Revealing concealed cardioprotection by platelet Mfsd2b-released S1P in human and murine myocardial infarction

Figures

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  Fig. 1. Supernatant of activated platelets reduces infarct size and improves cardiac outcome after myocardial infarction—this depends on platelet sphingosine kinase 1. a Injection of cell-free supernatant of activated platelets (SNT+) prior AMI leads to decreased infarct size (INF/AAR) after 24 h of reperfusion as compared to supernatant of non-activated platelets (SNT−) and NaCl (ANOVA-analysis, nNaCl = 10, nSNT− = 13, nSNT+ = 13). b Area at risk per left ventricle (AAR/LV) did not differ between the groups. c Echocardiographic assessment 24 h post AMI showed improved cardiac function (EF = ejection fraction) in SNT+ treated mice (ANOVA-analysis, nNaCl = 10, nSNT− = 13, nSNT+ = 13). d Exemplary images of TTC-stained hearts. e This reduction of infarct size by SNT+ was associated with reduced neutrophil accumulation 24 h after AMI (unpaired t test, nSNT− = 7, nSNT+ = 8, scale bar left: 100 µm, scale bar right: 30 µm). f Apoptosis was reduced five days after AMI (unpaired t test, nSNT− = 7, nSNT+ = 7, scale bar left: 100 µm, scale bar right: 30 µm), and g–j cardiac function was improved 21 days after AMI (SV = stroke volume, CO = cardiac output, HR = heart rate, unpaired t test, nSNT− =…

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  Fig. 2. Platelet-derived S1P exerts cardioprotection through the cardiomyocyte S1P receptor 1 (S1P1) and deficiency of platelet S1P transporter major facilitator superfamily domain containing 2B (Mfsd2b) leads to increased infarct size in vivo. a SNT+ leads to decreased infarct size (IS [%LV]), b higher left ventricular pressure gradient (DP), and c lower left ventricular end-diastolic pressure (LVEDP) in a model of Langendorff-perfused hearts. This was blunted by pharmacological inhibition of S1P receptor 1 via W146 treatment (S1P1; two-way ANOVA, Vehicle nSNT− = 10, nSNT+ = 8, W146 nSNT− = 7, nSNT+ = 5). d Accordingly, genetic cardiomyocyte deficiency of S1P1 (S1P1αMHCCre−) abrogated beneficial SNT+ effects in Langendorff-perfused hearts in terms of infarct size, e left ventricular pressure gradient (DP) and f LVEDP (two-way ANOVA, S1P1αMHCCre− nSNT− = 6, nSNT+ = 5, S1P1αMHCCre+ nSNT− = 6, nSNT+ = 5). g In vivo AMI experiments in these animals revealed preserved cardioprotection in littermate controls but blunted reduction of infarct size (INF/AAR) in cardiomyocyte-specific S1P1 deficiency (Two-way ANOVA, S1P1αMHCCre− nSNT− = 14, nSNT+ = 14, S1P1αMHCCre+ nSNT− = 9, nSNT+ = 11). h No…

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  Fig. 3. S1P concentrations are associated with outcome of patients with STEMI - inhibition of platelet aggregation by GPIIb/IIIa but not P2Y12 antagonists preserves platelet S1P release and cardioprotection. a Platelet S1P release during activation was reduced by P2Y12 inhibition (Can=Cangrelor) but preserved during GPIIb/IIIa inhibition (Tiro=Tirofiban, ANOVA-analysis, n = 9). b, c This translated to blunted cardioprotection by activated platelet supernatant (SNT+) of cangrelor-treated platelets but sustained cardioprotection during tirofiban treatment (ANOVA-analysis, n = 8). d As expected platelet aggregation was sufficiently inhibited by both cangrelor and tirofiban (maximum of aggregation (MoA), ANOVA-analysis, nVehicle = 6, nCan = 6, nTiro = 6). e, f In contrast, alpha-granule (e) and dense-granule (f) release were not affected by tirofiban (ANOVA-analysis nVehicle = 6, nCan = 6, nTiro = 6). g Plasma S1P concentrations were associated with cardiovascular death and h infarct size in patients with ST-elevation myocardial infarction (Pearson correlation, n = 38). Error bars in each panel represent standard deviation.

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  Fig. 4. Main findings of this study. Activated platelets release S1P during acute myocardial infarction (AMI) through the S1P exporter Mfsd2b; platelet-derived S1P during AMI is cardioprotective by engaging the cardiomyocyte S1P1; platelet S1P-mediated cardioprotection is preserved with GPIIb/IIIa antagonists, but not P2Y12 antagonists. The Figure was partly generated using Servier Medical Art, provided by Servier, licensed under a Creative Commons Attribution 3.0 unported license (https://creativecommons.org/licenses/by/3.0/).