Sickle cell vaso-occlusion causes activation of iNKT cells that is decreased by the adenosine A2A receptor agonist regadenoson.

Adenosine A2A receptor (A2AR) agonists reduce invariant natural killer T (iNKT) cell activation and decrease inflammation in sickle cell disease (SCD) mice. We conducted a phase 1 trial of the A2AR agonist regadenoson in adults with SCD. The target dose was 1.44 µg/kg/h. iNKT cell activation was evaluated using antibodies targeting the p65 subunit of nuclear factor-κB (phospho-NF-κB p65), interferon-γ (IFN-γ), and A2AR. Regadenoson was administered to 27 adults with SCD. We examined 21 patients at steady state and 6 during painful vaso-occlusive crises (pVOC). iNKT cell activation was also measured in 14 African-American controls. During pVOC, the fraction of iNKT cells demonstrating increased phospho-NF-κB p65 and A2AR expression was significantly higher compared with controls (P < .01) and steady-state patients (P < .05). IFN-γ expression was also significantly higher compared with controls (P = .02). After a 24-hour infusion of regadenoson during pVOC, phospho-NF-κB p65 activation in iNKT cells decreased compared to baseline by a median of 48% (P = .03) to levels similar to controls and steady-state SCD. No toxicities were identified. Infusional regadenoson administered to adults with SCD at 1.44 µg/kg/h during pVOC decreases activation of iNKT cells without toxicity.

National trends in hospitalizations for sickle cell disease in the United States following the FDA approval of hydroxyurea, 1998-2008.

BACKGROUND: Patients with sickle cell disease (SCD) can suffer frequent hospital admissions for painful vasoocclusive crises. Hydroxyurea was approved by the FDA in 1998 to decrease the morbidity of SCD, but nationwide hospitalizations for SCD in the United States since 1998 have not been evaluated. We hypothesized that the availability of hydroxyurea for SCD would be associated with a decrease in hospitalizations for SCD over time. OBJECTIVE: To assess trends in hospitalization and length-of-stay in hospital for SCD in the United States, 1998 through 2008. RESEARCH DESIGN: Retrospective cohort study of SCD-related hospital discharges in the Nationwide Inpatient Sample of US hospital discharges. SUBJECTS: All discharges in the Nationwide Inpatient Sample associated with a principal diagnosis of SCD in blacks, 1998 through 2008. MEASURES: Trends in hospitalization rates and average length-of-stay in hospital for SCD. RESULTS: We found 216 (95% confidence interval, 173.3-258.7) SCD-related hospitalizations per 100,000 US blacks in 1998 and 178.4 (95% confidence interval, 144.2-212.5) in 2008, but no consistent yearly decrease, 1998 through 2008 (P=0.30). Conversely, the length-of-stay in hospital in 1998 was 5.38 days and in 2008 was 5.18 days, an absolute change of 0.2 days and a downward trend that was statistically significant. CONCLUSIONS: Between 1998 and 2008, there was not a steady decrease in hospitalization rates for the population of SCD in the United States. On the contrary, there was a decline in length-of-stay in hospital over this time. Hydroxyurea underuse is well documented. Efforts to increase hydroxyurea use may help to reduce hospitalization rates.

Comparative rates of adverse events with different formulations of intravenous iron.

Oral iron replacement is the standard therapy in iron-deficiency anemia (IDA). However, 59% of patients have gastrointestinal toxicity. With impaired iron uptake from the gastrointestinal tract (in anemia of chronic disease (ACD) or after bariatric surgery), suboptimal responsiveness to exogenous erythropoietin (in chronic renal failure), in patients with cancer receiving chemotherapy, or when oral iron is poorly tolerated, IV iron therapy is the preferred mode of repletion. Although effective in increasing hemoglobin, the relative safety of the available IV iron preparations is not well documented. We examined the comparative safety of IV iron formulations used at hospitals associated with our institution. Among 619 unique patients who received IV iron over a 2-year period, we found 32 adverse events (AEs), ranging from urticaria to chest pain. There were no serious AEs or anaphylactic-type reactions. In a multivariate model, there was no difference in AE rates between low-molecular-weight iron dextran (LMWD) and ferric gluconate; however, iron sucrose had significantly higher odds ratio of AEs (OR = 5.7; 95% CI = 1.6­21.3). Our data suggest that AE rates with IV iron are acceptable. More widespread use of LMWD, in particular, which can be given safely as a total dose infusion (TDI), should be considered.

Nitric oxide for inhalation in the acute treatment of sickle cell pain crisis: a randomized controlled trial.

