Sickle cell anemia-associated pulmonary arterial hypertension

Clinical relevance of pulmonary vasculature involvement in sickle cell disease

Pulmonary complications are frequent in patients with sickle cell disease (SCD), but few studies have described lung pathology in SCD. We studied the lung tissue of 30 deceased SCD patients (1994-2012). Demographics, genotype, clinical characteristics, cause of death and associated conditions are presented. We quantified the presence of pulmonary arterial changes, thrombosis and venous thickening. Alveolar capillary abnormalities were demonstrated using CD34 expression and confocal microscopy. Autopsy and echocardiography reports were reviewed to classify heart abnormalities. Tissue expression of markers of endothelial activation (vascular cell adhesion molecule 1, intercellular adhesion molecule 1 and vascular endothelial growth factor) was quantified in pulmonary vessels. Median age was 33 years; genotype was SS in 19, SC in 7 and Sβ in 4, and there were 18 males. Hypertensive arterial changes were present in 76% of the patients, recent thrombosis in 80% and old thrombosis in 43%. Venous thickening was present in 23% and pulmonary capillary haemangiomatosis foci in 87%. Ten percent of the patients presented right ventricular hypertrophy. There was no increased expression of endothelial activation markers when compared to controls. SCD affects the whole pulmonary vascular tree and reflects the multiple burden on lung vasculature imposed by the disease upon time.

Left ventricular structural and functional changes evaluated by echocardiography and two-dimensional strain in patients with sickle cell disease

INTRODUCTION

Patients with sickle cell disease have increased left ventricular size, which is not usually accompanied by changes in systolic function indexes. We assessed echocardiographic abnormalities present in patients with sickle cell anemia (SCA) and compared echocardiographic parameters to other sickle cell diseases (OSCD).

MATERIAL AND METHODS

A blind cross-sectional study with 60 patients with SCA and 16 patients with OSCD who underwent transthoracic echocardiography was performed.

RESULTS

Echocardiographic findings were: left atrial volume index 47.7 ±11.5 ml/m² in SCA group and 31.7 ±8.42 ml/m² in OSCD group (p < 0.001); left ventricular diastolic diameter index 3.47 ±0.37 cm/m² in SCA group and 2.97 ±0.41 cm/m² in OSCD group (p < 0.001); left ventricular systolic diameter index 2.12 ±0.31 cm/m² in SCA group and 1.86 ±0.28 cm/m² in OSCD group (p < 0.001). There were no differences in the left ventricular ejection fraction: 68.2 ±6.69% in SCA group and 67.1 ±6.21% in OSCD group (p = 0.527). The ratio between mitral E wave and mean mitral annulus e' wave velocities was higher in the SCA group (7.72 ±1.54 vs. 6.70 ±1.65; p = 0.047). Mitral A wave correlated significantly with hemoglobin levels (r = -0.340; p = 0.032).

CONCLUSIONS

There was an increase of left ventricular and left atrial sizes in patients with SCA, compared to patients with OSCD, without changes in systolic or diastolic function in both groups. This could be due to the hyperkinetic state due to the more severe anemia in the SCA subjects.

Protection against monocrotaline-induced pulmonary arterial hypertension and caveolin-1 downregulation by fluvastatin in rats

Statins are Hydroxymethylglutaryl-coenzyme A reductase inhibitors, which are typically used to lower blood cholesterol. Additional beneficial effects, including improvement to pulmonary arterial hypertension (PAH), have also been confirmed. However, the mechanisms underlying this improvement have not yet been clarified. The present study was conducted to determine if fluvastatin was protective against experimental PAH development and to investigate the potential effects of fluvastatin on caveolin‑1 (cav‑1) expression. Rats were randomized to either receive a single subcutaneous injection of monocrotaline (MCT; 60 mg/kg; MCT group) or a single subcutaneous injection of MCT (60 mg/kg) followed by an oral gavage of fluvastatin (10 mg/kg) once daily until day 42 (M + F group). Rats in the MCT group received an equivalent volume of saline following the MCT injection. Six additional rats were given an equivalent volume of saline throughout as a control measure. PAH associated variables and cav‑1 protein expression were measured in each group at various times during the experimental period. Hemodynamic and morphometric analysis revealed that M + F rats developed moderate, delayed PAH. Cav‑1 western blot analysis demonstrated that cav‑1 expression was not significantly different in fluvastatin treated rats; however, MCT injured rats given saline had markedly reduced cav‑1 expression. It was concluded that fluvastatin may protect against PAH development and ameliorate MCT induced inhibition of cav‑1 expression in rats.

