Suppressing NF-κB and NKRF Pathways by Induced Pluripotent Stem Cell Therapy in Mice with Ventilator-Induced Lung Injury

Yung-Yang Liu,Kai-Hsi Lu,Li-Fu Li,Shih-Hwa Chiou,Chung-Chi Huang,Kuo-Chin Kao,Cheng-Ta Yang,Rajasingh Johnson

doi:10.1371/journal.pone.0066760

Abstract

BackgroundHigh-tidal-volume mechanical ventilation used in patients with acute lung injury (ALI) can induce the release of inflammatory cytokines, as macrophage inflammatory protein-2 (MIP-2), recruitment of neutrophils, and disruption of alveolar epithelial and endothelial barriers. Induced pluripotent stem cells (iPSCs) have been shown to improve ALI in mice, but the mechanisms regulating the interactions between mechanical ventilation and iPSCs are not fully elucidated. Nuclear factor kappa B (NF-κB) and NF-κB repressing factor (NKRF) have been proposed to modulate the neutrophil activation involved in ALI. Thus, we hypothesized intravenous injection of iPSCs or iPSC-derived conditioned medium (iPSC-CM) would decrease high-tidal-volume ventilation-induced neutrophil infiltration, oxidative stress, and MIP-2 production through NF-κB/NKRF pathways.MethodsMale C57BL/6 mice, aged between 6 and 8 weeks, weighing between 20 and 25 g, were exposed to high-tidal-volume (30 ml/kg) mechanical ventilation with room air for 1 to 4 h after 5×107 cells/kg mouse iPSCs or iPSC-CM administration. Nonventilated mice were used as control groups.ResultsHigh-tidal-volume mechanical ventilation induced the increases of integration of iPSCs into the injured lungs of mice, microvascular permeability, neutrophil infiltration, malondialdehyde, MIP-2 production, and NF-κB and NKRF activation. Lung injury indices including inflammation, lung edema, ultrastructure pathologic changes and functional gas exchange impairment induced by mechanical ventilation were attenuated with administration of iPSCs or iPSC-CM, which was mimicked by pharmacological inhibition of NF-κB activity with SN50 or NKRF expression with NKRF short interfering RNA.ConclusionsOur data suggest that iPSC-based therapy attenuates high-tidal-volume mechanical ventilation-induced lung injury, at least partly, through inhibition of NF-κB/NKRF pathways. Notably, the conditioned medium of iPSCs revealed beneficial effects equal to those of iPSCs.

Highlights

Acute lung injury (ALI) and its most severe manifestation, acute respiratory distress syndrome (ARDS) are marked by increased microvascular permeability and capillary leakage because of severe epithelial and endothelial injury [1,2]
The roles of Induced pluripotent stem cells (iPSCs) therapy in ventilator-induced lung injury (VILI) have not been fully delineated and require further exploration. In this high mechanical stretch-induced acute lung injury (ALI) model in mice, we examined the relationships between high VT ventilation, iPSCs and iPSC-derived conditioned medium production of macrophage inflammatory protein-2 (MIP-2), intracellular oxidative stress, and activation of Nuclear factor kappa B (NF-kB) and NF-kB repressing factor (NKRF) signaling using pharmacological inhibition with SN-50, a specific inhibitor for NF-kB and short interfering RNA targeted to NKRF
Histological examinations revealed that the animal lungs injured by mechanical ventilation at VT30 displayed a pattern of alveolar congestion, hemorrhaging, thickening of the alveolar wall, and neutrophil infiltration, which were largely rescued by the administration of iPSCs or iPSC-derived conditioned medium (iPSC-CM) (Figure 2A)

Summary

Introduction

Acute lung injury (ALI) and its most severe manifestation, acute respiratory distress syndrome (ARDS) are marked by increased microvascular permeability and capillary leakage because of severe epithelial and endothelial injury [1,2]. Mechanical ventilation with high tidal volumes (VT) causes ventilator-induced lung injury (VILI) characterized by noncardiogenic pulmonary edema, release of cytokines and chemokines leading to influx of neutrophils [3]. The recruitment of inflammatory cells with high VT ventilation is initiated by enhanced production of inflammatory mediators, such as murine macrophage inflammatory protein-2 (MIP-2), which is a functional homolog of human interleukin-8 (IL-8) in rodents. High-tidal-volume mechanical ventilation used in patients with acute lung injury (ALI) can induce the release of inflammatory cytokines, as macrophage inflammatory protein-2 (MIP-2), recruitment of neutrophils, and disruption of alveolar epithelial and endothelial barriers. We hypothesized intravenous injection of iPSCs or iPSC-derived conditioned medium (iPSC-CM) would decrease high-tidal-volume ventilation-induced neutrophil infiltration, oxidative stress, and MIP-2 production through NFkB/NKRF pathways

Methods

Results

Discussion

Conclusion