Laura Gutierrez

Haploinsufficiency for the erythroid transcription factor KLF1 causes hereditary persistence of fetal hemoglobin

Hereditary persistence of fetal hemoglobin (HPFH) is characterized by persistent high levels of fetal hemoglobin (HbF) in adults. Several contributory factors, both genetic and environmental, have been identified but others remain elusive. HPFH was found in 10 of 27 members from a Maltese family. We used a genome-wide SNP scan followed by linkage analysis to identify a candidate region on chromosome 19p13.12–13. Sequencing revealed a nonsense mutation in the KLF1 gene, p.K288X, which ablated the DNA-binding domain of this key erythroid transcriptional regulator. Only family members with HPFH were heterozygous carriers of this mutation. Expression profiling on primary erythroid progenitors showed that KLF1 target genes were downregulated in samples from individuals with HPFH. Functional assays suggested that, in addition to its established role in regulating adult globin expression, KLF1 is a key activator of the BCL11A gene, which encodes a suppressor of HbF expression. These observations provide a rationale for the effects of KLF1 haploinsufficiency on HbF levels.

Hemopoietic cell expression of the chemokine decoy receptor D6 is dynamic and regulated by GATA1

D6 scavenges inflammatory chemokines and is essential for the regulation of inflammatory and immune responses. Mechanisms explaining the cellular basis for D6 function have been based on D6 expression by lymphatic endothelial cells. In this study, we demonstrate that functional D6 is also expressed by murine and human hemopoietic cells and that this expression can be regulated by pro- and anti-inflammatory agents. D6 expression was highest in B cells and dendritic cells (DCs). In myeloid cells, LPS down-regulated expression, while TGF-beta up-regulated expression. Activation of T cells with anti-CD3 and soluble CD28 up-regulated mRNA expression 20-fold, while maturation of human macrophage and megakaryocyte precursors also up-regulated D6 expression. Competition assays demonstrated that chemokine uptake was D6 dependent in human leukocytes, whereas mouse D6-null cells failed to uptake and clear inflammatory chemokines. Furthermore, we present evidence indicating that D6 expression is GATA1 dependent, thus explaining D6 expression in myeloid progenitor cells, mast cells, megakaryocytes, and DCs. We propose a model for D6 function in which leukocytes, within inflamed sites, activate D6 expression and thus trigger resolution of inflammatory responses. Our data on D6 expression by circulating DCs and B cells also suggest alternative roles for D6, perhaps in the coordination of innate and adaptive immune responses. These data therefore alter our models of in vivo D6 function and suggest possible discrete, and novel, roles for D6 on lymphatic endothelial cells and leukocytes.

A novel flow cytometry-based platelet aggregation assay

The main function of platelets is to maintain normal hemostasis. Inefficient platelet production and/or defective platelet function results in bleeding disorders resulting from a wide range of genetic traits and acquired pathologies. Several platelet function tests have been developed for use in the clinic and in experimental animal models. In particular, platelet aggregation is routinely measured in an aggregometer, which requires normal platelet counts and significant blood sample volumes. For this reason, the analysis of thrombocytopenic patients, infants, and animal models is problematic. We have developed a novel flow cytometry test of platelet aggregation, in which 10- to 25-fold lower platelet counts or sample volumes can be used, either of platelet-rich plasma or whole blood from human subjects or mice. This setup can be applied to test in small assay volumes the influence of a variety of stimuli, drugs, and plasma factors, such as antibodies, on platelet aggregation. The presented principle stands as a novel promising tool, which allows analysis of platelet aggregation in thrombocytopenic patients or infants, and facilitates studies in platelets obtained from experimental animal models without the need of special devices but a flow cytometer.

