Enhanced expression of ß3-adrenoceptors in cardiac myocytes attenuates neurohormone-induced hypertrophic remodeling through nitric oxide synthase.

BACKGROUND: ß1-2-adrenergic receptors (AR) are key regulators of cardiac contractility and remodeling in response to catecholamines. ß3-AR expression is enhanced in diseased human myocardium, but its impact on remodeling is unknown. METHODS AND RESULTS: Mice with cardiac myocyte-specific expression of human ß3-AR (ß3-TG) and wild-type (WT) littermates were used to compare myocardial remodeling in response to isoproterenol (Iso) or Angiotensin II (Ang II). ß3-TG and WT had similar morphometric and hemodynamic parameters at baseline. ß3-AR colocalized with caveolin-3, endothelial nitric oxide synthase (NOS) and neuronal NOS in adult transgenic myocytes, which constitutively produced more cyclic GMP, detected with a new transgenic FRET sensor. Iso and Ang II produced hypertrophy and fibrosis in WT mice, but not in ß3-TG mice, which also had less re-expression of fetal genes and transforming growth factor ß1. Protection from Iso-induced hypertrophy was reversed by nonspecific NOS inhibition at low dose Iso, and by preferential neuronal NOS inhibition at high-dose Iso. Adenoviral overexpression of ß3-AR in isolated cardiac myocytes also increased NO production and attenuated hypertrophy to Iso and phenylephrine. Hypertrophy was restored on NOS or protein kinase G inhibition. Mechanistically, ß3-AR overexpression inhibited phenylephrine-induced nuclear factor of activated T-cell activation. CONCLUSIONS: Cardiac-specific overexpression of ß3-AR does not affect cardiac morphology at baseline but inhibits the hypertrophic response to neurohormonal stimulation in vivo and in vitro, through a NOS-mediated mechanism. Activation of the cardiac ß3-AR pathway may provide future therapeutic avenues for the modulation of hypertrophic remodeling.

Transmission network of an HIV type 1 strain with K103N in young Belgian patients from different risk groups.

Transmitted drug resistance (TDR) influencing nonnucleoside reverse transcriptase inhibitor (NNRTI) activity is increasing among new HIV-1 patients in several countries. As we recently observed an increase of K103N prevalence among new diagnoses in Belgium, we mined the Belgian national sequence database for homologous sequences. The earliest reverse transcriptase (RT) sequences available for drug-naive patients as well as sequences related to treatment failure were included. Fifty-five sequences were aligned and subjected to phylogenetic analysis, revealing the presence of a cluster of 29 virus sequences. All except one of those sequences were from antiretroviral (ARV)-naive patients at the time of sampling, and 22 had the K103N mutation. Epidemiological data of clustered patients were collected through the Institute of Public Health. Seventy-two percent of the clustered patients were infected through homosexual or bisexual contacts while the others reported heterosexual contacts only. All patients reside and were infected in Belgium. Sixteen were diagnosed between January 2011 and June 2012; 14 were aged between 18 and 29 years at the time of diagnosis. Nearly 60% of the clustered patients live close to the city of Namur, where HIV incidence substantially increased in the past 2 years. The identification of this transmission network advocates for local prevention reinforcement and underscores the need for continuous TDR monitoring. The spread of NNRTI TDR could affect ARV initiation schemes and prophylaxis strategies.

Upregulation of IL-17, but not of IL-9, in circulating cells of CIS and relapsing MS patients. Impact of corticosteroid therapy on the cytokine network.

The concomitant production of IL-17A and IL-9, both Th17 cytokines, has not been compared in MS patients. We show that IL-17A but not IL-9 expression by CD3(+) cells was increased during a MS relapse. Co-expression of IL-17A and IL-9 was marginal. In addition to Th1 and Th2 cytokines, IL-17A, IL-6 and IL-23p19 were down-regulated by ivMP, but Foxp3 was not, while an increase in IL-10, TGF-ß1 and IL-27p28 mRNA was observed. This change in the Th17, Treg and IL-10 balance could be an additional mechanism by which corticosteroids shorten the duration of a MS relapse and promote recovery.

Comparative evaluation of the VERSANT HIV-1 RNA 1.0 kinetic PCR molecular system (kPCR) for the quantification of HIV-1 plasma viral load.

