Interleukin-1β and interleukin-6 gene polymorphisms are associated with manifestations of sickle cell anemia

Sickle cell anemia (SCA), a disorder characterized by both acute and chronic inflammation, exhibits substantial phenotypic variability. Interleukin-1 beta (IL-1β) and IL-6 are important in acute and chronic diseases, and their single nucleotide polymorphisms (SNPs) have been considered as predictors of prognosis in several inflammatory conditions. This study aims at exploring possible association of IL-1β and IL-6 SNPs as potential genetic modifiers and or predictors of SCA clinical and laboratory phenotypes. This cross-sectional study involved 107 SCA patients and 110 age, sex and ethnicity-matched healthy individuals. The SNPs were identified by PCR-RFLP for IL-1β (-511C>T and +3954C>T) and IL-6 (-597G>A and -174G>C) genes. Associations between these SNPs and the clinical and laboratory profiles of patients with SCA were then determined. Allelic and genotypic frequencies of IL-1β and IL-6 SNPs between patients with SCA and controls were similar and followed HWE. IL-1β +3954C>T SNP was associated with increased risk of osteonecrosis, elevated pulmonary arterial pressure and lower absolute reticulocyte count, while IL-6 -597G>A was associated with higher likelihood of retinopathy and leg ulcer. These data indicate that IL-1β and IL-6 gene SNPs are associated with SCA complications among Brazilian patients and may act as genetic predictors of SCA clinical heterogeneity.

Exercise-Induced Abnormal Increase of Systolic Pulmonary Artery Pressure in Adult Patients With Sickle Cell Anemia: An Exercise Stress Echocardiography Study

BACKGROUND

Pulmonary hypertension (PH) at rest is a risk factor for death in patients with sickle cell anemia (SCA). Exercise echocardiography (EE) can detect latent PH. We sought to investigate the occurrence of exercise-induced abnormal response of systolic pulmonary artery pressure (SPAP) in adult patients with SCA and normal SPAP at rest, and to identify the independent predictors of this abnormal response.

METHODS AND RESULTS

Forty-four adult patients with SCA and normal SPAP at rest (tricuspid regurgitant jet flow velocity [TRV] <2.5 m/sec) were studied and divided into 2 groups: exhibiting normal SPAP after treadmill EE (TRV ≤ 2.7 m/sec) (G1), and exhibiting abnormal exercise-induced increase of SPAP (TRV > 2.7 m/sec) (G2). TRV cutoff points at rest and during EE were based on data from healthy-matched control subjects. Abnormal response of SPAP with exercise occurred in 57% of the sample (G2), with mean TRV level of 3.39 ± 0.41 m/sec (range 2.8-4.5 m/sec), significantly higher than those of G1 (2.29 ± 0.25 m/sec, range 2.0-2.7 m/sec; P < 0.001). Multivariate analysis identified TRV value in resting conditions ≥2.25 m/sec (P < 0.05), left atrial volume index ≥41 mL/m² (P < 0.05), and a E/e'-waves ratio ≥6.3 (P < 0.05) as independent predictors of exercise-induced increase of SPAP.

CONCLUSION

We concluded that adult patients with SCA and normal SPAP at rest may exhibit abnormal exercise-induced increase in SPAP, which was independently related to resting TRV levels, and indices of diastolic impairment and left ventricular filling pressure.

Priapism is associated with sleep hypoxemia in sickle cell disease

PURPOSE

We assessed penile rigidity during sleep and the relationship of sleep abnormalities with priapism in adults with sickle cell disease.

MATERIALS AND METHODS

This was a case-control study of 18 patients with sickle cell disease and a history of priapism during the previous year, and 16 controls with sickle cell disease. Participants underwent overnight polysomnography and RigiScan® Plus recording to detect penile rigidity oscillations.

RESULTS

The priapism group (cases) showed a higher apnea-hypopnea index and oxyhemoglobin desaturation parameters than controls. A lower positive correlation between the apnea-hypopnea index and oxyhemoglobin desaturation time was observed in cases than in controls (Spearman coefficient ρ = 0.49, p = 0.05 vs ρ = 0.76, p <0.01), suggesting that desaturation events occurred independently of apnea. Two controls and 14 cases had a total sleep time that was greater than 10% with oxyhemoglobin saturation less than 90% but without CO(2) retention. Penile rigidity events were observed during rapid eye movement sleep and during stage 2 of nonrapid eye movement sleep, particularly in cases. The duration of penile rigidity events concomitant to respiratory events was higher in cases than in controls. Regression analysis revealed that the periodic limb movement and desaturation indexes were associated with priapism after adjusting for rapid eye movement sleep and lung involvement. Finally, oxyhemoglobin saturation less than 90% was associated with priapism after adjusting for lung involvement, hyperhemolysis and the apnea-hypopnea index.

CONCLUSIONS

Oxyhemoglobin desaturation during sleep was associated with priapism history. It may underlie the distribution pattern of penile rigidity events during sleep in these patients.