Development of blood transfusion product pathogen reduction treatments: A review of methods, current applications and demands

Transfusion-transmitted infections (TTI) have been greatly reduced in numbers due to the strict donor selection and screening procedures, i.e. the availability of technologies to test donors for endemic infections, and routine vigilance of regulatory authorities in every step of the blood supply chain (collection, processing and storage). However, safety improvement is still a matter of concern because infection zero-risk in transfusion medicine is non-existent. Alternatives are required to assure the safety of the transfusion product and to provide a substitution to systematic blood screening tests, especially in less-developed countries or at the war-field. Furthermore, the increasing mobility of the population due to traveling poses a new challenge in the endemic screening tests routinely used, because non-endemic pathogens might emerge in a specific population. Pathogen reduction treatments sum a plethora of active approaches to eliminate or reduce potential threatening pathogen load from blood transfusion products. Despite the success of pathogen reduction treatments applied to plasma products, there is still a long way to develop and deploy pathogen reduction treatments to cellular transfusion products (such as platelets, RBCs or even to whole blood) and there is divergence on its acceptance worldwide. While the use of pathogen reduction treatments in platelets is performed routinely in a fair number of European blood banks, most of these treatments are not (or just) licensed in the USA or elsewhere in the world. The development of pathogen reduction treatments for RBC and whole blood is still in its infancy and under clinical trials. In this review, we discuss the available and emerging pathogen reduction treatments and their advantages and disadvantages. Furthermore, we highlight the importance of characterizing standard transfusion products with current and emerging approaches (OMICS) and clinical outcome, and integrating this information on a database, thinking on the benefits it might bring in the future toward personalized transfusion therapies.

Btk is required for an efficient response to erythropoietin and for SCF-controlled protection against TRAIL in erythroid progenitors.

Regulation of survival, expansion, and differentiation of erythroid progenitors requires the well-controlled activity of signaling pathways induced by erythropoietin (Epo) and stem cell factor (SCF). In addition to qualitative regulation of signaling pathways, quantitative control may be essential to control appropriate cell numbers in peripheral blood. We demonstrate that Brutons tyrosine kinase (Btk) is able to associate with the Epo receptor (EpoR) and Jak2, and is a substrate of Jak2. Deficiency of Btk results in reduced and delayed phosphorylation of the EpoR, Jak2, and downstream signaling molecules such as Stat5 and PLCγ1 as well as in decreased responsiveness to Epo. As a result, expansion of erythroid progenitors lacking Btk is impaired at limiting concentrations of Epo and SCF. In addition, we show that SCF induces Btk to interact with TNF-related apoptosis-inducing ligand (TRAIL)–receptor 1 and that lack of Btk results in increased sensitivity to TRAIL-induced apoptosis. Together, our results indicate that Btk is a novel, quantitative regulator of Epo/SCF-dependent expansion and survival in erythropoiesis.

Multiple cardiometabolic risk factors in the Southern Cone of Latin America: A population-based study in Argentina, Chile, and Uruguay

Background Cardiovascular disease is a major cause of death, and its mortality is increasing in Latin America. However, population-based data on cardiovascular disease risk factors are sparse in these countries. Methods A total of 7,524 men and women, aged 35 to 74 years old, were recruited between February 2010 and December 2011 from randomly selected samples in 4 cities (Bariloche and Marcos Paz, Argentina; Temuco, Chile; and Pando-Barros Blancos, Uruguay) in the Southern Cone of Latin America. Cardiovascular risk factors were measured using standard methods by trained and certified observers. Results Approximately 85.5% of adults ate less than five servings of fruit or vegetables per day, 35.2% engaged in low physical activity, and 29.7% currently smoked cigarettes. The prevalences of obesity, central obesity, hypertension, chronic kidney disease, dyslipidemia, diabetes, and metabolic syndrome were 35.7%, 52.9%, 40.8%, 2.0%, 58.4%, 12.4%, and 37.4%, respectively. The proportion of individuals with ≥3 cardiovascular risk factors, including low intake of fruit and vegetables, low physical activity, current cigarette smoking, obesity or central obesity, hypertension, chronic kidney disease, dyslipidemia, and diabetes, was 68.3%, and the proportion of individual with ≥3 cardiometabolic risk factors, including obesity or central obesity, hypertension, chronic kidney disease, dyslipidemia, and diabetes, was 22.9%. Conclusions Cardiovascular disease risk factors are highly prevalent in the general population in the Southern Cone of Latin America. These data suggest that national efforts on the prevention, treatment, and control of cardiovascular risk factors should be a public health priority in the Southern Cone of Latin America.

