[Show abstract][Hide abstract] ABSTRACT: thalassemia major (TM) patients experience iron overload and hemolysis resulting in oxidative stress, chronic inflammation and an increased risk for infection. Monocytes of the innate immune system rely on pattern recognition receptors (PRR; e.g., toll-like receptor 4 [TLR4]) to provide defense against pathogens. Recently, PRR ligands have been found to include damage-associated molecular patterns (DAMPs). We hypothesize that increased iron and heme will generate reactive oxygen species (ROS) that induce lipid peroxidation creating malondialdehyde (MDA) and the DAMP 4-hydroxynonenal (4-HNE) that will modulate monocyte TLR4 activity. We cultured THP-1 monocytic cells with increasing concentrations of ferric citrate, heme, or 4-HNE for 24 hours to model iron overloaded monocytes of TM. ROS and TLR4 expression were quantified using flow cytometry while MDA and IL-6 were measured using a colorimetric assay and ELISA. The THP-1 model was compared to peripheral blood monocytes (PBM) from 13 TM patients. Exposure of THP-1 cells to iron resulted in a dose-dependent formation of ROS, whereas only high concentrations of heme generated ROS (p < 0.001 and p = 0.060). Conversely, heme induced a dose-response generation of MDA but only high concentrations of ferric iron increased MDA production (p < 0.0001 and p = 0.278). 4-HNE added to the culture media negatively correlated to IL-6 production (r = -0.94, p = 0.018). Lastly, larger more granular THP-1 cells expressed more TLR4 and ROS than smaller less granular cells (p < 0.001). PBMs from TM patients displayed a similar TLR4 heterogenic pattern. Our in vitro model demonstrates how iron and heme stimulate production of ROS and MDA, while DAMPs like 4-HNE inhibit TLR4, reducing Il-6 production. Finally, we identified a novel sub-population of monocytic cells that appear to be greater contributors to the inflammatory response.
[Show abstract][Hide abstract] ABSTRACT: MRM proteomics was used to investigate the systemic state of iron trafficking, OS and inflammation in an NBIA patient with PLA2G6 Associated Neurodegeneration (PLAN). Patients with PLAN show progressive Parkinsonism and dystonia and are characterized by abnormal iron accumulation and increased OS and inflammation in the Substantia Nigra (SN).Plasma samples were obtained from a patient with a heterozygous mutation in the PLA2G6 gene and a matched control. MRM is a mass spectrometry technique that can be applied to accurately measure a large number of target proteins in a sample such as plasma. For this pilot trial we used MRM to measure proteins of inflammation (Lipocalin-2), OS (glutathione peroxidase (GP)) and iron trafficking (hemopexin, ceruloplasmin, transferrin(Tf) and soluble transferrin receptor(STf)). Additional measurements of the OS markers malondialdehyde (MDA) and 4-Hydroxynonenal (4-HNE) and the inflammatory markers IL-6 and c-reactive protein (CRP) were also performed. Proteomic analysis revealed that the PLAN patient had a 129% increase in the expression of the heme trafficking proteins haptoglobin and 39% increase in the ferroxidase ceruloplasmin relative to a healthy control. Tf expression was decreased by 26%, but STf expression increased 47% relative to the control. A marker of inflammation, Lipocalin-2 was increased 62% and the antioxidant protein GP was increased by 14% relative to the control. These proteomic changes in OS and inflammation were confirmed by a 78% increase in MDA and a 4-fold increase in 4-HNE and IL-6 compared to that of the control as well as a CRP of 4.0. MRM proteomic analysis showed changes in the expression of iron trafficking proteins and increased systemic OS and inflammation in the patient. This preliminary pilot trial showed that MRM has the potential to identify disease biomarkers in NBIA patients. Expanded biomarker analysis of NBIA patients using MRM is ongoing.
[Show abstract][Hide abstract] ABSTRACT: This study was conducted to determine the relationship of frontal lobe cortical thickness and basal ganglia volumes to measures of cognition in adults with sickle cell anemia (SCA).
Participants included 120 adults with SCA with no history of neurologic dysfunction and 33 healthy controls (HCs). Participants were enrolled at 12 medical center sites, and raters were blinded to diagnostic group. We hypothesized that individuals with SCA would exhibit reductions in frontal lobe cortex thickness and reduced basal ganglia and thalamus volumes compared with HCs and that these structural brain abnormalities would be associated with measures of cognitive functioning (Wechsler Adult Intelligence Scale, 3rd edition).
After adjusting for age, sex, education level, and intracranial volume, participants with SCA exhibited thinner frontal lobe cortex (t = -2.99, p = 0.003) and reduced basal ganglia and thalamus volumes compared with HCs (t = -3.95, p < 0.001). Reduced volume of the basal ganglia and thalamus was significantly associated with lower Performance IQ (model estimate = 3.75, p = 0.004) as well as lower Perceptual Organization (model estimate = 1.44, p = 0.007) and Working Memory scores (model estimate = 1.37, p = 0.015). Frontal lobe cortex thickness was not significantly associated with any cognitive measures.
Our findings suggest that basal ganglia and thalamus abnormalities may represent a particularly salient contributor to cognitive dysfunction in adults with SCA.
