Circulating T cell specific extracellular vesicle profiles in cardiac allograft acute cellular rejection.

There is a critical need for biomarkers of acute cellular rejection (ACR) in organ transplantation. We hypothesized that ACR leads to changes in donor-reactive T cell small extracellular vesicle (sEV) profiles in transplant recipient circulation that match the kinetics of alloreactive T cell activation. In rodent heart transplantation, circulating T cell sEV quantities (P < .0001) and their protein and mRNA cargoes showed time-specific expression of alloreactive and regulatory markers heralding early ACR in allogeneic transplant recipients but not in syngeneic transplant recipients. Next generation sequencing of their microRNA cargoes identified novel candidate biomarkers of ACR, which were validated by stem loop quantitative reverse transcription polymerase chain reaction (n = 10). Circulating T cell sEVs enriched from allogeneic transplant recipients mediated targeted cytotoxicity of donor cardiomyocytes by apoptosis assay (P < .0001). Translation of the concept and EV methodologies to clinical heart transplantation demonstrated similar upregulation of circulating T cell sEV profiles at time points of grade 2 ACR (n = 3 patients). Furthermore, T cell receptor sequencing of T cell sEV mRNA cargo demonstrated expression of T cell clones with intact complementarity determining region 3 signals. These data support the diagnostic potential of T cell sEVs as noninvasive biomarker of ACR and suggest their potential functional roles.

Different Clinical Course and Complications in Interagency Registry for Mechanically Assisted Circulatory Support 1 (INTERMACS) Patients Managed With or Without Extracorporeal Membrane Oxygenation.

Extracorporeal membrane oxygenation (ECMO) as a bridge to left ventricular assist device (LVAD) implantation has shown promise in improving end-organ function and optimizing outcomes in some critically ill patients, but the practice remains controversial. Retrospective review of patients who received LVADs from May 2008 to September 2016 at a high-volume, tertiary care cardiovascular center was performed. Subjects were Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) class 1 patients divided into ECMO bridge and non-ECMO bridge cohorts. Patient demographics, adverse events, and survival at immediate and 1 year postoperative time points were compared between groups. In total, 235 patients received a HeartMate II or HVAD during the study period. Among INTERMACS 1 patients, 18 were ECMO bridge and 17 were non-ECMO bridge. Age, gender and bridge-to-transplant proportions (50% vs. 53%) were similar between groups. The ECMO bridge group had lower hemoglobin (7.9 ± 1.1 vs. 10.2 ± 2.2; p < 0.01), platelet (101 [70] vs. 176 [115]; p < 0.05), and prealbumin levels (10.6 ± 4.3 vs. 17.3 ± 7.7; p < 0.01). Nearly half (n = 8; 44%) of the ECMO bridge patients required packed red blood cell transfusions before VAD and were more likely to be on an epinephrine drip (78% vs. 12%; p < 0.01). However, along with these adjunctive measures, the ECMO bridge did effectively improve hemodynamic profiles by the time of VAD implant resulting in lower central venous pressure (7.7 ± 2.5 vs. 10.4 ± 4.8; p < 0.01) and mean pulmonary arterial pressure (18 ± 9 vs. 32 ± 8; p < 0.01). It also allowed for restoration of end-organ function as noted by comparable creatinine (1.0 [1.2] vs. 1.4 [0.6]) and total bilirubin levels (1.6 ± 1 vs.1.5 ± 1.7) between the two groups. There was no difference in rates of adverse events. Survival at 30 days postoperative and at 1 year (77% vs. 88%; p = 0.6) was similar. This study demonstrates that ECMO bridge is a central component of a multifaceted strategy for stabilization of select patients with severe hemodynamic instability before LVAD implantation. Further studies to optimize patient selection should be further explored.

Epigenetic regulation of soluble guanylate cyclase (sGC) ß1 in breast cancer cells.

Soluble guanylate cyclase (sGC) is a heterodimer composed of α and ß subunits. The loss of sGCß1 has been implicated in several vascular and nonvascular diseases. Our analysis showed that higher levels of sGCß1 in breast cancer tissues are correlated with greater survival probability than lower sGCß1 levels. However, there is no information on sGC regulation by epigenetic mechanisms. We examined the role of histone deacetylase (HDAC) inhibitors in regulating sGCα1 and -ß1 expression in human breast cancer MDA-MB-231 and MDA-MB-468 cell lines. The class I HDAC inhibitors increased the expression of sGCß1 more than sGCα1. Transient overexpression of HDAC3, but not HDAC1 or HDAC2, significantly reduced sGCß1 mRNA. Chromatin immunoprecipitation assay confirmed an enhanced binding of HDAC3 to the sGCß1 proximal promoter, which could be reversed by panobinostat (LBH-589) treatment. Mutations at the CCAAT binding sequence, a major element regulating sGCß1 expression, markedly reduced the efficacy of LBH-589 in augmenting sGCß1 promoter activity. LBH-589 markedly enhanced the binding of nuclear transcription factor Y, subunit α, to the sGCß1 promoter (CCAAT binding sequence). In summary, HDAC3 is an endogenous antagonist of sGCß1 expression. Inhibition of HDAC3 with targeted therapy could benefit treatment of the diseases associated with sGCß1 down-regulation and/or deficiency such as cancer and several vascular-related diseases.-Sotolongo, A., Mónica, F. Z., Kots, A., Xiao, H., Liu, J., Seto, E., Bian, K., Murad, F. Epigenetic regulation of soluble guanylate cyclase (sGC) ß1 in breast cancer cells.

NOS-2 signaling and cancer therapy.

The role of NO and cGMP signaling in tumor biology has been extensively studied during the past three decades. However, whether the pathway is beneficial or detrimental in cancer is still open to question. We suggest several reasons for this ambiguity: first, although NO participates in normal signaling (e.g., vasodilation and neurotransmission), NO is also a cytotoxic or apoptotic molecule when produced at high concentrations by inducible nitric-oxide synthase (iNOS or NOS-2). In addition, the cGMP-dependent (NO/sGC/cGMP pathway) and cGMP-independent (NO oxidative pathway) components may vary among different tissues and cell types. Furthermore, solid tumors contain two compartments: the parenchyma (neoplastic cells) and the stroma (nonmalignant supporting tissues including connective tissue, blood vessels, and inflammatory cells) with different NO biology. Thus, the NO/sGC/cGMP signaling molecules in tumors as well as the surrounding tissue must be further characterized before targeting this signaling pathway for tumor therapy. In this review, we focus on the NOS-2 expression in tumor and surrounding cells and summarized research outcome in terms of cancer therapy. We propose that a normal function of the sGC-cGMP signaling axis may be important for the prevention and/or treatment of malignant tumors. Inhibiting NOS-2 overexpression and the tumor inflammatory microenvironment, combined with normalization of the sGC/cGMP signaling may be a favorable alternative to chemotherapy and radiotherapy for malignant tumors.