Effectiveness of an mHealth intervention to improve the cardiometabolic profile of people with prehypertension in low-resource urban settings in Latin America: a randomised controlled trial

BACKGROUNDnPoor diet and physical inactivity strongly affect the growing epidemic of cardiovascular disease worldwide. Mobile phone-based health interventions (mHealth) have been shown to help promote weight loss and increase physical activity and are an attractive approach for health-care systems with limited resources. We aimed to assess whether mHealth with advice for lifestyle improvements would reduce blood pressure, promote weight loss, and improve diet quality and physical activity in individuals with prehypertension living in low-resource urban settings in Latin America.nnnMETHODSnIn this parallel-group, randomised controlled trial, we recruited individuals (aged 30-60 years) with systolic blood pressure between 120 and 139 mm Hg, diastolic blood pressure between 80 and 89 mm Hg, or both from health-care centres, workplaces, and community centres in low-resource urban settings in Argentina, Guatemala, and Peru. Participants were randomly assigned to receive either monthly motivational counselling calls and weekly personalised text messages to their mobile phones about diet quality and physical activity for 12 months, or usual care. Randomisation was stratified by country, and we applied minimisation by sex and age groups. Study personnel collecting and analysing data were masked to group assignment. The primary outcomes were mean between-group differences in the changes in systolic and diastolic blood pressure from baseline to 12 months in an intention-to-treat analysis of all participants who completed assessments at 12 months. Secondary outcome measures were changes in bodyweight, waist circumference, and self-reported target behaviours from baseline to 12 months. The trial is registered with ClinicalTrials.gov, number NCT01295216.nnnFINDINGSnBetween March 1, 2012, and Nov 30, 2012, we randomly assigned 637 participants to receive intervention (n=316) or usual care (n=321). 266 (84%) participants in the intervention group and 287 (89%) in the control group were assessed at 12 months. The intervention did not affect change in systolic blood pressure (mean net change -0·37 mm Hg [95% CI -2·15 to 1·40]; p=0·43) or diastolic blood pressure (0·01 mm Hg [-1·29 to 1·32]; p=0·99) compared with usual care. However, we noted a significant net reduction in bodyweight (-0·66 kg [-1·24 to -0·07]; p=0·04) and intake of high-fat and high-sugar foods (-0·75 [-1·30 to -0·20]; p=0·008) in the intervention group compared with the control group. In a prespecified subanalysis, we found that participants in the intervention group who received more than 75% of the calls (nine or more, from a maximum of 12) had a greater reduction of bodyweight (-4·85 [-8·21 to -1·48]) and waist circumference (-3·31 [-5·95 to -0·67]) than participants in the control group. Additionally, participants in the intervention group had an increase in the intake of fruits and vegetables and a decrease in diets high in sodium, fat, and simple sugars relative to participants in the control group. However, we found no changes in systolic blood pressure, diasatolic blood pressure, or physical activity in the group of participants who received more than 75% of the calls compared with the group who received less than 50% of the calls.nnnINTERPRETATIONnOur mHealth-based intervention did not result in a change in blood pressure that differed from usual care, but was associated with a small reduction in bodyweight and an improvement in some dietary habits. We noted a dose-response effect, which signals potential opportunities for larger effects from similar interventions in low-resource settings. More research is needed on mHealth, particularly among people who are poor and disproportionally affected by the cardiovascular disease epidemic and who need effective and affordable interventions to help bridge the equity gap in the management of cardiometabolic risk factors.nnnFUNDINGnNational Heart, Lung, and Blood Institute (US National Institutes of Health) and the Medtronic Foundation.

