Cardiac tissue-resident vesicles differentially modulate anti-fibrotic phenotype by age and sex through synergistic miRNA effects

Aging is a risk factor for cardiovascular disease, the leading cause of death worldwide. Cardiac fibrosis is a harmful result of repeated myocardial infarction that increases risk of morbidity and future injury. Interestingly, both rates and outcomes of cardiac fibrosis differ between young and aged individuals, as well as men and women. Here, for the first time, we identify and isolate matrix-bound extracellular vesicles from the left ventricles (LVs) of young or aged males and females in both human and murine models. These LV vesicles (LVVs) show differences in morphology and content between these four cohorts in both humans and mice. LVV effects on fibrosis were also investigated in vitro, and aged male LVVs were pro-fibrotic while other LVVs were anti-fibrotic. From these LVVs, we could identify therapeutic miRNAs to promote anti-fibrotic effects. Four miRNAs were identified and together, but not individually, demonstrated significant cardioprotective effects when transfected. This suggests that miRNA synergy can regulate cell response, not just individual miRNAs, and also indicates that biological agent-associated therapeutic effects may be recapitulated using non-immunologically active agents. Furthermore, that chronic changes in LVV miRNA content may be a major factor in sex- and age-dependent differences in clinical outcomes of cardiac fibrosis.

Mesenchymal stromal cells for improvement of cardiac function following acute myocardial infarction: a matter of timing

Acute myocardial infarction (AMI) is the leading cause of cardiovascular death and remains the most common cause of heart failure. Reopening of the occluded artery, i.e., reperfusion, is the only way to save the myocardium. However, the expected benefits of reducing infarct size are disappointing due to the reperfusion paradox, which also induces specific cell death. These ischemia-reperfusion (I/R) lesions can account for up to 50% of final infarct size, a major determinant for both mortality and the risk of heart failure (morbidity). In this review, we provide a detailed description of the cell death and inflammation mechanisms as features of I/R injury and cardioprotective strategies such as ischemic postconditioning as well as their underlying mechanisms. Due to their biological properties, the use of mesenchymal stromal/stem cells (MSCs) has been considered a potential therapeutic approach in AMI. Despite promising results and evidence of safety in preclinical studies using MSCs, the effects reported in clinical trials are not conclusive and even inconsistent. These discrepancies were attributed to many parameters such as donor age, in vitro culture, and storage time as well as injection time window after AMI, which alter MSC therapeutic properties. In the context of AMI, future directions will be to generate MSCs with enhanced properties to limit cell death in myocardial tissue and thereby reduce infarct size and improve the healing phase to increase postinfarct myocardial performance.

THE ROLE OF BIOMARKER MACROPHAGE MIGRATION INHIBITORY FACTOR IN CARDIAC REMODELING PREDICTION IN PATIENTS WITH ST-SEGMENT ELEVATION MYOCARDIAL INFARCTION

OBJECTIVE

The aim: To estimate the role of macrophage migration inhibitory factor and soluble ST2 in predicting the left ventricle remodeling six months after ST-segment elevation myocardial infarction.

PATIENTS AND METHODS

Materials and methods: The study involved 134 ST-segment elevation myocardial infarction patients. Occurrence of post-percutaneous coronary (PCI) intervention epicardial blood flow of TIMI <3 or myocardial blush grade 0-1 along with ST resolution <70% within 2 hours after PCI was qualified as the no-reflow condition. Left ventricle remodeling was defined after 6-months as an increase in left ventricle end-diastolic volume and/or end-systolic volume by more than 10%.

RESULTS

Results: A logistic regression formula was evaluated. Included biomarkers were macrophage migration inhibitory factor and sST2, left ventricle ejection fraction: Y=exp(-39.06+0.82EF+0.096ST2+0.0028MIF) / (1+exp(-39.06+0.82EF+0.096ST2+0.0028MIF)). The estimated range is from 0 to 1 point. Less than 0.5 determines an adverse outcome, and more than 0.5 is a good prognosis. This equation, with sensitivity of 77 % and specificity of 85%, could predict the development of adverse left ventricle remodeling six months after a coronary event (AUC=0.864, CI 0.673 to 0.966, p<0.05).

