Figure 1

Hemoglobin RNA is expressed in human airway epithelium and increases during maturation to fully ciliated epithelium. (A) Box and whisker plots show hemoglobin β (Hbβ), hemoglobin α1 (Hbα1) and hemoglobin α2 (Hbα2) gene expression data (log2 transformed) of 48 samples collected from six healthy donors (GEO database¹¹: https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE97036). *p < 0.001. Box and whisker plots were created using R Software: R Core Team, 2021. R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL https://www.R-project.org/. (B) Reverse transcription polymerase chain reaction (RT-PCR) analysis of Hbβ expression normalized to actin levels in primary normal human airway epithelial cell ALI cultures at days 3, 10, and 35; mRNA Hbβ obtained from human blood was a control (n = 6, *p ≤ 0.0047). (C) SPRING plot from publicly available single cell gene cluster analysis of human bronchial epithelial cell ALI cultures¹². Each dot is a single cell. Blue-basal cells, purple-secretory, green-ionocytes, brown-brush + neuroendocrine cells, yellow-orange-ciliated cells. (D) Hbβ gene expression in primary human bronchial epithelial cells¹². Each dot is a single cell. The distribution of Hbβ in HBEC: Hbβ (green) is predominantly localized in ciliated cells; that is, it has the same distribution as the yellow-orange cells in (C). Arrow points to Hbβ in ciliated epithelium. The SPRING plot is queried for Hbβ (HBB) mRNA. (E) Hemoglobin α1 and α2 gene expression in primary human bronchial epithelial cells. There is less Hbα1 and Hbα2 (green) HBEC: Hbα1 (left, green) and Hbα2 (right, green), and they are not localized to ciliated cells. The SPRING plot is queried for Hbα1 and Hbα2 (HBA1 and HBA2) mRNA.