Daily sodium consumption and CVD mortality in the general population: systematic review and meta-analysis of prospective studies

OBJECTIVEnThe purpose of the present study was to determine whether elevated dietary Na intake could be associated with CVD mortality.nnnDESIGNnWe performed a systematic review and meta-analysis of prospective studies representing the general population. The adjusted relative risks and their 95 % confidence intervals were pooled by the inverse variance method using random-effects models. Heterogeneity, publication bias, subgroup and meta-regression analyses were performed. Settings MEDLINE (since 1973), Embase (since 1975), the Cochrane Library (since 1976), ISI Web of Science, Google Scholar (until September 2013) and secondary referencing were searched for inclusion in the study. Subject Eleven prospective studies with 229 785 participants and average follow-up period of 13.37 years (range 5.5-19 years).nnnRESULTSnHigher Na intake was significantly associated with higher CVD mortality (relative risk=1.12; 95 % CI 1.06, 1.19). In the sensitivity analysis, the exclusion of studies with important relative weights did not significantly affect the results (relative risk=1.08; 95 % CI 1.01, 1.15). The meta-regression analysis showed that for every increase of 10 mmol/d in Na intake, CVD mortality increased significantly by 1 % (P=0.016). Age, hypertensive status and length of follow-up were also associated with increased CVD mortality.nnnCONCLUSIONSnHigher Na intake was associated with higher CVD mortality in the general population; this result suggests a reduction in Na intake to prevent CVD mortality from any cause.

Hypertension Prevalence, Awareness, Treatment, and Control in Selected LMIC Communities Results From the NHLBI/UHG Network of Centers of Excellence for Chronic Diseases

BACKGROUNDnHypertension is the leading cause of cardiovascular disease and premature death worldwide. The prevalence of this public health problem is increasing in low- and middle-income countries (LMICs) in both urban and rural communities.nnnOBJECTIVEnThe aim of this study was to examine hypertension prevalence, awareness, treatment, and control in adults 35 to 74 years of age from urban and rural communities in LMICs in Africa, Asia, and South America.nnnMETHODSnThe authors analyzed data from 7 population-based cross-sectional studies in selected communities in 9 LMICs that were conducted between 2008 and 2013. Age- and sex-standardized prevalence rates of pre-hypertension and hypertension were calculated. The prevalence rates of awareness, treatment, and control of hypertension were estimated overall and by subgroups of age, sex, and educational level.nnnRESULTSnIn selected communities, age- and sex-standardized prevalence rates of hypertension among men and women 35 to 74 years of age were 49.9% (95% confidence interval [CI]: 42.3% to 57.4%) in Kenya, 54.9% (95% CI: 51.3% to 58.4%) in South Africa, 52.5% (95% CI: 50.1% to 54.8%) in China, 32.5% (95% CI: 31.7% to 33.3%) in India, 42.3% (95% CI: 40.4% to 44.2%) in Pakistan, 45.4% (95% CI: 43.6% to 47.2%) in Argentina, 39.9% (95% CI: 37.8% to 42.1%) in Chile, 19.2% (95% CI: 17.8% to 20.5%) in Peru, and 44.1% (95% CI: 41.6% to 46.6%) in Uruguay. The proportion of awareness varied from 33.5% in India to 69.0% in Peru, the proportion of treatment among those who were aware of their hypertension varied from 70.8% in South Africa to 93.3% in Pakistan, and the proportion of blood pressure control varied from 5.3% in China to 45.9% in Peru.nnnCONCLUSIONSnThe prevalence of hypertension varies widely in different communities. The rates of awareness, treatment, and control also differ in different settings. There is a clear need to focus on increasing hypertension awareness and control in LMICs.

Pathogen reduction treatment using riboflavin and ultraviolet light impairs platelet reactivity toward specific agonists in vitro.

Recent studies showed that Mirasol pathogen reduction treatment (PRT) leads to increased P‐selectin expression and increased oxygen and glucose consumption in resting platelets (PLTs). This study investigates the effect of PRT on PLT activation.