Abstract

Down Syndrome (DS), from trisomy 21 (T21), is the most common human chromosomal anomaly worldwide. Although DS can affect many organ systems, lung and heart disease are the leading causes of death. We recently reported that structural and molecular changes originate at the late pseudoglandular/early canalicular stages of development in T21 lungs. The initial, most striking, observation was dilatation of the terminal airways/acinar tubules. Thus, our goal was to better understand cellular heterogeneity at the transcriptional level that could be contributing to this phenotypic anomaly. Single cell RNA sequencing (scRNAseq) was used to generate transcriptomic profiles of individual human lung cells in tissue obtained from T21 (n=5) and non-T21 (n=4) prenatal lungs. Spatial differences in cellular phenotypes were examined using immunofluorescent staining (IF) and fluorescent in situ hybridization (FISH). Having previously observed structural changes in the airways, we focused the epithelial cell population. We noted differentially expressed genes within each epithelial sub-cluster between the T21 and non-T21 samples. Additionally, immunohistochemical staining showed a trend for an increase in the number of SCGB1A1 and FOXJ1 positive cells within the proximal airways of T21 lungs as compared to non-T21. Our sequencing data showed differentially increased SFTPC within the AT2 and distal bud populations, which was confirmed by FISH. Altogether, our data demonstrate that T21 is associated with increased expression of markers of differentiation in the prenatal lung, which may be an indication of accelerated epithelial cell differentiation.