Bone marrow and peripheral white blood cells number is affected by sleep deprivation in a murine experimental model

Sleep deficit and related disorders are becoming increasingly prevalent in modern life and an extensive literature has documented that acute or chronic sleep deprivation can lead to several physiological consequences. Here, we evaluated the effects of sleep deprivation on hematopoietic composition of either bone marrow or peripheral blood. Mice were subjected to paradoxical sleep deprivation (PSD) for 72 h by modified multiple platform method, with or without an additional sleep recovery (SR) period of 10 days. PSD decreased total cellularity of the bone marrow and peripheral blood concomitantly. Subsequent analysis of cell composition showed that absolute number of hematopoietic stem/progenitor cells and colony-forming units was decreased. Moreover, the absolute number of granulocytes and monocytes in bone marrow was reduced in PSD group. These alterations were paralleled by an accumulation of neutrophils and monocytes in peripheral blood. PSD also induced lymphopenia in the circulation. To the best of our knowledge, this is the first study that demonstrates the importance of sleep on the hematopoietic microenvironment and provides new insights into the relationship between sleep and the immune system.

Molecular analysis of β-thalassemia patients: first identification of mutations HBB:c.93-2A>G and HBB:c.114G>A in Brazil

The various clinical phenotypes in β-thalassemias have stimulated the study of genetic factors that could modify the manifestations of these diseases. We examined 21 patients with β-thalassemia (β-thal) in order to identify some genetic modifying factors: β-thalassemia mutations, HBG2:g.-158C>T polymorphism, α-globin gene deletions and (AT)xNz(AT)y motif within the hypersensitive site 2-locus control region (HS2-LCR). In the 42 alleles analyzed, the most frequent mutations observed were HBB:c.92+6T>C (30.9%), HBB:c.118C>T (16.7%), HBB:c.93-21G>A (11.9%) and HBB:c.92+1G>A (4.8%); this finding is in accordance with previous data of the Brazilian population. The other genetic factors analyzed showed no relation with the severity of the disease. For the first time in Brazil, we report HBB:c.93-2A>G and HBB:c.114G>A mutations on the β-globin gene, both in a heterozygous state. This is also the first study to analyze the HS2-LCR in β-thalassemic individuals in the Brazilian population.

Absence of association between TNF-α polymorphism and cerebral large-vessel abnormalities in adults with sickle cell anemia

Stroke is a serious complication of sickle cell anemia (SCA) affecting children and adults. Recent reports suggested that tumor necrosis factor-α (TNF-α) (-308) polymorphism is an important risk factor for stroke in children with SCA. The role of TNF-α polymorphism in the frequency of brain magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) abnormalities in adults with SCA is still uncertain. Our objective was to evaluate the frequency of TNF-α polymorphism in adults with SCA and to correlate it to brain MRI and MRA findings. TNF-α (-308) polymorphism was determined in 49 adults with SCA. All subjects were evaluated with brain MRI/MRA to establish the presence of intracranial abnormalities. Thirty-three (67.3%) had abnormal brain MRA scans, 8 (16.3%) had intracranial stenosis and 29 (59.2%) showed arterial tortuosity. Forty-one (83.7%) had the GG genotype and 8 had the GA genotype. There was no correlation between homozygosity for G allele and MRA or MRI abnormalities. Although TNF-α (-308) polymorphism is a potential predictor of the genetic risk for stroke in children, we found no association between the polymorphism and large vessel abnormalities in adults with SCA.

Brain magnetic resonance imaging abnormalities in adult patients with sickle cell disease: correlation with transcranial Doppler findings

BACKGROUND AND PURPOSE

Brain imaging abnormalities were reported in up to 44% of children with sickle cell disease (SCD). The prevalence of neuroimaging abnormalities in adult patients with SCD and their relationship to transcranial Doppler is still unclear. Our objectives were to study the frequency of MRI and MR angiography abnormalities in adults with SCD and to define what transcranial Doppler velocities are associated with intracranial stenoses detected by MR angiography.

METHODS

We examined all adult patients (>16 years) with SCD followed in the hematology outpatient clinic at our university hospital with MRI, MR angiography, and transcranial Doppler.

RESULTS

We evaluated 50 patients. The overall prevalence of MRI abnormalities was 60%. Abnormal MRI findings were more frequent when vessel tortuosity or stenoses were present on MR angiography (P<0.01). Patients with intracranial stenoses had significantly higher time-averaged maximum mean velocities (P=0.01). A time-averaged maximum mean velocity of 123.5 cm/s allowed the diagnosis of middle cerebral artery or internal carotid artery intracranial stenosis with sensitivity of 100% and specificity of 73% with an area under the receiver operator characteristic curve of 0.91 (CI, 0.79 to 1.00).