CONCLUSION

Conclusions: A combination of biomarkers gives a significant predicting result in the formation of adverse left ventricular remodeling after ST-segment elevation myocardial infarction.

Knockout of macrophage migration inhibitory factor accentuates side-stream smoke exposure-induced myocardial contractile dysfunction through dysregulated mitophagy

Second hand smoke exposure increases the prevalence of chronic diseases partly attributed to inflammatory responses. Macrophage migration inhibitory factor (MIF), a proinflammatory cytokine, is involved in the pathogenesis of multiple diseases although its role in second hand smoke exposure-induced cardiac anomalies remains elusive. This study evaluated the impact of MIF knockout on side-stream smoke exposure-induced cardiac pathology and underlying mechanisms. Adult WT and MIF knockout (MIFKO) mice were placed in a chamber exposed to cigarette smoke for 1 h daily for 60 consecutive days. Echocardiographic, cardiomyocyte function and intracellular Ca²⁺ handling were evaluated. Autophagy, mitophagy and apoptosis were examined using western blot. DHE staining was used to evaluate superoxide anion (O₂^-) generation. Masson trichrome staining was employed to assess interstitial fibrosis. Our data revealed that MIF knockout accentuated side-stream smoke-induced cardiac anomalies in fractional shortening, cardiomyocyte function, intracellular Ca²⁺ homeostasis, myocardial ultrastructure and mitochondrial content along with overt apoptosis and O₂^- generation. In addition, unfavorable effects of side-stream smoke were accompanied by excessive formation of autophagolysosome and elevated TFEB, the effect of which was exacerbated by MIF knockout. Recombinant MIF rescued smoke extract-induced myopathic anomalies through promoting AMPK activation, mitophagy and lysosomal function. Taken together, our data suggest that MIF serves as a protective factor against side-stream smoke exposure-induced myopathic changes through facilitating mitophagy and autophagolysosome formation.

Prognostic Value of Pre-Infarction Angina Combined with Mean Platelet Volume to Lymphocyte Count Ratio for No-Reflow and Short-Term Mortality in Patients with ST-Segment Elevation Myocardial Infarction Undergoing Percutaneous Coronary Intervention

Background

The aim of the present study was to investigate the clinical predictive value of pre-infarction angina (PIA) combined with mean platelet volume to lymphocyte count ratio (MPVLR) for no-reflow phenomenon and short-term mortality in patients with ST-segment elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI).

Material/Methods

A total of 1009 STEMI patients who had undergone PCI were enrolled and subdivided into 4 groups based on the occurrence of PIA and the presence of MPVLR above or below the cutoff value. Analysis of the predictors of the no-reflow phenomenon and 90-day mortality was conducted. Further, evaluation and comparison of the clinical predictive value of PIA, MPVLR, and their combination were done.

Results

Both MPVLR (odds ratio [OR]=1.476, 95% confidence interval [CI]: 1.401 to 1.756, P<0.001; hazard ratio [HR]=1.430, 95% CI: 1.287 to 1.643, P<0.001) and PIA (OR=0.905, 95% CI: 0.783 to 0.986, P<0.001; HR=0.878, 95% CI: 0.796 to 0.948, P<0.001) were independent predictors of no-reflow phenomenon and 90-day mortality. Spearman’s rank correlation test revealed that MPVLR (r=−0.297, P<0.001), monocyte to lymphocyte count ratio (MLR) (r=−0.211, P<0.001) and neutrophil to lymphocyte count ratio (NLR) (r=−0.389, P<0.001) in peripheral blood were significantly negatively correlated with postoperative left ventricular ejection fraction (LVEF). Upon comparing the area under curve (AUC), the MPVLR combined with PIA achieved better performance in differentiating no-reflow phenomenon (AUC=0.847, 95% CI: 0.821 to 0.874) and 90-day mortality (AUC=0.790, 95% CI: 0.725 to 0.855), than the GRACE score, MPVLR and PIA alone, and had similar performance to all other pairwise combinations of the GRACE score, MPVLR and PIA.

Conclusions

High MPVLR and PIA were independent predictors of the no-reflow phenomenon and 90-day mortality in patients with STEMI after PCI. Moreover, Combined application of MPVLR and PIA can effectively predict the occurrence of the no-reflow phenomenon and 90-day mortality.