Detection of the mRNA Transcription Level of Several Genes of the HIF and NO Metabolic Pathways in PBMCs of Sickle Cell Disease Patients Using Quantitative RT-PCR Assay.

Abstract Background. Pulmonary hypertension is a common complication of sickle cell disease but the pathophysiology is not completely understood. Methods. Using quantitative RT-PCR we studied mRNA from PBMCs of seven patients with sickle cell disease having pulmonary hypertension, five patients without pulmonary hypertension and 10 controls with neither sickle cell disease nor pulmonary hypertension. We investigated transcripts of several HIF regulated genes including endothelin-1 (ET1), vascular endothelial growth factor (VEGF), and inducible nitric oxide synthase (iNOS), several genes of the NO metabolic pathway including cGMP-specific phosphodiesterase 5A (PDE5), soluble guanylate cyclase large subunit (sGC), and arginase 2 (Arg2), and a gene implicated in primary pulmonary hypertension, bone morphogenetic protein receptor type II (BMPR2). β-actin and diacylglycerol kinase alpha (DGKA) were used as housekeeping gene controls. Results. HIF-regulated genes: Levels of ET1 transcripts were higher in patients with sickle cell disease and pulmonary hypertension than the other two groups while VEGF transcripts were higher in both sickle cell disease groups than controls and levels of iNOS transcripts were low and did not differ among the groups. Upregulation of ET1 is associated with the development of hypoxic pulmonary hypertension in both experimental animals and humans. NO pathway genes: PDE5, sGC, Arg2 transcripts were higher in patients with sickle cell disease and PH than the other two groups. Upregulation of PDE5 and Arg2 might be expected to contribute to reduced NO signaling. Primary pulmonary hypertension gene: BMPR2 transcripts were higher in patients with sickle cell disease and PH than the other two groups. Discussion. These results are consistent with the possibility that complex molecular pathways, including dysregulation of HIF and NO pathways, may contribute to the development of pulmonary hypertension in sickle cell disease.

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Pregnancy Outcomes in Systemic Sclerosis, Primary Pulmonary Hypertension, and Sickle Cell Disease

Yearbook of Pulmonary Disease ◽

10.1016/s8756-3452(08)79094-7 ◽

2009 ◽

Vol 2009 ◽

pp. 196-197

Author(s):

M. Ali Raza

Keyword(s):

Pulmonary Hypertension ◽

Systemic Sclerosis ◽

Sickle Cell Disease ◽

Sickle Cell ◽

Pregnancy Outcomes ◽

Primary Pulmonary Hypertension ◽

Cell Disease

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Lack of Clustering of SCD Complications Into Two Distinct Subphenotypes In An Adult Patient Population.

Blood ◽

10.1182/blood.v116.21.1643.1643 ◽

2010 ◽

Vol 116 (21) ◽

pp. 1643-1643 ◽

Cited By ~ 1

Author(s):

Jigarkumar Parikh ◽

Thomas Kochaparambil ◽

Hongyan Xu ◽

Betsy Clair ◽

Kavita Natarajan ◽

...

Keyword(s):

Pulmonary Hypertension ◽

Endothelial Dysfunction ◽

Sickle Cell Disease ◽

Sickle Cell ◽

Principal Components ◽

The Other ◽

Leg Ulcers ◽

Cell Disease ◽

Factor Map ◽

Pathophysiologic Mechanisms

Abstract Abstract 1643 The complex pathophysiologic mechanisms that contribute to disease pathology in sickle cell disease (SCD) include microvascular occlusion secondary to deoxy-Hb S polymerization, interaction of sickle RBCs with vascular endothelium and other blood cells, hemolysis with resultant nitric oxide (NO) scavenging, endothelial activation with inflammation, and activation of coagulation. It has been recently hypothesized that there may be two distinct sub-phenotypes in SCD: one where hemolysis and NO depletion predominates (hemolysis/endothelial dysfunction) and the other where vaso-occlusion and increased whole blood viscosity plays a more prominent role. The clinical complications of SCD thus cluster into one of the two subphenotypes: pulmonary hypertension, priapism, leg ulcers and stroke appear to be more commonly associated with the hemolysis/NO depletion/endothelial dysfunction subphenotype, whereas frequent pain episodes, acute chest syndrome, osteonecrosis and retinopathy tend to be more common in the viscosity/vaso-occlusion group. We had previously analyzed the records of 124 patients with Hb SS or S-b° thalassemia followed at the Medical College of Georgia Adult Sickle Cell Clinic to validate the clustering of disease complications into the aforementioned two sub-phenotypes and found no significant associations between phenotypes within each sub-group, as well as between phenotypes across the groups (all p values >0.1). The following criteria were used to define complications: We have now extended our analyses to 203 patients with Hb SS or S-b° thalassemia (ages 12–60; 101 males, 102 females). We performed principal component analysis on the data from 203 patients. A total of 10 sub-phenotype variables were used in the analysis. The variables are VOE, ACS, retinopathy, gallstones, AVN, stroke, nephropathy, pulmonary hypertension, leg ulcers, and priapism. The individual factor map based on the first 2 principal components is shown below. Each dot represents a patient in the figure. If the hypothesis of two groups of sub-phenotypes were correct, we would see two clusters of patients. However, from this figure, there is no clear clustering of patients. We also plotted the sub-phenotype variables factor map based on the results from the principal components analysis. As shown in the following figure, the sub-phenotypes are not clustered into two groups as predicted by the hypothesis. In particular, we have retinopathy in one extreme and gallstones in the other. They are not clustered in one group. Our results indicate that the complications of sickle cell disease do not cluster into two distinct subphenotypes as previously hypothesized. While this hypothesis may provide a useful conceptual framework in deconstructing and understanding various pathophysiologic mechanisms operative in sickle cell disease, such clear cut distinction is not applicable in clinical practice. Disclosures: No relevant conflicts of interest to declare.

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