Consecutive Hypoxia Decreases Expression of NOTCH3, HEY1, CC10, and FOXJ1 via NKX2-1 Downregulation and Intermittent Hypoxia-Reoxygenation Increases Expression of BMP4, NOTCH1, MKI67, OCT4, and MUC5AC via HIF1A Upregulation in Human Bronchial Epithelial Cells

Abstract

Previous studies have shown that the experimental models of hypoxia-reoxygenation (H/R) mimics the physiological conditions of ischemia-reperfusion and induce oxidative stress and injury in various types of organs, tissues, and cells, both in vivo and in vitro, including human lung adenocarcinoma epithelial cells. Nonetheless, it had not been reported whether H/R affected proliferation, apoptosis, and expression of stem/progenitor cell markers in the bronchial epithelial cells. In this study, we investigated differential effects of consecutive hypoxia and intermittent 24/24-h cycles of H/R on human bronchial epithelial (HBE) cells derived from the same-race and agematched healthy subjects (i.e., NHBE) and subjects with chronic obstructive pulmonary disease (COPD) (i.e., DHBE). To analyze gene/protein expression during differentiation, both the NHBE and DHBE cells at the 2nd passage were cultured at the air-liquid interface (ALI) in the differentiation medium under normoxia for 3 days, followed by either culturing under hypoxia (1% O 2) for consecutively 9 days and then returning to normoxia for another 9 days, or culturing under 24/24-h cycles of H/R (i.e., 24 h of 1% O 2 followed by 24 h of 21% O 2 , repetitively) for 18 days in total, so that all differentiating HBE cells were exposed to hypoxia for a total of 9 days. In both the normal and diseased HBE cells, intermittent H/R significantly increased HIF1A, BMP4, NOTCH1, MKI67, OCT4, and MUC5AC expression, while consecutive hypoxia significantly decreased NKX2-1, NOTCH3, HEY1, CC10, and FOXJ1 expression.

Targeting Interleukin-10 Restores Graft Microvascular Supply and Airway Epithelium in Rejecting Allografts

“…Moreover, preclinical and clinical lung transplantation studies also demonstrated that Tregs and their associated mediators modulate both airway epithelium and vascular endothelium of grafted tissue, which effectively modulates the expression of various adhesion proteins on the surface of both airway epithelium and microvessels within the graft [22][23][24][25][26][27][28][29][30][31]. Inflammation-associated airway epithelial, ciliary loss, and vascular endothelial injury have been reported in various preclinical and clinical transplantation studies [22,23,[32][33][34]. FOXJ1 has been associated with ciliogenesis in airway epithelium and affected largely due to the severe hypoxic and ischemic state of the tissue [34].…”

“…Inflammation-associated airway epithelial, ciliary loss, and vascular endothelial injury have been reported in various preclinical and clinical transplantation studies [22,23,[32][33][34]. FOXJ1 has been associated with ciliogenesis in airway epithelium and affected largely due to the severe hypoxic and ischemic state of the tissue [34]. β-Catenin plays a vital role in cell survival and proliferation; however, little is known regarding its role in endothelial cells.…”

Hypoxic conditions promote a proliferative, poorly differentiated, and pro-secretory phenotype in COPD lung tissue progenitor cells in vitro

“…Similarly cell-line models have also demonstrated increased oxidative stress, increased pro-inflammatory mediators, reduced anti-inflammatory mediators and reduced surfactant proteins 10 . Many effects of hypoxia can be induced both via continuous hypoxia or by hypoxia/reoxygenation events 12,11,10 , both of which can be found in COPD patients.…”

“…Despite this there is a scarcity of data regarding the direct impacts of hypoxia on lung cellular behaviour. The limited evidence available has shown a number of effects including increased oxidative stress, inflammatory markers, and pro-apoptotic genes in animal models [10][11][12] . Similarly cellline models have also demonstrated increased oxidative stress, increased pro-inflammatory mediators, reduced anti-inflammatory mediators and reduced surfactant proteins 10 .…”

“…The limited evidence available has shown a number of effects including increased oxidative stress, inflammatory markers, and pro-apoptotic genes in animal models [10][11][12] . Similarly cellline models have also demonstrated increased oxidative stress, increased pro-inflammatory mediators, reduced anti-inflammatory mediators and reduced surfactant proteins 10 . Many effects of hypoxia can be induced both via continuous hypoxia or by hypoxia/reoxygenation events 12,11,10 , both of which can be found in COPD patients.…”