[Show abstract][Hide abstract] ABSTRACT: Silent cerebral infarct (SCI) is the most common form of neurologic disease in children with sickle cell anemia (SCA). SCI is defined as abnormal magnetic resonance imaging (MRI) of the brain in the setting of a normal neurologic examination without a history or physical findings associated with an overt stroke. SCI occurs in 27% of this population before their sixth, and 37% by their 14th birthdays. In adults with SCA, the clinical history of SCI is poorly defined, although recent evidence suggests that they too may have ongoing risk of progressive injury. Risk factors for SCI include male sex, lower baseline hemoglobin concentration, higher baseline systolic blood pressure, and previous seizures. Specific morbidity associated with SCI includes a decrement in general intellectual abilities, poor academic achievement, progression to overt stroke, and progressive SCI. In addition, children with previous stroke continue to have both overt strokes and new SCI despite receiving regular blood transfusion therapy for secondary stroke prevention. Studies that only include overt stroke as a measure of CNS injury significantly underestimate the total cerebral injury burden in this population. In this review, we describe the epidemiology, natural history, morbidity, medical management, and potential therapeutic options for SCI in SCA.
[Show abstract][Hide abstract] ABSTRACT: Renal papillary necrosis in sickling hemoglobinopathies can lead to significant complications, including hemorrhage, obstruction, and infection. Despite its frequency, there are limited therapies for protracted hemorrhage. In the past, massive hemorrhage was managed with nephrectomy. Here, we report a patient with hemoglobin SC disease and prolonged, life-threatening hemorrhage from papillary necrosis successfully treated with oral, low-dose epsilon aminocaproic acid (EACA). Although further study is warranted, this case illustrates the need to consider EACA in the conservative management of renal papillary necrosis and significant hemorrhage in sickle cell hemoglobinopathies.
No preview · Article · Jan 2010 · Pediatric Blood & Cancer
[Show abstract][Hide abstract] ABSTRACT: Adults with beta thalassemia major frequently have low BMD, fractures, and bone pain. The purpose of this study was to determine the prevalence of low BMD, fractures, and bone pain in all thalassemia syndromes in childhood, adolescence, and adulthood, associations of BMD with fractures and bone pain, and etiology of bone disease in thalassemia. Patients of all thalassemia syndromes in the Thalassemia Clinical Research Network, > or =6 yr of age, with no preexisting medical condition affecting bone mass or requiring steroids, participated. We measured spine and femur BMD and whole body BMC by DXA and assessed vertebral abnormalities by morphometric X-ray absorptiometry (MXA). Medical history by interview and review of medical records, physical examinations, and blood and urine collections were performed. Three hundred sixty-one subjects, 49% male, with a mean age of 23.2 yr (range, 6.1-75 yr), were studied. Spine and femur BMD Z-scores < -2 occurred in 46% and 25% of participants, respectively. Greater age, lower weight, hypogonadism, and increased bone turnover were strong independent predictors of low bone mass regardless of thalassemia syndrome. Peak bone mass was suboptimal. Thirty-six percent of patients had a history of fractures, and 34% reported bone pain. BMD was negatively associated with fractures but not with bone pain. Nine percent of participants had uniformly decreased height of several vertebrae by MXA, which was associated with the use of iron chelator deferoxamine before 6 yr of age. In patients with thalassemia, low BMD and fractures occur frequently and independently of the particular syndrome. Peak bone mass is suboptimal. Low BMD is associated with hypogonadism, increased bone turnover, and an increased risk for fractures.
Full-text · Article · Mar 2009 · Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research
[Show abstract][Hide abstract] ABSTRACT: Senicapoc, a novel Gardos channel inhibitor, limits solute and water loss, thereby preserving sickle red blood cell (RBC) hydration. Because hemoglobin S polymerization is profoundly influenced by intracellular hemoglobin concentration, senicapoc could improve sickle RBC survival. In a 12-week, multicenter, phase 2, randomized, double-blind, dose-finding study, we evaluated senicapoc's safety and its effect on hemoglobin level and markers of RBC hemolysis in sickle cell anemia patients. The patients were randomized into 3 treatment arms: placebo; low-dose (6 mg/day) senicapoc; and high-dose (10 mg/day) senicapoc. For the primary efficacy end point (change in hemoglobin level from baseline), the mean response to high-dose senicapoc treatment exceeded placebo (6.8 g/L [0.68 g/dL] vs 0.1 g/L [0.01 g/dL], P < .001). Treatment with high-dose senicapoc also produced significant decreases in such secondary end points as percentage of dense RBCs (-2.41 vs -0.08, P < .001); reticulocytes (-4.12 vs -0.46, P < .001); lactate dehydrogenase (-121 U/L vs -15 U/L, P = .002); and indirect bilirubin (-1.18 mg/dL vs 0.12 mg/dL, P < .001). Finally, senicapoc was safe and well tolerated. The increased hemoglobin concentration and concomitant decrease in the total number of reticulocytes and various markers of RBC destruction following senicapoc administration suggests a possible increase in the survival of sickle RBCs. This study is registered at http://clinicaltrials.gov as NCT00040677.
[Show abstract][Hide abstract] ABSTRACT: The thalassemias pose an increasing burden for health-care services in many Asian countries. In order to conserve rare resources, it is essential to determine the reasons for the remarkable phenotypic heterogeneity and natural history of these disorders so that the most cost-effective methods for their control and management can be established. A long-term observational study of patients with different forms of thalassemia in Sri Lanka suggests that in addition to the well-defined primary, secondary and tertiary genetic modifiers, environmental factors, particularly malaria, and variation in the ability to adapt to the profound anaemia which characterizes these conditions, may play a significant role in determining their clinical severity. These findings may have important implications for the control and management of thalassemia in Asian populations.
Full-text · Article · Nov 2004 · Human Molecular Genetics