• Fang Song, Jinchao Hou, Zhecong Chen, Baoli Cheng, Ruyi Lei, Ping Cui, Yaqi Sun, Haihong Wang, and Xiangming Fang.
• From the Department of Anesthesiology and Intensive Care Unit, the First Affiliated Hospital (F.S., J.H., Z.C., B.C., R.L., P.C., Y.S., X.F.) Department of Anesthesiology and Intensive Care Unit, Sir Run Run Shaw Hospital (H.W.), School of Medicine, Zhejiang University, Hangzhou, China.
• Anesthesiology. 2018 Aug 1; 129 (2): 311-320.

What We Already Know About This TopicWHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Pyroptosis, a type of proinflammatory programmed cell death, drives cytokine storm. Caspase-11-dependent macrophage pyroptosis contributes to mortality during sepsis. Sphingosine-1-phosphate receptor 2 (S1PR2) signaling can amplify interleukin-1β secretion in endotoxin-induced inflammation. Here, we hypothesized that S1PR2 signaling increases caspase-11-dependent macrophage pyroptosis and worsens Gram-negative sepsis outcome.MethodsA Gram-negative sepsis model was induced through intraperitoneal injection of Escherichia coli. Primary peritoneal macrophages isolated from wild-type, S1pr2-deficient (S1pr2), or nucleotide-binding oligomerization domain-like receptor protein-3-deficient mice were treated with E. coli. Caspase-11 activation, macrophage pyroptosis, and Ras homolog gene family, member A-guanosine triphosphate levels were assessed in those cells. Additionally, monocyte caspase-4 (an analog of caspase-11) expression and its correlation with S1PR2 expression were determined in patients with Gram-negative sepsis (n = 11).ResultsGenetic deficiency of S1PR2 significantly improved survival rate (2/10 [20%] in wild-type vs. 7/10 [70%] in S1pr2, P = 0.004) and decreased peritoneal macrophage pyroptosis (pyroptosis rate: 35 ± 3% in wild-type vs. 10 ± 3% in S1pr2, P < 0.001). Decreased caspase-11 activation in S1PR2 deficiency cells contributed to the reduced macrophage pyroptosis. In addition, RhoA inhibitor abrogated the amplified caspase-11 activation in wild-type or S1PR2-overexpressing cells. In patients with Gram-negative sepsis, caspase-4 increased significantly in monocytes compared to nonseptic controls and was positively correlated with S1PR2 (r = 0.636, P = 0.035).ConclusionsS1PR2 deficiency decreased macrophage pyroptosis and improved survival in E. coli sepsis. These beneficial effects were attributed to the decreased caspase-11 activation of S1PR2-deficient macrophages. S1PR2 and caspase-11 may be promising new targets for treatment of sepsis.

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