Ubiquitin-proteasome-system and enzymes of energy metabolism in skeletal muscle of patients with HFpEF and HFrEF.

BACKGROUND: Skeletal muscle (SM) alterations contribute to exercise intolerance in heart failure patients with preserved (HFpEF) or reduced (HFrEF) left ventricular ejection fraction (LVEF). Protein degradation via the ubiquitin-proteasome-system (UPS), nuclear apoptosis, and reduced mitochondrial energy supply is associated with SM weakness in HFrEF. These mechanisms are incompletely studied in HFpEF, and a direct comparison between these groups is missing. METHODS AND RESULTS: Patients with HFpEF (LVEF ≥ 50%, septal E/e' > 15 or >8 and NT-proBNP > 220 pg/mL, n = 20), HFrEF (LVEF ≤ 35%, n = 20) and sedentary control subjects (Con, n = 12) were studied. Inflammatory markers were measured in serum, and markers of the UPS, nuclear apoptosis, and energy metabolism were determined in percutaneous SM biopsies. Both HFpEF and HFrEF showed increased proteolysis (MuRF-1 protein expression, ubiquitination, and proteasome activity) with proteasome activity significantly related to interleukin-6. Proteolysis was more pronounced in patients with lower exercise capacity as indicated by peak oxygen uptake in per cent predicted below the median. Markers of apoptosis did not differ between groups. Mitochondrial energy supply was reduced in HFpEF and HFrEF (complex-I activity: -31% and -53%; malate dehydrogenase activity: -20% and -29%; both P < 0.05 vs. Con). In contrast, short-term energy supply via creatine kinase was increased in HFpEF but decreased in HFrEF (47% and -45%; P < 0.05 vs. Con). CONCLUSIONS: Similarly to HFrEF, skeletal muscle in HFpEF is characterized by increased proteolysis linked to systemic inflammation and reduced exercise capacity. Energy metabolism is disturbed in both groups; however, its regulation seems to be severity-dependent.

Selenoprotein P in Myocardial Infarction With Cardiogenic Shock.

BACKGROUND: Reperfusion strategies in acute myocardial infarction (AMI) may result in ischemia reperfusion injury characterized by increased oxidative stress, inflammation, and ultimately death of myocardial tissue which may be of particular importance in infarct-related cardiogenic shock (CS). Many anti-oxidative and immune regulatory processes depend on selenium which in large proportions is bound to circulating selenoprotein P (SelP). Individual SelP patterns may therefore be associated with inflammatory response and possibly mortality in patients with CS post AMI. METHODS: In the randomized Intra-Aortic Balloon Pump in cardiogenic Shock II (IABP-SHOCK II)-trial, 600 patients with CS complicating AMI were assigned to therapy with or without IABP. In a predefined biomarker substudy of 147 patients, we analyzed SelP levels 1 and 3 days following randomization. Samples were compared with healthy controls and associations with the unspecific inflammatory marker C-reactive protein (CRP) were analyzed. RESULTS: Compared with controls SelP levels in patients with infarct-related CS were markedly higher (2.7-fold at day 1 and 5.7-fold at day 3 following AMI, all P < 0.001). Thirty-day mortality was significantly higher in patients with SelP levels above the 75th percentile at day 3 following AMI (26% vs. 46%, P = 0.045). SelP was significantly proportionally correlated with CRP 1 (R = 0.762, P < 0.0001) and 3 days (R = 0.777 P < 0.0001) following AMI. CONCLUSION: SelP levels are significantly increased post AMI with CS. Higher SelP levels are associated with increased CRP levels indicative for inflammatory processes. Future studies should focus on the characterization of SelP profiles following AMI and the identification of pathomechanisms affected by SelP.