CONCLUSIONS

The frequency of brain imaging abnormalities detected by MRI/MR angiography in adults with SCD was higher than that described for children. Transcranial Doppler velocities in adult patients with intracranial stenoses were lower than those described for the pediatric population with SCD.

Multiple primary choledocholithiasis in sickle cell disease

Choledocholithiasis can be caused by either primary or secondary bile duct stones. Although patients with sickle cell disease (SCD) are at high risk of development of pigmented gallstones due to chronic hemolysis, primary choledocholithiasis in SCD is very uncommon. The delay in the diagnosis of biliary tract pathology can occur in patients who had a prior cholecystectomy. There is a possible relationship between prior cholecystectomy and the subsequent occurrence of primary common bile duct stones, due to the higher probability of infection of the biliary system. Here, we report an unusual and severe case of multiple primary choledocholithiasis, associated with pancreatitis, in a patient with SCD, fourteen years after cholecystectomy.

Transcranial Doppler ultrasonography in adults with sickle cell disease

BACKGROUND

Transcranial Doppler (TCD) is used to select children with sickle cell disease (SCD) for primary stroke prevention using regular blood transfusion. Whether it can also identify high stroke risk in adults with SCD is not known.

METHODS

The authors examined 112 adult patients from two convenience population samples with SCD and 53 healthy control subjects to compare velocities in adults to those reported in children with SCD and to evaluate the influence of age and hematocrit on TCD.

RESULTS

Adults with SCD had a higher mean time-averaged maximum mean velocity (110.9 +/- 25.7 cm/s) compared with healthy controls (71.1 +/- 12.0 cm/s), and the difference is approximately proportional to their anemia. No cases with velocities >/=200 cm/s (the threshold used in children for prophylactic treatment) were found in this sample.

CONCLUSIONS

Transcranial Doppler velocities in adults with sickle cell disease (SCD) are lower than those in children with SCD. Velocity criteria used in children cannot be used to stratify risk of stroke in adults.

Migraine-mimicking headache and sickle cell disease: a transcranial Doppler study

Headache occurs in sickle cell disease (SCD), but its characteristics and frequency have not previously been studied. Our aim was to study patterns of headache in adults with SCD and to correlate its presence with blood flow velocities measured by transcranial Doppler (TCD) and with brain magnetic resonance imaging (MRI) abnormalities. We studied 56 adults with SCD. Twenty-eight patients (50%) had severe and frequent headaches. In 20 patients (35.7%) the headache met the International Headache Society criteria for migraine without aura. Patients with frequent and severe headache presented TCD velocities significantly higher than those without headache, or with milder headache. No correlation was found between headache and abnormalities in brain MRI. A migraine-mimicking headache occurs in SCD but we should not understand it as a primary headache because the blood flow abnormalities secondary to SCD detected by TCD seem to play an important role in these patients.

XmnI polymorphism is associated with fetal hemoglobin levels in hypoplastic syndromes

CONTEXT AND OBJECTIVE

Acquired fetal hemoglobin (HbF) elevation has been implicated as a prognostic factor in dyserythropoietic disorders. Our objectives were to examine acquired HbF increases in aplastic anemia (AA) and paroxysmal nocturnal hemoglobinuria (PNH) patients, and to evaluate whether there is an association between the presence of XmnI and 5' hypersensitive site locus control region (LCR-HS2) polymorphisms and the HbF levels.

DESIGN AND SETTING

Cross-sectional study at the Hematology and Blood Transfusion Service of Universidade Federal de São Paulo - Escola Paulista de Medicina.

METHODS

We studied a group of 37 patients with AA and/or PNH. Polymerase chain reaction (PCR) and enzymatic digestion were utilized to analyze XmnI polymorphisms; and PCR, cloning and automated sequencing for the HS2 polymorphisms.

RESULTS

The mean HbF level was 2.32%, but there was no significant difference in HbF level between the AA and PNH groups (p = 0.46). HbF levels of less than 1.0% showed a significant correlation with absence of the XmnI (+) polymorphism (p = 0.02). The presence of the XmnI allele was greater in the AA group (p = 0.007).

CONCLUSIONS

XmnI polymorphism absence reduction is associated with acquired HbF elevation. Further studies are required to confirm these observations and make treatment, prognosis and survival comparisons.

Transcranial Doppler in Adult Patients with Sickle Cell Disease

BACKGROUND

Transcranial Doppler (TCD) is the key test in determining the need for prophylactic blood transfusion to prevent stroke in children with sickle cell disease (SCD). The role of TCD in assessing stroke risk in adults with SCD as well as the pattern of TCD velocities in these patients are still undetermined.

METHODS

The authors compared TCD velocities in SCD adults (n=56) with those of healthy controls (n=56).

RESULTS

Velocities in SCD adults were lower than those found in children and higher than in controls and negatively correlated to hematocrit in both groups.

CONCLUSION

The pattern of TCD velocities in adults with SCD is different from that described in children. Age-specific TCD criteria may assist the detection of stroke risk in these patients.