basal cells recapitulated the postnatal tissue phenotype, with increased secretory cells, reduced ciliated cells and CBF, and disrupted ZO-1 organization compared to non-T21 ALI (p< 0.05). IFN-β treated non-T21 ALI cultures showed an increase in secretory cell differentiation (SCGB1A1), impaired ciliated cell formation (FOXJ1+/ARL13B+), and ciliary dysfunction comparable to T21 ALI, with significantly reduced CBF relative to untreated controls as well as disrupted tight junction (p< 0.05). Conclusion: Airway epithelial dysregulation in T21 begins in utero, with a possible shift from basal toward secretory fates, disrupted tight junctions, and postnatal loss of ciliated cells. These defects are reproduced in T21 ALI cultures and can be recapitulated by chronic IFN-β exposure. This indicates that IFN-I hyperactivation is a central driver of abnormal airway epithelial differentiation and impaired ciliary function in T21, identifying IFN-I signaling as a potential therapeutic target for early-onset airway disease in Trisomy 21. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.