BACKGROUND: Bronchopulmonary dysplasia (BPD) is a chronic lung disease driven by inflammation and oxidative stress. Mesenchymal stem cells (MSCs) have shown protective effects against hyperoxic lung injury. However, few studies have thoroughly examined the significantly differentially expressed genes (DEGs) in the lungs before and after MSC treatment. In this study, we analyzed the significant DEGs in lung tissues during both in vivo and vitro umbilical cord-derived mesenchymal stem cells (UCMSCs)-mediated repair of hyperoxic lung injury and investigated their potential mechanisms of action.
METHODS: Neonatal rats were exposed to hyperoxia and subsequently treated with UCMSCs. Inflammatory responses were quantified via ELISA and RT‒qPCR, while Western blotting (WB) and immunohistochemistry (IHC) were used to examine NLRP3 inflammasome and IL-1β expression. Transcriptomic analysis of UCMSC-mediated lung repair revealed 46 DEGs, which were validated by RT‒qPCR, and WB verified the significant differential expression of ALDH1A2. In RLE-6TN cells, Aldh1a2 expression was reduced during MSC-mediated repair of HO-induced oxidative stress injury. Functional evaluations were performed. WB further analyzed NLRP3 inflammasome and IL-1β expression in these processes. A recombinant adenoviral overexpression vector was intratracheally administered to hyperoxia-exposed neonatal rats. Arterial blood gas and RT‒qPCR were performed, and ELISA, WB, and IHC were used to evaluate the impact of Aldh1a2 overexpression on lung inflammation and oxidative stress, focusing on the NLRP3 inflammasome. 2 2
RESULTS: UCMSCs ameliorated hyperoxia-induced alveolar simplification and microvessel loss, reduced inflammation and oxidative stress injury, and inhibited the expression of the NLRP3 inflammasome. RT‒qPCR and WB analyses revealed significant differential expression of Aldh1a2 in UCMSC-treated hyperoxia-induced lung injury. UCMSCs also mitigated HO-induced oxidative stress injury in RLE-6TN cells. Inhibition of Aldh1a2 expression exacerbated oxidative stress, upregulated NLRP3 inflammasome and IL-1β expression, and impaired the reparative effects of UCMSCs. Conversely, Aldh1a2 overexpression or UCMSC intervention ameliorated hyperoxia-induced alveolar simplification and microvascular abnormalities, suppressed inflammation, and enhanced lung ventilation and angiogenesis. These findings indicated that Aldh1a2 overexpression inhibits NLRP3 inflammasome activation and IL-1β release. 2 2
CONCLUSIONS: Aldh1a2 was significantly differentially expressed in hyperoxic lung injury, with hyperoxia suppressing its expression and UCMSC treatment promoting its upregulation. Aldh1a2 mitigates lung inflammation and oxidative stress by inhibiting NLRP3 inflammasome activation.
