Fig 1.
In vivo HDL protects the heart from IR injury via STAT3 activation.
Mice were submitted to LAD occlusion for 45min and hearts were reperfused for 24h. Mice were injected or not (IR) with HDL (HDL) one minute before reperfusion. A) Quantification of infarct size (I) expressed in % of area at risk (AAR). B) Quantification of AAR per ventricle surface (V). C) Representative images of TTC stained middle heart sections of control or treated mice. Data are mean ± SEM, n = 6–8, *: p<0.05 vs IR.
Fig 2.
In vivo HDL regulates specific miRNAs during IR injury.
Mice were sham operated (sham) or submitted to LAD occlusion for 45min and hearts were reperfused for 8h (IR). HDL was injected or not one min before reperfusion. miRNA was isolated from total heart and miRNA expression assessed by microarray analysis after 8h of reperfusion in in vivo mouse hearts using GeneChip miRNA 2.0 Arrays. A) miRNA expression significant change (p<0.05) between sham and IR group (Heatmap representation). B) Expression of miR-34b and miR-337 (boxplot representation). n = 3. *: p<0.05 vs sham, #: p<0.05 vs IR.
Fig 3.
In vivo HDL regulates miR-34b and miR-337 during IR injury.
Mice were sham operated (sham) or submitted to LAD occlusion for 45min and hearts were reperfused for 8h (IR). HDL was injected or not one min before reperfusion. miRNA was isolated from total heart. A) miR-34b and B) miR-337 expression was measured by qPCR and normalized to U6 expression. Data are mean ± SEM, n = 6–9, *: p<0.05 vs sham, #: p<0.05 vs hypoxia. The difference between sham STAT3-WT and STAT3-KO is significant (p<0.05).
Fig 4.
HDL improves cell survival against hypoxia and regulates specific miRNAs during hypoxia.
Cardiomyocytes were incubated in Tyrode solution, submitted to 7h hypoxia and treated during hypoxia with HDL. A) Cell viability, B) miR-34b and C) miR-337 expression. Results are expressed in percentage of normoxia. Data are mean ± SEM, n = 8–10, *: p<0.05 vs normoxia, #: p<0.05 vs hypoxia.
Fig 5.
HDL improves cell survival against hypoxia via STAT3 and miRNA expression.
Cardiomyocytes transfected with control or STAT3 siRNA were incubated in Tyrode solution, submitted to 7h hypoxia and treated during hypoxia with HDL. A) Cell viability, B) miR-34b and C) miR-337 expression. Results are expressed in percentage of normoxia. Data are mean ± SEM, n = 3–7, *: p<0.05 vs normoxia, #: p<0.05 vs hypoxia.
Fig 6.
miR-34b and miR-337 expression influences cell survival.
Cell viability after 7h of hypoxia in neonatal rat cardiomyocytes treated with negative control, miR-34b and miR-337 mimics (A) or antimiRs (B). Results are expressed in percentage of normoxia. Data are mean ± SEM, n = 5, *: p<0.05 vs normoxia, #: p<0.05 vs hypoxia.
Fig 7.
Proposed mechanism of HDL cardioprotection against IR injury occurring via a STAT3-dependent decrease of miR-34b and miR-337 expression.