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 2

TLR4-mediated LPS signaling is required for activation of endothelial pyroptosis.

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TLR4-mediated LPS signaling is required for activation of endothelial py...
Immunoblot analysis of the inflammatory caspase-11 in mMVECs (A) and the inflammatory caspases 4 and 5 in hMVECs (B) in the presence or absence of priming with extracellular 500 ng/ml LPS for 3 hours prior to transfecting the cells with 2 μg/ml LPS for 16 hours. (C) Quantification of the inflammatory caspase expression shows significant upregulation of caspases 4 and 5 in human ECs and caspase-11 in mouse ECs with priming. Statistics obtained from Student’s 2-tailed t test. (D) hMVECs were first primed with extracellular (E) LPS or PBS, then transfected (T) with LPS or only incubated (I) with extracellular LPS. (E) Dose dependence of EC lysis in hMVECs induced by intracellular LPS. (F) LDH release by mMVEC isolated from WT, Tlr4–/–, and Casp11–/– mice after internalization of LPS for 16 hours. CTRL, control. (G) Western blot and (H) ELISA detection of mature IL-1β in hMVEC lysates and culture supernatants 16 hours after endothelial transfection with LPS (2 μg/ml) or without LPS transfection. (H) There was a significant amount of mature IL-1β release when ECs were primed with extracellular LPS and subsequently exposed to intracellular LPS for 16 hours. Results are shown as mean ± SEM. n ≥ = 5. *P < 0.05; ***P < 0.001. All statistics except C obtained from ANOVA.