PAFR-deficiency alleviates myocardial ischemia/reperfusion injury in mice via suppressing inflammation, oxidative stress and apoptosis.

Myocardial ischemia/reperfusion (I/R) still have high morbidity and mortality worldwide. Platelet activating factor (PAF) is a potent phospholipid regulator of inflammation. PAF acts on a single receptor (PAFR), which is expressed on cellular and nuclear membranes of various cell types. The study is aimed to explore if PAFR could modulate myocardial I/R injury in mice. PAFR expressions began to up-regulate at 1 h, and reached peak at 24 h. PAFR deletion markedly attenuated myocardial I/R injury, evidenced by the reduced infarct size and the improved cardiac function. Furthermore, PAFR-knockout inhibited inflammatory response, as demonstrated by down-regulated pro-inflammatory cytokines and chemokine, as well as the inactivation of nuclear factor κB (NF-κB). Additionally, PAFR-absence ameliorated oxidative stress induced by myocardial I/R, associated with the up-regulation of superoxide dismutase (SOD) and nuclear respiratory factor 2 (Nrf-2) activity. Finally, PAFR-deficiency impeded apoptosis, which was proved by the decreasing in terminal deoxynucleotidyl transferase (TdT)-mediated dNTP nick end labeling (TUNEL)-positive myocytes, and Caspase-3 cleavage. And the activation of Janus kinase 1-signal transducer and activator of transcription 1 (JAK1/STAT1) pathway was also suppressed by PAFR-knockout. The findings above were confirmed in lipopolysaccharide (LPS)-incubated cardiomyocytes with or without PAFR expressions in vitro. In summary, we supposed that inhibiting PAFR reduced inflammation, oxidative stress and apoptosis, and thus might be a promising therapeutic strategy to alleviate myocardial I/R injury.

miR-487b mitigates chronic heart failure through inhibition of the IL-33/ST2 signaling pathway.

We investigated the effects of microRNA-587b (miR-487b) in a rat model of chronic heart failure (CHF). Wistar rats were assigned to 10 groups (n=8 per group). Expression of interleukin-33 (IL-33), somatostatin 2 (ST2), IL-6, and TNF-α was higher in the CHF group than the control group. In the CHF, negative control (NC) for si-IL-33, NC for miR-487b mimic, NC for miR-487b inhibitor, and miR-487b inhibitor + si IL-33 groups, as compared to the blank and sham groups: steroid binding protein (SBP), D binding protein (DBP), left ventricular systolic pressure (LVSP), ± dp/dtmax, and superoxide dismutase (SOD) were all lower; myocardial fibrosis, MDA, left ventricular end-diastolic pressure (LVEDP), myocardial apoptosis rate, IL-6, and TNF-α were all higher; levels of IL-33 and ST2 mRNA and protein were higher; and levels of miR-487b were lower. Levels of IL-33 and ST2 mRNA and protein were lower, and SBP, DBP, LVSP, ± dp/dtmax, and SOD were higher in the miR-487b mimic and si-IL-33 groups than the CHF group. Expression of miR-487b was increased in the miR-487b mimic group, and expression of IL-33 and ST2 were increased and expression of miR-487b was decreased in the miR-487b inhibitor group. MiR-487b reduces apoptosis, inflammatory responses, and fibrosis in CHF by suppressing IL-33 through inhibition the IL-33/ST2 signaling pathway.