Sphingosine-1-phosphate Receptor 2 Signaling Promotes Caspase-11–dependent Macrophage Pyroptosis and Worsens Escherichia coli Sepsis Outcome

Abstract

What We Already Know about This Topic What 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. Methods A 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). Results Genetic 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). Conclusions S1PR2 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.

Rapamycin Inhibited Pyroptosis and Reduced the Release of IL-1β and IL-18 in the Septic Response

“…It is demonstrated that RAPA can reduce the pyroptosis in various cell models [ 18 – 20 ] and inhibition of pyroptosis prolong the survival of a sepsis animal model [ 4 , 9 – 11 ]. In the present study, we found that RAPA inhibited pyroptosis and reduced the septic response in both LPS-induced HUVECs and PMA+LPS-activated human THP-1 cell models of sepsis.…”

“…Studies show that pyroptosis is the trigger of the cytokine storm seen at the beginning of sepsis [4,8]. In addition, knockout of the gene encoding the pyroptotic protein Gasdermin D (GSDMD) and overexpression of autophagyrelated proteins can effectively inhibit pyroptosis and prolong the survival of a sepsis animal model [4,[9][10][11]. Kim et al found that microglial cells infected with Streptococcus pneumoniae overexpressed the autophagy-related proteins and exhibited low levels of pyroptosis, while inhibition of autophagy in the infected cells upregulated caspase-1 and increased IL-18 release [12].…”

“…Studies show that pyroptosis is the trigger of the cytokine storm seen at the beginning of sepsis [ 4 , 8 ]. In addition, knockout of the gene encoding the pyroptotic protein Gasdermin D (GSDMD) and overexpression of autophagy-related proteins can effectively inhibit pyroptosis and prolong the survival of a sepsis animal model [ 4 , 9 – 11 ].…”

Preconditioning with rHMGB1 ameliorates lung ischemia–reperfusion injury by inhibiting alveolar macrophage pyroptosis via the Keap1/Nrf2/HO-1 signaling pathway

“…To identify AM pyroptosis, gating was based on F4/80-positive cells, allowing analysis of fluorescently labeled active caspase-1 (FLICA) and propidium iodide. In this approach, F4/80 + FLICA + PI + cells appeared in the upper right quadrant of the FLICA-PI plot and were considered to be pyroptotic AMs [ 29 ]. Flow cytometry was conducted using an LSR2 flow cytometer (BD Biosciences), and raw data were analyzed using FlowJo software (TreeStar Corporation, USA).…”

Preconditioning with rHMGB1 ameliorates lung ischemia–reperfusion injury through inhibiting alveolar macrophages pyroptosis via Keap1/Nrf2/HO-1 signal pathway

“…Isotype control antibody (Immuno Chemistry Technology, USA) was used as negative control. FACS gating strategy for indicating macrophage pyroptosis was that F4/80 positive cells were gated to analyze uorescently labeled active caspase-1 (FLICA) and propidium iodide then F4/80+FLICA+PI+ cells were presented in the up-right region of FLICA-PI plot and indicated as AMs pyroptosis [29]. Flow cytometry analysis was conducted with a BD LSR2 ow cytometer (BD Biosciences).…”