Phospholemman Phosphorylation Regulates Vascular Tone, Blood Pressure, and Hypertension in Mice and Humans.

BACKGROUND: Although it has long been recognized that smooth muscle Na/K ATPase modulates vascular tone and blood pressure (BP), the role of its accessory protein phospholemman has not been characterized. The aim of this study was to test the hypothesis that phospholemman phosphorylation regulates vascular tone in vitro and that this mechanism plays an important role in modulation of vascular function and BP in experimental models in vivo and in humans. METHODS: In mouse studies, phospholemman knock-in mice (PLM3SA; phospholemman [FXYD1] in which the 3 phosphorylation sites on serines 63, 68, and 69 are mutated to alanines), in which phospholemman is rendered unphosphorylatable, were used to assess the role of phospholemman phosphorylation in vitro in aortic and mesenteric vessels using wire myography and membrane potential measurements. In vivo BP and regional blood flow were assessed using Doppler flow and telemetry in young (14-16 weeks) and old (57-60 weeks) wild-type and transgenic mice. In human studies, we searched human genomic databases for mutations in phospholemman in the region of the phosphorylation sites and performed analyses within 2 human data cohorts (UK Biobank and GoDARTS [Genetics of Diabetes Audit and Research in Tayside]) to assess the impact of an identified single nucleotide polymorphism on BP. This single nucleotide polymorphism was expressed in human embryonic kidney cells, and its effect on phospholemman phosphorylation was determined using Western blotting. RESULTS: Phospholemman phosphorylation at Ser63 and Ser68 limited vascular constriction in response to phenylephrine. This effect was blocked by ouabain. Prevention of phospholemman phosphorylation in the PLM3SA mouse profoundly enhanced vascular responses to phenylephrine both in vitro and in vivo. In aging wild-type mice, phospholemman was hypophosphorylated, and this correlated with the development of aging-induced essential hypertension. In humans, we identified a nonsynonymous coding variant, single nucleotide polymorphism rs61753924, which causes the substitution R70C in phospholemman. In human embryonic kidney cells, the R70C mutation prevented phospholemman phosphorylation at Ser68. This variant's rare allele is significantly associated with increased BP in middle-aged men. CONCLUSIONS: These studies demonstrate the importance of phospholemman phosphorylation in the regulation of vascular tone and BP and suggest a novel mechanism, and therapeutic target, for aging-induced essential hypertension in humans.

Intracellular sodium elevation reprograms cardiac metabolism.

Intracellular Na elevation in the heart is a hallmark of pathologies where both acute and chronic metabolic remodelling occurs. Here, we assess whether acute (75 µM ouabain 100 nM blebbistatin) or chronic myocardial Nai load (PLM3SA mouse) are causally linked to metabolic remodelling and whether the failing heart shares a common Na-mediated metabolic 'fingerprint'. Control (PLMWT), transgenic (PLM3SA), ouabain-treated and hypertrophied Langendorff-perfused mouse hearts are studied by 23Na, 31P, 13C NMR followed by 1H-NMR metabolomic profiling. Elevated Nai leads to common adaptive metabolic alterations preceding energetic impairment: a switch from fatty acid to carbohydrate metabolism and changes in steady-state metabolite concentrations (glycolytic, anaplerotic, Krebs cycle intermediates). Inhibition of mitochondrial Na/Ca exchanger by CGP37157 ameliorates the metabolic changes. In silico modelling indicates altered metabolic fluxes (Krebs cycle, fatty acid, carbohydrate, amino acid metabolism). Prevention of Nai overload or inhibition of Na/Camito may be a new approach to ameliorate metabolic dysregulation in heart failure.

[Epidemiology of nasopharyngeal carriage of Streptococcus pneumoniae in children < 6 years old in Seville]. / Epidemiología de la colonización nasofaríngea por Streptococcus pneumoniae en niños menores de 6 años de la ciudad de Sevilla.

INTRODUCTION: The aim of this investigation was to study the epidemiology of nasopharyngeal (NP) colonization with Streptococcus pneumoniae after the introduction of the heptavalent pneumococcal conjugate vaccine (PCV7). METHODS: NP swabs were obtained from 848 children aged 6 months to six years seen in four primary care centres (healthy children) and in two emergency depeartments (sick children) from Seville. The study was conducted between February 2005 and June 2008. RESULTS: A total of 278 (33%) children carried S. pneumoniae. Pneumococcal colonization was independently predicted by school attendance or child care participation (OR 2.21; 95% CI 1.54- 3.15; P=.0001) and younger age. Recent antibiotic use was protective (OR 0.68; 95% CI 0.48-0.94; P=.02). PCV7 uptake was 41%. Risk of carriage of PCV7- type pneumococci was lower among children who had received ≥1 dose of PCV7 (7% vs 29%; [OR 0.21; 95% CI 0.09-0.49; P=.0001]). The proportion of pneumococcal isolates with oral penicillin non-susceptibility and amoxicillin resistance were 33% and 3%, respectively. Amoxicillin resistance in colonized children was associated with prior antibiotic usage (OR 4.29; 95% CI 1.09-20.02). CONCLUSIONS: NP colonization rates with PCV7- type pneumococci were low compared to those found in studies prior to PCV7 introduction, both in vaccinated and unvaccinated subjects. Factors related to age and overcrowding increased the prevalence of pneumococcal carriage. Use of antibiotics reduced the overall carriage of pneumococci, but was a risk factor for colonization with amoxicillin resistant pneumococci.

Pediatric parapneumonic empyema, Spain.

Pediatric parapneumonic empyema (PPE) has been increasing in several countries including Spain. Streptococcus pneumoniae is a major PPE pathogen; however, antimicrobial pretreatment before pleural fluid (PF) sampling frequently results in negative diagnostic cultures, thus greatly underestimating the contribution of pneumococci, especially pneumococci susceptible to antimicrobial agents, to PPE. The study aim was to identify the serotypes and genotypes that cause PPE by using molecular diagnostics and relate these data to disease incidence and severity. A total of 208 children with PPE were prospectively enrolled; blood and PF samples were collected. Pneumococci were detected in 79% of culture-positive and 84% of culture-negative samples. All pneumococci were genotyped by multilocus sequence typing. Serotypes were determined for 111 PPE cases; 48% were serotype 1, of 3 major genotypes previously circulating in Spain. Variance in patient complication rates was statistically significant by serotype. The recent PPE increase is principally due to nonvaccine serotypes, especially the highly invasive serotype 1.