Cyclophosphamide improves engraftment in patients with SCD and severe organ damage who undergo haploidentical PBSCT

Peripheral blood stem cell transplantation (PBSCT) offers a curative option for sickle cell disease (SCD). Although HLA-matched sibling transplantation is promising, the vast majority of patients lack such a donor. We sought to develop a novel nonmyeloablative HLA-haploidentical PBSCT approach that could safely be used for patients with severe organ damage. Based on findings in our preclinical model, we developed a phase 1/2 trial using alemtuzumab, 400 cGy total body irradiation, and escalating doses of posttransplant cyclophosphamide (PT-Cy): 0 mg/kg in cohort 1, 50 mg/kg in cohort 2, and 100 mg/kg in cohort 3. A total of 21 patients with SCD and 2 with β-thalassemia received a transplant. The mean hematopoietic cell transplant-specific comorbidity index of 6 reflected patients with cirrhosis, heart failure, and end-stage renal disease. The engraftment rate improved from 1 (33%) of 3 in cohort 1 to 5 (63%) of 8 in cohort 2 and 10 (83%) of 12 in cohort 3. Percentage of donor myeloid and CD3 chimerism also improved with subsequent cohorts. There was no transplant-related mortality, and overall survival was 87%. At present, 0% in cohort 1, 25% in cohort 2, and 50% in cohort 3 remain free of their disease. There was no grade 2 to 4 acute or extensive chronic graft-versus-host disease (GVHD). Therefore, PT-Cy improves engraftment and successfully prevents severe GVHD after nonmyeloablative conditioning in patients with SCD who are at high risk for early mortality. Additional strategies are necessary to decrease the graft rejection rate and achieve a widely available cure for all patients with SCD. This trial was registered at www.clinicaltrials.gov as #NCT00977691.

Lung function and six-minute walk test performance in individuals with sickle cell disease

Background

Sickle Cell Disease (SCD), which is characterized by a mutation in the gene encoding beta hemoglobin, causes bodily dysfunctions such as impaired pulmonary function and reduced functional capacity.

Objective

To assess changes in pulmonary function and functional capacity in patients with SCD and to identify the relationships between these variables.

Method

We evaluated sociodemographic, anthropometric, lung function (spirometry), respiratory (manovacuometer), peripheral muscle strength (Handgrip strength - HS) and functional capacity (i.e., the six-minute walk test) parameters in 21 individuals with SCD (average age of 29±6 years). Shapiro-Wilk, paired Student's, Wilcoxon, Pearson and Spearman correlation tests were used for statistical analyses, and the significance threshold was set at p<0.05.

Results

A total of 47.6% of the study subjects exhibited an altered ventilation pattern, 42.8% had a restrictive ventilatory pattern (RVP) and 4.8% exhibited a mixed ventilatory pattern (MVP). The observed maximal inspiratory pressure (MIP) values were below the predicted values for women (64 cmH₂O), and the maximum expiratory pressure (MEP) values, HS values and distance walked during the 6MWT were below the predicted values for both men (103 cmH₂O, 39 Kgf and 447 m, respectively) and women (64 cmH₂O; 27 Kgf; 405 m, respectively). Positive correlations were observed between maximum voluntary ventilation (MVV) and MEP (r=0.4; p=0.046); MVV and BMI (r=0.6; p=0.003); and between HS and MIP (r=0.7; p=0.001), MEP (r=0.6; p=0.002), MVV (r=0.5; p=0.015), distance walked in the 6MWT (r=0.4; p=0.038) and BMI (r=0.6; p=0.004).

Conclusions

SCD promoted changes in lung function and functional capacity, including RVPs and a reduction in the distance walked in the 6MWT when compared to the predictions. In addition, significant correlations between the variables were observed.

