Regulation of Expression of B7 by Murine Langerhans Cells: A Direct Relationship Between B7 mRNA Levels and the Level of Surface Expression of B7 by Langerhans Cells

Cultured BALB/c epidermal Langerhans cells express high levels of the costimulatory molecule B7 on their surfaces relative to levels expressed on fresh Langerhans cells. Quantitation of relative amounts of B7 mRNA in fresh epidermal cells and cultured epidermal cells following amplification of mRNA signals via reverse transcriptase – polymerase chain reaction, hybridization of PCR products with radiolabeled internal oligonucleotide probes, resolution of hybrids in non-denaturing polyacrylamide gels, and detection by autoradiography revealed dramatically (approximately one thousandfold) higher levels of B7 mRNA in cultured epidermal cells (10-40% 1-A+) as compared with fresh epidermal cells (1 – 4% I-A+). Levels of B7 mRNA in cultured epidermal cells were also substantially greater than those detected in a reference B lymphoma cell line (CH-1). Analysis of 87 mRNA expression in subpopulations of cultured epidermal cells demonstrated that essentially all of the B7 mRNA was present in Langerhans cells; cells bearing I-A and CD45 antigens. Cultured keratinocytes did not contain appreciable amounts of B7 mRNA. These results are consistent with previous data regarding surface expression of 87 by cLC and also demonstrate that fLC are essentially devoid of B7 mRNA and surface protein

Cardiac myosin activation with omecamtiv mecarbil in systolic heart failure

BACKGROUND The selective cardiac myosin activator omecamtiv mecarbil has been shown to improve cardiac function in patients with heart failure with a reduced ejection fraction. Its effect on cardiovascular outcomes is unknown. METHODS We randomly assigned 8256 patients (inpatients and outpatients) with symptomatic chronic heart failure and an ejection fraction of 35% or less to receive omecamtiv mecarbil (using pharmacokinetic-guided doses of 25 mg, 37.5 mg, or 50 mg twice daily) or placebo, in addition to standard heart-failure therapy. The primary outcome was a composite of a first heart-failure event (hospitalization or urgent visit for heart failure) or death from cardiovascular causes. RESULTS During a median of 21.8 months, a primary-outcome event occurred in 1523 of 4120 patients (37.0%) in the omecamtiv mecarbil group and in 1607 of 4112 patients (39.1%) in the placebo group (hazard ratio, 0.92; 95% confidence interval [CI], 0.86 to 0.99; P = 0.03). A total of 808 patients (19.6%) and 798 patients (19.4%), respectively, died from cardiovascular causes (hazard ratio, 1.01; 95% CI, 0.92 to 1.11). There was no significant difference between groups in the change from baseline on the Kansas City Cardiomyopathy Questionnaire total symptom score. At week 24, the change from baseline for the median N-terminal pro-B-type natriuretic peptide level was 10% lower in the omecamtiv mecarbil group than in the placebo group; the median cardiac troponin I level was 4 ng per liter higher. The frequency of cardiac ischemic and ventricular arrhythmia events was similar in the two groups. CONCLUSIONS Among patients with heart failure and a reduced ejection, those who received omecamtiv mecarbil had a lower incidence of a composite of a heart-failure event or death from cardiovascular causes than those who received placebo. (Funded by Amgen and others; GALACTIC-HF ClinicalTrials.gov number, NCT02929329; EudraCT number, 2016 -002299-28.)