Zinc deficiency primes the lung for ventilator-induced injury
Francis Boudreault ... Daniel J. Tschumperlin, Rebecca M. Baron
Francis Boudreault ... Daniel J. Tschumperlin, Rebecca M. Baron
Published June 2, 2017
Citation Information: JCI Insight. 2017;2(11):e86507. doi:10.1172/jci.insight.86507.
View: Text | PDF
Categories: Research Article Inflammation Pulmonology

Zinc deficiency primes the lung for ventilator-induced injury

Abstract

Mechanical ventilation is necessary to support patients with acute lung injury, but also exacerbates injury through mechanical stress–activated signaling pathways. We show that stretch applied to cultured human cells, and to mouse lungs in vivo, induces robust expression of metallothionein, a potent antioxidant and cytoprotective molecule critical for cellular zinc homeostasis. Furthermore, genetic deficiency of murine metallothionein genes exacerbated lung injury caused by high tidal volume mechanical ventilation, identifying an adaptive role for these genes in limiting lung injury. Stretch induction of metallothionein required zinc and the zinc-binding transcription factor MTF1. We further show that mouse dietary zinc deficiency potentiates ventilator-induced lung injury, and that plasma zinc levels are significantly reduced in human patients who go on to develop acute respiratory distress syndrome (ARDS) compared with healthy and non-ARDS intensive care unit (ICU) controls, as well as with other ICU patients without ARDS. Taken together, our findings identify a potentially novel adaptive response of the lung to stretch and a critical role for zinc in defining the lung’s tolerance for mechanical ventilation. These results demonstrate that failure of stretch-adaptive responses play an important role in exacerbating mechanical ventilator–induced lung injury, and identify zinc and metallothionein as targets for lung-protective interventions in patients requiring mechanical ventilation.

Authors

Francis Boudreault, Miguel Pinilla-Vera, Joshua A. Englert, Alvin T. Kho, Colleen Isabelle, Antonio J. Arciniegas, Diana Barragan-Bradford, Carolina Quintana, Diana Amador-Munoz, Jiazhen Guan, Kyoung Moo Choi, MICU Registry, Lynette Sholl, Shelley Hurwitz, Daniel J. Tschumperlin, Rebecca M. Baron

×
Options: View larger image (or click on image)
Metallothionein (MT) genes are highly responsive to stretch. (A) CCL-151...

Figure 1

Metallothionein (MT) genes are highly responsive to stretch.

(A) CCL-151, CCL-153, A549, and 16HBE14o- cells were exposed to tonic stretch (30% strain) for 4 hours, and then replicate analysis (validating the microarray analysis in Tables 1 and 2) of stretch-induced expression by real-time quantitative PCR (qPCR) for MT1G, MT1M, and MT1X transcript levels (n = 3) expressed relative to time-matched controls (n = 3) was performed. (B) CCL-151 cells were tonically stretched (30% strain) for the indicated periods of time before RNA harvest and gene expression analysis by qPCR. An independent 6-well BioFlex plate was used for each time point (n = 3 stretched and 3 control wells per time point). *P < 0.05 versus unstretched control for all 3 genes by Kruskal-Wallis test with Dunn’s multiple comparison’s test. (C) CCL-151 cells were exposed to tonic stretch with amplitudes of 10%, 20%, and 40% strain and assessed for transcript level changes after 4 hours. Each strain increment was measured from an independent 6-well BioFlex plate (n = 3 stretched and 3 control wells per increment of strain). *P < 0.05 versus unstretched control for MT1G by Kruskal-Wallis test with Dunn’s multiple comparisons test. (D) HMVEC-L cells and (E) CCL-151 fibroblasts were cyclically stretched 20% (sinusoidal waveform) at 0.33 Hz for 4 hours and probed for MT transcript levels by qPCR (n = 3 stretched and 3 time-matched controls for endothelial cells and n = 5 stretched and 5 time-matched controls for fibroblasts). *P < 0.05 versus control, Student’s 2-tailed t test. (F) CCL-151 cells subjected to cyclical stretch as in panel E or unstretched control cells (pooled from 3 separate wells) were harvested for protein and analyzed by Western blotting using MT and β-actin (loading control) antibodies. As a control to confirm specificity of the MT antibody, lungs harvested from WT and MT knockout (KO) mice subjected to ventilator-induced lung injury (VILI) for 4 hours with 24 ml/kg tidal volume, as described in more detail in Figure 2, were analyzed by Western blotting using the same antibodies.