A global perspective on the epidemiology of pulmonary hypertension

The epidemiology of pulmonary hypertension (PH) is not fully determined worldwide but is believed to vary in different regions of the world, with differences determined by genetic, geographic, environmental, and socioeconomic factors, as well as sex-related practices and inequities in access to health care. This article reviews the global epidemiology of PH, with emphasis on the prevalence, causes, forms, and underlying factors in the developing world. Left ventricular heart disease is the most common cause worldwide, but the main contributors in developing countries are chronic infectious diseases, hypertensive heart disease, cardiomyopathy, and rheumatic heart disease. Despite data suggesting a high prevalence in Sub-Saharan Africa, the available literature is very limited. International registries like the Pan African Pulmonary Hypertension Cohort are essential to provide information about the causes, comorbidities, and diagnostic classification, therapeutic management, and the natural course of PH worldwide. Moreover, there is a need to track diagnostic and management practices and challenges to identify the gaps and gradients between different regions of the world. The information gained will pinpoint areas for improvement, aiming at bridging the current divide between low-income and high-income countries.

A case of recurrent psychosis during sickle cell disease crisis treated successfully with ziprasidone

We present and follow a series of three consecutive hospitalizations of a 36-year-old, African-American male with sickle cell anemia disease who presented with sickle cell crises and a new onset psychotic episode. After multiple hospitalizations for prior episodes of sickle cell crisis-induced pain, treated with rehydration, blood transfusions, and opiate medication, this hospitalization was the first time he developed psychosis. As such, we discuss the differential diagnosis of the latter, and effective adjunctive treatment with ziprasidone.

A novel molecular signature for elevated tricuspid regurgitation velocity in sickle cell disease

RATIONALE

An increased tricuspid regurgitation jet velocity (TRV > 2.5 m/s) and pulmonary hypertension defined by right heart catheterization both independently confer increased mortality in sickle cell disease (SCD).

OBJECTIVES

We explored the usefulness of peripheral blood mononuclear cell-derived gene signatures as biomarkers for an elevated TRV in SCD.

METHODS

Twenty-seven patients with SCD underwent echocardiography and peripheral blood mononuclear cell isolation for expression profiling and 112 patients with SCD were genotyped for single-nucleotide polymorphisms.

MEASUREMENTS AND MAIN RESULTS

Genome-wide gene and miRNA expression profiles were correlated against TRV, yielding 631 transcripts and 12 miRNAs. Support vector machine analysis identified a 10-gene signature including GALNT13 (encoding polypeptide N-acetylgalactosaminyltransferase 13) that discriminates patients with and without increased TRV with 100% accuracy. This finding was then validated in a cohort of patients with SCD without (n = 10) and with pulmonary hypertension (n = 10, 90% accuracy). Increased TRV-related miRNAs revealed strong in silico binding predictions of miR-301a to GALNT13 corroborated by microarray analyses demonstrating an inverse correlation between their expression. A genetic association study comparing patients with an elevated (n = 49) versus normal (n = 63) TRV revealed five significant single-nucleotide polymorphisms within GALNT13 (P < 0.005), four trans-acting (P < 2.1 × 10(-7)) and one cis-acting (P = 0.6 × 10(-4)) expression quantitative trait locus upstream of the adenosine-A2B receptor gene (ADORA2B).

CONCLUSIONS

These studies validate the clinical usefulness of genomic signatures as potential biomarkers and highlight ADORA2B and GALNT13 as potential candidate genes in SCD-associated elevated TRV.

Sickle cell disease and venous thromboembolism

Hemoglobin S in homozygous state or in combination with one of the structural variants of Hb D-Punjab, Hb O-Arab, Hb C or β-thalassemia mutation results in sickle cell disease (SCD) that is characterized by chronic hemolytic anemia and tissue injury secondary to vasooclusion. A chronic hypercoagulable state in SCD has been established with the increased risk of thromboembolic complications in these patients. The goal of present review is to survey of the literature related to thromboembolic events and genetic risk factors involved in the manifestation of these events in SCD patients with focus on studies from Mediterranean countries. Also, this review covers the pathogenesis of hypercoagulability and alteration in the components of hemostasis system.

