Molecular Characterization of Hypoxic Alveolar Epithelial Cells After Lung Contusion Indicates an Important Role for HIF-1α. Issue 2 (February 2018)

• Record Type: Journal Article
• Authors: Sherman, Matthew A.; Suresh, Madathilparambil V.; Dolgachev, Vladislav A.; McCandless, Lane K.; Xue, Xiang; Ziru, Li; Machado-Aranda, David; Shah, Yatrik M.; Raghavendran, Krishnan
• Is Part Of: Annals of surgery. Volume 267:Issue 2(2018:Feb.)
• Publication Date: 2018-02
• Subjects: alveolar epithelial cells -- hypoxia -- LCM -- lung contusion; Surgery -- Periodicals; 617.005
• DOI: 10.1097/SLA.0000000000002070
• Languages: English
• ISSNs: 0003-4932

Abstract

Abstract : Objective: To understand the fate and regulation of hypoxic type II alveolar epithelial cells (AECs) after lung contusion (LC). Background: LC due to thoracic trauma is a major risk factor for the development of acute respiratory distress syndrome. AECs have recently been implicated as a primary driver of inflammation in LC. The main pathological consequence of LC is hypoxia, and a key mediator of adaptation to hypoxia is hypoxia-inducible factor (HIF)-1. We have recently published that HIF-1α is a major driver of acute inflammation after LC through type II AEC. Methods: LC was induced in wild-type mice (C57BL/6), luciferase-based hypoxia reporter mice ( ODD-Luc ), and HIF-1α conditional knockout mice. The degree of hypoxia was assessed using hypoxyprobe and in vivo imaging system. The fate of hypoxic AEC was evaluated by luciferase dual staining with caspases-3 and Ki-67, terminal deoxynucleotidyl transferase dUTP nick end labeling, and flow cytometry with ApoStat. NLRP-3 expression was determined by western blot. Laser capture microdissection was used to isolate AECs in vivo, and collected RNA was analyzed by Q-PCR for HIF-related pathways. Results: Global hypoxia was present after LC, but hypoxic foci were not uniform. Hypoxic AECs preferentially undergo apoptosis. There were significant reductions in NLRP-3 in HIF-1α conditional knockout mice. The expression of proteins involved in HIF-related pathways and inflammasome activation were significantly increased in hypoxic AECs. Conclusions: These are the first in vivo data to identify, isolate, and characterize hypoxic AECs. HIF-1α regulation through hypoxic AECs is critical to the initiation of acute inflammation after LC.