Karima Jnaoui

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 β-blockers are limited by vasoconstriction, thus justifying the interest in molecules with ancillary vasodilating properties. Nebivolol is a selective β1-adrenoreceptor antagonist that releases nitric oxide (NO) through incompletely characterized mechanisms. We identified endothelial β3-adrenoreceptors in human coronary microarteries that mediate endothelium- and NO-dependent relaxation and hypothesized that nebivolol activates these β3-adrenoreceptors. Methods and Results—Nebivolol dose-dependently relaxed rodent coronary resistance microarteries studied by videomicroscopy (10 &mgr;mol/L, −86±6% of prostaglandin F2α contraction); this was sensitive to NO synthase (NOS) inhibition, unaffected by the β1-2-blocker nadolol, and prevented by the β1-2-3-blocker bupranolol (P<0.05; n=3 to 8). Importantly, nebivolol failed to relax microarteries from β3-adrenoreceptor–deficient mice. Nebivolol (10 &mgr;mol/L) also relaxed human coronary microvessels (−71±5% of KCl contraction); this was dependent on a functional endothelium and NO synthase but insensitive to β1-2-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 β3-adrenoreceptor– or endothelial NOS–deficient mice. In cultured endothelial cells, 10 &mgr;mol/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 threonine495, and fura-2 calcium fluorescence increased by 91.8±23.7%; this effect was unaffected by β1-2-blockade but abrogated by β1-2-3-blockade (all P<0.05). Conclusions—Nebivolol dilates human and rodent coronary resistance microarteries through an agonist effect on endothelial β3-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.

Enhanced Expression of β3-Adrenoceptors in Cardiac Myocytes Attenuates Neurohormone-Induced Hypertrophic Remodeling Through Nitric Oxide Synthase

Background— &bgr;1-2-adrenergic receptors (AR) are key regulators of cardiac contractility and remodeling in response to catecholamines. &bgr;3-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 &bgr;3-AR (&bgr;3-TG) and wild-type (WT) littermates were used to compare myocardial remodeling in response to isoproterenol (Iso) or Angiotensin II (Ang II). &bgr;3-TG and WT had similar morphometric and hemodynamic parameters at baseline. &bgr;3-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 &bgr;3-TG mice, which also had less re-expression of fetal genes and transforming growth factor &bgr;1. 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 &bgr;3-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, &bgr;3-AR overexpression inhibited phenylephrine-induced nuclear factor of activated T-cell activation. Conclusions— Cardiac-specific overexpression of &bgr;3-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 &bgr;3-AR pathway may provide future therapeutic avenues for the modulation of hypertrophic remodeling.

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.

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-β1 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.

Genotypic evaluation of etravirine sensitivity of clinical human immunodeficiency virus type 1 (HIV-1) isolates carrying resistance mutations to nevirapine and efavirenz.

Abstract Background: Etravirine is a second-generation non-nucleoside reverse transcriptase inhibitor (NNRTI) with a pattern of resistance mutations quite distinct from the current NNRTIs. Methods: We collected all routine samples of HIV-1 patients followed in the AIDS reference laboratory of UCLouvain (in 2006 and 2007) carrying resistance-associated mutations to nevirapine (NVP) or efavirenz (EFV). The sensitivity to Etravirine was estimated using three different drug resistance algorithms: ANRS (July 2008), IAS (December 2008) and Stanford (November 2008). We also verified whether the mutations described as resistance mutations are not due to virus polymorphisms by the study of 58 genotypes of NNRTI-naïve patients. Results: Sixty one samples harboured resistance to NVP and EFV: 41/61 had at least one resistance mutation to Etravirine according to ANRS-IAS algorithms; 42/61 samples had at least one resistance mutation to Etravirine according to the Stanford algorithm. 48 and 53 cases were fully sensitive to Etravirine according to ANRS-IAS and Stanford algorithms, respectively. Three cases harboured more than three mutations and presented a pattern of high-degree resistance to Etravirine according to ANRS-IAS algorithm, while one case harboured more than three mutations and presented high degree resistance to Etravirine according to the Stanford algorithm. The V106I and V179D mutations were more frequent in the ARV-naïve group than in the NNRTI-experienced one. Conclusions: According to the currently available algorithms, Etravirine can still be used in the majority of patients with virus showing resistance to NVP and/or EFV, if a combination of other active drugs is included.

Transmission of primary resistance mutation K103N in a cluster of Belgian young patients from different risk groups.

We analysed the distribution of an HIV‐1 subtype B strain resistant to efavirenz and nevirapine among incident infections in the Belgian population.