Caspase-11–mediated endothelial pyroptosis underlies endotoxemia-induced lung injury
Kwong Tai Cheng, … , Jalees Rehman, Asrar B. Malik
Kwong Tai Cheng, … , Jalees Rehman, Asrar B. Malik
Published October 9, 2017
Citation Information: J Clin Invest. 2017;127(11):4124-4135. https://doi.org/10.1172/JCI94495.
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Research Article Pulmonology Vascular biology

Caspase-11–mediated endothelial pyroptosis underlies endotoxemia-induced lung injury

Abstract

Acute lung injury is a leading cause of death in bacterial sepsis due to the wholesale destruction of the lung endothelial barrier, which results in protein-rich lung edema, influx of proinflammatory leukocytes, and intractable hypoxemia. Pyroptosis is a form of programmed lytic cell death that is triggered by inflammatory caspases, but little is known about its role in EC death and acute lung injury. Here, we show that systemic exposure to the bacterial endotoxin lipopolysaccharide (LPS) causes severe endothelial pyroptosis that is mediated by the inflammatory caspases, human caspases 4/5 in human ECs, or the murine homolog caspase-11 in mice in vivo. In caspase-11–deficient mice, BM transplantation with WT hematopoietic cells did not abrogate endotoxemia-induced acute lung injury, indicating a central role for nonhematopoietic caspase-11 in endotoxemia. Additionally, conditional deletion of caspase-11 in ECs reduced endotoxemia-induced lung edema, neutrophil accumulation, and death. These results establish the requisite role of endothelial pyroptosis in endotoxemic tissue injury and suggest that endothelial inflammatory caspases are an important therapeutic target for acute lung injury.

Authors

Kwong Tai Cheng, Shiqin Xiong, Zhiming Ye, Zhigang Hong, Anke Di, Kit Man Tsang, Xiaopei Gao, Shejuan An, Manish Mittal, Stephen M. Vogel, Edward A. Miao, Jalees Rehman, Asrar B. Malik

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Figure 1

Intracellular LPS induces EC pyroptosis via activation of inflammatory caspases in mice and humans.

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Intracellular LPS induces EC pyroptosis via activation of inflammatory c...
(A) Flow cytometry histograms and (B) representative cytometry images of hMVECs transfected with 2 μg/ml FITC-labeled LPS (O111:B4) for 3 hours. LPS fluorescence in green and nuclear staining in red show that LPS crossed the EC plasma membrane. Scale bar: 20 μm. BF, bright field. (C) Time course of hMVEC intracellular FITC-LPS fluorescence in the presence of a transfection (T) reagent. Results are shown as mean ± SEM. n = 5. **P < 0.01 from baseline; ^P < 0.01 from previous group using ANOVA. (D) Phase-contrast micrographs of control hMVECs after a 16-hour period of LPS (2 μg/ml) incubation and after a 16-hour period of LPS transfection (2 μg/ml) show that LPS transfection, but not LPS incubation, induced lytic cell death. Scale bars: 100 μm. (E) Release of LDH showed that LPS incubation (2 μg/ml) for 16 hours or staurosporine-induced (STP-induced) apoptosis resulted in minimal LDH release, whereas LPS transfection (2 μg/ml) led to marked cell lysis. Cells were primed with an initial exposure to LPS (500 ng/ml for 3 hours). Cell lysis was blocked by the pan-caspase inhibitor Z-VAD-FMK or knockdown (KD) of the human inflammatory caspases 4 and 5 (Casp4/5). Results are shown as mean ± SEM. n = 5. ***P < 0.001 using ANOVA.