Função pulmonar em portadores de anemia falciforme

OBJETIVO: Avaliar a função ventilatória por meio de espirometria, em escolares e adolescentes com anemia falciforme (AF), relacionando os achados a parâmetros clínicos e hematológicos. MÉTODOS: Foram avaliados portadores de AF de ambos os gêneros, a partir dos dez anos, clinicamente estáveis, sem intercorrências agudas, que foram submetidos à espirometria e avaliados quanto à saturação transcutânea de oxigênio, níveis de hemoglobina e contagem de leucócitos. Verificou-se a associação de alterações à espirometria com as características demográficas, clínicas e laboratoriais dos pacientes analisados. Para a análise estatística, aplicou-se o teste do qui-quadrado e o teste t para amostras não pareadas, sendo significante p<0,05. RESULTADOS: Foram estudados 51 pacientes e, em 40 (78%), identificou-se comprometimento do perfil espirométrico, do quais 20 (50%) apresentaram distúrbio ventilatório misto ou combinado, 13 (33%) mostraram perfil restritivo clássico e sete (18%), distúrbio ventilatório obstrutivo. Dos sete, em cinco (71%) observou-se resposta broncodilatadora positiva. A contagem total de leucócitos associou-se à função pulmonar alterada. O volume expiratório forçado no primeiro segundo sem broncodilatador, a capacidade vital forçada antes e após broncodilatador e o fluxo expiratório forçado entre 25 e 75% da capacidade vital forçada após broncodilatador foram significativamente menores nos pacientes com relato de internação hospitalar prévia por doença pulmonar aguda. CONCLUSÕES: A maioria dos pacientes apresentou alteração da função pulmonar, predominando o padrão misto ou combinado, seguido pelo restritivo clássico. Presença de leucocitose, na ausência de intercorrências agudas, associou-se a comprometimento de função pulmonar.

Resting blood lactate in individuals with sickle cell disease

BACKGROUND

The most common hereditary hemoglobin disorder, affecting 20 million individuals worldwide, is sickle cell disease. The vascular obstruction resulting from the sickling of cells in this disease can produce local hypoxemia, pain crises and infarction in several tissues, including the bones, spleen, kidneys and lungs.

OBJECTIVE

To determine red blood group genes in a Brazilian populations.

METHODS

The present study is characterized as a case control study, with the aim of identifying the baseline blood lactate concentration in individuals with hemoglobin SS and SC diseases. One-way ANOVA with the Tukey post-test was used to analyze the results and a p-value < 0.05 was considered significant. Calculations were made using the INSTAT statistical program. The graphs were generated using the ORING program. The study sample was composed of 31 men and women residing in the city of Santo Antônio de Jesus, Bahia, Brazil. The individuals were divided into two groups: Group GC of 16 subjects who did not present with any type of structural hemoglobinopathy; and Group GE composed of 15 individuals with ages between 2 and 35 years old, who had the SS and SC genotypes. Sample analyses were performed with 3 mL of blood during fasting.

RESULTS

The baseline blood lactate concentration of the SS and SC individuals was higher than that of the control group (p<0.001) with means of 4.86 ± 0.95; 3.30 ± 0.33; 1.31 ± 0.08 IU/L for SS, SC and controls, respectively. This corroborates the initial research hypothesis.

CONCLUSION

The baseline blood lactate of SS and SC individuals is 3 to 4 times higher than that of healthy subjects, probably due to the fact that these patients have a metabolic deviation to the anaerobic pathway.

Prevalence of obstructive sleep apnea in children and adolescents with sickle cell anemia

OBJECTIVE

To estimate the prevalence of obstructive sleep apnea syndrome (OSAS) in children and adolescents with sickle cell anemia (SCA); to investigate the possible correlation between mean annual hemoglobin level and total sleep time with SpO2 < 90%, as well as between mean annual hemoglobin level and total sleep time with SpO2 < 80%; and to investigate the possible correlation between apnea-hypopnea index (AHI) and painful crisis.

METHODS

The study involved 85 patients with SCA. The patients completed a questionnaire, were submitted to polysomnography and underwent clinical evaluation (by a pediatrician and an otolaryngologist). An AHI > 1 was considered indicative of a diagnosis of OSAS.

RESULTS

The prevalence of OSAS was 10.6%. We found a negative correlation between mean annual hemoglobin level and total sleep time with SpO2 < 90% (r = micro0.343; p = 0.002), as well as between mean annual hemoglobin level and total sleep time with SpO2 < 80% (r = micro0.270; p = 0.016). There was no association between AHI and painful crisis.

CONCLUSIONS

The prevalence of OSAS in this population was high (10.6%). Therefore, it is important to identify signs of OSAS as soon as possible and to determine the mean annual hemoglobin level because of the inverse correlation between that level and the total sleep time with SpO2 < 90% or < 80%.