MicroRNA Profiling Identifies MicroRNA-155 as an Adverse Mediator of Cardiac Injury and Dysfunction During Acute Viral Myocarditis

Rationale: Viral myocarditis results from an adverse immune response to cardiotropic viruses, which causes irreversible myocyte destruction and heart failure in previously healthy people. The involvement of microRNAs and their usefulness as therapeutic targets in this process are unknown. Objective: To identify microRNAs involved in viral myocarditis pathogenesis and susceptibility. Methods and Results: Cardiac microRNAs were profiled in both human myocarditis and in Coxsackievirus B3-injected mice, comparing myocarditis-susceptible with nonsusceptible mouse strains longitudinally. MicroRNA responses diverged depending on the susceptibility to myocarditis after viral infection in mice. MicroRNA-155, -146b, and -21 were consistently and strongly upregulated during acute myocarditis in both humans and susceptible mice. We found that microRNA-155 expression during myocarditis was localized primarily in infiltrating macrophages and T lymphocytes. Inhibition of microRNA-155 by a systemically delivered LNA-anti-miR attenuated cardiac infiltration by monocyte-macrophages, decreased T lymphocyte activation, and reduced myocardial damage during acute myocarditis in mice. These changes were accompanied by the derepression of the direct microRNA-155 target PU.1 in cardiac inflammatory cells. Beyond the acute phase, microRNA-155 inhibition reduced mortality and improved cardiac function during 7 weeks of follow-up. Conclusions: Our data show that cardiac microRNA dysregulation is a characteristic of both human and mouse viral myocarditis. The inflammatory microRNA-155 is upregulated during acute myocarditis, contributes to the adverse inflammatory response to viral infection of the heart, and is a potential therapeutic target for viral myocarditis.     

The amino terminus of the salmonid alphavirus capsid protein determines subcellular localization and inhibits cellular proliferation

Salmonid alphavirus (SAV) is the most divergent member of the family Togaviridae and constitutes a threat to farming of salmonid fish in Europe. Here, we report cloning, expression and preliminary functional analysis of the capsid protein of SAV, confirming it to be expressed as an approximately 31-kDa protein in infected cells. The protein localizes strictly to the cytoplasm in Chinook salmon embryo cells, and either to the nucleus or cytoplasm in bluegill fry cells. An expression study of full-length and different truncated versions of the SAV capsid fused to the enhanced green fluorescent protein demonstrated that the localization is independent of other viral components in both cell lines, and controlled by the N-terminal 82 aa, which include a conserved, predicted helix and a downstream positively charged region. Thus, the results suggest that the SAV capsid possesses a cell-type-dependent potential for nuclear import and export. Moreover, the SAV capsid and its N-terminal 82 aa were shown to be associated with inhibition of cellular proliferation, a hallmark of the cytopathic effect caused by SAV. These results highlight that the SAV capsid is a multifunctional protein with possible importance for pathogenesis.     

A phase I trial of pre-operative radiotherapy for prostate cancer: Clinical and translational studies

BACKGROUND AND PURPOSE: Selected patients undergoing radical prostatectomy for localized prostate cancer can be at high-risk for pT3 disease and require subsequent radiotherapy. In a phase I trial, we investigated the feasibility of pre-operative radiotherapy for this patient subset. MATERIALS AND METHODS: Eligibility criteria were: T1/T2N0M0 tumors plus (i) Gleason >or=7, PSA>10 ng/ml and <35 ng/ml, or (ii), PSA >15 ng/ml and less <35 ng/ml (any Gleason). Patients received 25 Gy in five fractions of radiotherapy followed by radical prostatectomy. Trial endpoints included intra-operative morbidity and late toxicity following combined treatment. We also stained pre- and post-radiotherapy prostate samples for DNA damage response proteins. RESULTS: Between 2001 and 2004, 15 patients were entered on trial. Thirteen patients completed combined-modality treatment. Only one patient had signs of intra-operative inflammation. No patient had post-operative complication. There was no severe late gastrointestinal toxicity. Late genitourinary toxicity consisted of severe urinary incontinence in 2 of 13 patients. From a translational standpoint, irradiated prostate tumor tissues had long-term activation of the CDK-inhibitor p21(WAF) associated with reduced cell proliferation. CONCLUSION: Intra-operative morbidity is low following short-course, pre-operative radiotherapy. A phase II trial is planned to fully document biochemical response with this combined-modality approach.     

In Vivo Reversal of Multidrug Resistance by Two New Dihydropyridine Derivatives, S16317 and S16324

Two new dihydropyridine derivatives with low calcium channel affinity, S16317 and S16324, were found to fully overcome multidrug resistance in vitro. These two compounds increased doxorubicin cytotoxicity on the human COLO 320DM cell line and completely reversed the vincristine resistance of murine P388/VCR cells. In vivo, S16324 administered p.o. (200 mg/kg on days 1 to 4) or i.p. (50mg/kg on days 1, 5, 9) in combination with vincristine (i.p.) restored the antitumor activity of vincristine in P388/VCR-bearing mice. S16317 showed a reversing activity when administered p.o., i.v. (days 1 to 4) or i.p. (days 1, 5, 9) at the same dose (25 mg/kg), suggesting a remarkable bioavailability. Moreover, these two compounds potentiated the antitumor activity of vincristine in the sensitive P388 leukemia, increasing the number of long-term survivors. These results suggest that combination chemotherapy using S16317 or S16324 would be effective not only in circumventing multidrug resistance but also in preventing the emergency of a population of resistant tumor cells in sensitive tumors.     

Right heart obstruction from a balloon-like sinus of Valsalva aneurysm in a patient with Down syndrome

A 40-year-old man with Down syndrome presented with right heart failure. He was markedly obese and had severe developmental delay. There was marked edema and an early diastolic sound. Transthoracic echocardiography suggested a right heart mass. Transesophageal echocardiography revealed an unruptured balloon-like sinus of Valsalva aneurysm within the right atrium that obstructed the tricuspid orifice. The patient died in hospital of mixed obstructive and/or septic shock.     

A noncognate aminoacyl-tRNA synthetase that may resolve a missing link in protein evolution

Efforts to delineate the advent of many enzymes essential to protein translation are often limited by the fact that the modern genetic code evolved before divergence of the tree of life. Glutaminyl-tRNA synthetase (GlnRS) is one noteworthy exception to the universality of the translation apparatus. In eukaryotes and some bacteria, this enzyme is essential for the biosynthesis of Gln-tRNAGln, an obligate intermediate in translation. GlnRS is absent, however, in archaea, and most bacteria, organelles, and chloroplasts. Phylogenetic analyses predict that GlnRS arose from glutamyl-tRNA synthetase (GluRS), via gene duplication with subsequent evolution of specificity. A pertinent question to ask is whether, in the advent of GlnRS, a transient GluRS-like intermediate could have been retained in an extant organism. Here, we report the discovery of an essential GluRS-like enzyme (GluRS2), which coexists with another GluRS (GluRS1) in Helicobacter pylori. We show that GluRS2's primary role is to generate Glu-tRNAGln, not Glu-tRNAGlu. Thus, GluRS2 appears to be a transient GluRS-like ancestor of GlnRS and can be defined as a GluGlnRS.