BACKGROUND: New automated and ultrasensitive assays are becoming available to monitor HIV-1 plasma viral load, which is an essential marker for the clinical follow-up. OBJECTIVES: To evaluate the performances of the VERSANT HIV-1 RNA 1.0 (kPCR) automated assay in a clinical laboratory setting. STUDY DESIGN: Frozen plasma samples from various HIV-1 subtypes, previously analysed with the VERSANT HIV-1 RNA 3.0 (bDNA) in clinical routine, were retested with the new VERSANT kPCR assay. A comparison was also done with two other commercial assays (NucliSens EasyQ HIV-1 and Abbott real time HIV-1). RESULTS: We observed a good correlation between the viral load measurements obtained with the kPCR assay and the other techniques. Nevertheless, in terms of absolute quantification, we observed discrepancies of more than 0.5 log cop/ml plasma with 36%, 35% and 0% of the samples respectively with NucliSens EasyQ, VERSANT bDNA 3.0 and Abbott real time. No HIV-1 negative sample was amplified by the kPCR. Tenfold dilutions of samples from HIV-1 subtypes A-D, F-H, K, CRF01, CRF02 and CRF06 were analysed to evaluate the kPCR efficiency: the amplification had an efficiency close to the maximum of 2 for each of the subtypes tested. CONCLUSIONS: The VERSANT HIV-1 RNA 1.0 assay (kPCR) is suitable for use in a clinical setting with various HIV-1 subtypes. The plasma viral load quantifications obtained with the kPCR assay were close to those obtained with the Abbott real time HIV-1 assay.

Endothelial beta3-adrenoreceptors mediate nitric oxide-dependent vasorelaxation of coronary microvessels in response to the third-generation beta-blocker nebivolol.

BACKGROUND: The therapeutic effects of nonspecific beta-blockers are limited by vasoconstriction, thus justifying the interest in molecules with ancillary vasodilating properties. Nebivolol is a selective beta1-adrenoreceptor antagonist that releases nitric oxide (NO) through incompletely characterized mechanisms. We identified endothelial beta3-adrenoreceptors in human coronary microarteries that mediate endothelium- and NO-dependent relaxation and hypothesized that nebivolol activates these beta3-adrenoreceptors. METHODS AND RESULTS: Nebivolol dose-dependently relaxed rodent coronary resistance microarteries studied by videomicroscopy (10 micromol/L, -86+/-6% of prostaglandin F2alpha contraction); this was sensitive to NO synthase (NOS) inhibition, unaffected by the beta(1-2)-blocker nadolol, and prevented by the beta(1-2-3)-blocker bupranolol (P<0.05; n=3 to 8). Importantly, nebivolol failed to relax microarteries from beta3-adrenoreceptor-deficient mice. Nebivolol (10 micromol/L) also relaxed human coronary microvessels (-71+/-5% of KCl contraction); this was dependent on a functional endothelium and NO synthase but insensitive to beta(1-2)-blockade (all P<0.05). In a mouse aortic ring assay of neoangiogenesis, nebivolol induced neocapillary tube formation in rings from wild-type but not beta3-adrenoreceptor- or endothelial NOS-deficient mice. In cultured endothelial cells, 10 micromol/L nebivolol increased NO release by 200% as measured by electron paramagnetic spin trapping, which was also reversed by NOS inhibition. In parallel, endothelial NOS was dephosphorylated on threonine(495), and fura-2 calcium fluorescence increased by 91.8+/-23.7%; this effect was unaffected by beta(1-2)-blockade but abrogated by beta(1-2-3)-blockade (all P<0.05). CONCLUSIONS: Nebivolol dilates human and rodent coronary resistance microarteries through an agonist effect on endothelial beta3-adrenoreceptors to release NO and promote neoangiogenesis. These properties may prove particularly beneficial for the treatment of ischemic and cardiac failure diseases through preservation of coronary reserve.

Mutations that affect the tropism of DA and GDVII strains of Theiler's virus in vitro influence sialic acid binding and pathogenicity.

Theiler's murine encephalomyelitis virus (TMEV) is a natural pathogen of the mouse. The different strains of TMEV are divided into two subgroups according to the pathology they provoke. The neurovirulent strains GDVII and FA induce an acute fatal encephalitis, while persistent strains, like DA and BeAn, cause a chronic demyelinating disease associated with viral persistence in the central nervous system. Different receptor usage was proposed to account for most of the phenotype difference between neurovirulent and persistent strains. Persistent but not neurovirulent strains were shown to bind sialic acid. We characterized DA and GDVII derivatives adapted to grow on CHO-K1 cells. Expression of glycosaminoglycans did not influence infection of CHO-K1 cells by parental and adapted viruses. Mutations resulting from adaptation of DA and GDVII to CHO-K1 cells notably mapped to the well-characterized VP1 CD and VP2 EF loops of the capsid. Adaptation of the DA virus to CHO-K1 cells correlated with decreased sialic acid usage for entry. In contrast, adaptation of the GDVII virus to CHO-K1 cells correlated with the appearance of a weak sialic acid usage for entry. The sialic acid binding capacity of the GDVII variant resulted from a single amino acid mutation (VP1-51, Asn-->Ser) located out of the sialic acid binding region defined for virus DA. Mutations affecting tropism in vitro and sialic acid binding dramatically affected the persistence and neurovirulence of the viruses.