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Department of Medicine

Research

We inhale about 10,000 L of air to take oxygen into our bodies every day. Along with the inhaled air, numerous pathogens, chemical pollutants, and other irritants are inhaled, which could pose potential life-threatening risks to our lungs. However, our lungs are protected by mucociliary clearance (MCC), a critical innate defense mechanism that is important for maintaining lung health. The Okuda lab’s overall research interest focuses on how the MCC system is regulated to maintain homeostasis in the lung and how it fails in muco-obstructive lung diseases, including cystic fibrosis (CF), asthma, and COPD. Our previous work successfully characterized the regional expression patterns of major airway secretory mucins, MUC5AC/MUC5B, and CFTR/ionocytes in normal and CF human airways (Am J Respir Crit Care Med, 2019, 2021). These investigations provide insight into the small airway region (< 2 mm in diameter) as a critical site for pathogenesis of muco-obstructive lung diseases. We have developed a microdissection technique for human small airways and established in vitro and explant small airway epithelial cell cultures. We have combined these culture systems with single-cell-based omics approaches and gene editing technologies to understand cellular biology and physiology of the human small airways. In response to the emergent situation caused by the SARS-CoV-2 pandemic, the Okuda lab has also been actively involved in COVID-19 research.

MUC5AC, MUC5B, and CCSP mRNA co-expression is region-specific in normal human airways
MUC5AC, MUC5B, and CCSP mRNA co-expression is region-specific in normal human airways. Submucosal glands (SMG) express MUC5B, but not MUC5AC (A). Both MUC5B and MUC5AC are colocalized in CCSP+ cells in proximal superficial epithelium (B), whereas MUC5B is colocalized in CCSP+ cells of distal airway superficial epithelia (C). In the terminal bronchioles, neither MUC5B nor MUC5AC was detected (D). (Okuda et al, Am J Respir Crit Care Med, 2019).
CFTR expression in freshly excised normal human large and small airway epithelial cells by RNA-ISH
CFTR expression in freshly excised normal human large and small airway epithelial cells by RNA-ISH. RNA-ISH colocalizes CFTR in a FOXI1+ (ionocyte) cell in the large airway (arrow) and SCGB1A1+ (secretory) cells in the small airway (arrow heads), but not in FOXJ1+ (ciliated) cells in either region. Scale bars = 10 μm. (Okuda et al, Am J Respir Crit Care Med, 2021).
Epithelial Cell Cultures Figure
In vitro human large and small airway epithelial cell cultures. A. Large and small airway epithelial (LAE and SAE, respectively) cells were isolated, expanded, and then cultured in air-liquid interface (ALI) condition. B. H&E staining of well-differentiated in vitro LAE and SAE cells at ALI day 28. Scale bars = 10 μm. (C) Heat map displaying differentially expressed genes (adjusted P value < 0.01, Log FC ≧ 1 or ≦ -1) between in vitro LAE and SAE cells as determined by bulk RNA-seq. (Okuda et al, Am J Respir Crit Care Med, 2021).