CONTEXT: Inhaled nitric oxide has shown evidence of efficacy in mouse models of sickle cell disease (SCD), case series of patients with acute chest syndrome, and 2 small placebo-controlled trials for treatment of vaso-occlusive pain crisis (VOC). OBJECTIVE: To determine whether inhaled nitric oxide gas reduces the duration of painful crisis in patients with SCD who present to the emergency department or hospital for care. DESIGN, SETTING, AND PARTICIPANTS: Prospective, multicenter, double-blind, randomized, placebo-controlled clinical trial for up to 72 hours of inhaled nitric oxide gas vs inhaled nitrogen placebo in 150 participants presenting with VOC of SCD at 11 centers between October 5, 2004, and December 22, 2008. Intervention Inhaled nitric oxide gas vs inhaled nitrogen placebo. MAIN OUTCOME MEASURES: The primary end point was the time to resolution of painful crisis, defined by (1) freedom from parenteral opioid use for 5 hours; (2) pain relief as assessed by visual analog pain scale scores of 6 cm or lower (on 0-10 scale); (3) ability to walk; and (4) patient's and family's decision, with physician consensus, that the remaining pain could be managed at home. RESULTS: There was no significant change in the primary end point between the nitric oxide and placebo groups, with a median time to resolution of crisis of 73.0 hours (95% confidence interval [CI], 46.0-91.0) and 65.5 hours (95% CI, 48.1-84.0), respectively (P = .87). There were no significant differences in secondary outcome measures, including length of hospitalization, visual analog pain scale scores, cumulative opioid usage, and rate of acute chest syndrome. Inhaled nitric oxide was well tolerated, with no increase in serious adverse events. Increases in venous methemoglobin concentration confirmed adherence and randomization but did not exceed 5% in any study participant. Significant increases in plasma nitrate occurred in the treatment group, but there were no observed increases in plasma or whole blood nitrite. CONCLUSION: Among patients with SCD hospitalized with VOC, the use of inhaled nitric oxide compared with placebo did not improve time to crisis resolution. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00094887.

Iron Supplementation, Response in Iron-Deficiency Anemia: Analysis of Five Trials.

BACKGROUND: Oral iron-replacement therapy is the mainstay of treatment for iron-deficiency anemia, but it is often poorly tolerated or ineffective. Hemoglobin response at day 14 of oral iron may be useful in assessing whether and when to transition patients from oral to intravenous (IV) iron. METHODS: Pooled data from 5 randomized trials were analyzed to compare oral and IV iron-replacement therapy for iron-deficiency anemia. Treatment criteria and assignment to oral versus IV iron were defined per protocol; this analysis included only subjects receiving oral iron. Responders were subjects with ≥1.0-g/dL increases in hemoglobin at day 14, and nonresponders were those with smaller increases. Demographic and clinical characteristics were evaluated for association with hemoglobin response at multiple timepoints. RESULTS: Most subjects (72.8%) were classified as responders. The proportion of subjects with hemoglobin increases ≥1.0, ≥2.0, and ≥3.0 g/dL was greatest among those with postpartum anemia, intermediate among those with heavy uterine bleeding or gastrointestinal-related causes of anemia, and lowest among those with other causes; this proportion was also significantly greater among responders than nonresponders. A ≥1.0-g/dL increase in hemoglobin on day 14 most accurately predicted satisfactory overall hemoglobin response to oral iron on day 42/56 (sensitivity 90.1%; specificity 79.3%; positive and negative predictive values of 92.9% and 72.7%, respectively). Iron-replacement therapy improved quality of life and reduced fatigue. CONCLUSION: Hemoglobin responses <1.0 g/dL at day 14 of oral iron identify subjects with iron-deficiency anemia who should be transitioned to IV iron supplementation.

Novel approaches to the treatment of sickle cell disease: the potential of histone deacetylase inhibitors.

Sickle cell disease (SCD) is a severe genetic disorder of hemoglobin causing vaso-occlusion. Patients suffer severe anemia, strokes, renal failure, pulmonary compromise and shortened life expectancy. Over 90,000 people in the USA have SCD, and the options for therapy are limited and only partially effective. With the available therapies - hydroxyurea, blood transfusion, hydration and pain medicines - patients continue to suffer the long-term complications of the disease. This review focuses on the pathogenesis of SCD and the role of fetal hemoglobin in disrupting the polymerization of sickle hemoglobin. The authors review the compounds that induce fetal hemoglobin: hydroxyurea, which is currently US FDA approved, and the histone deacetylase inhibitors and discuss their role in the treatment of SCD and other ß-hemoglobinopathies.

Anemia in pregnancy.

Anemia in pregnancy is a global health problem affecting nearly half of all pregnant women worldwide. High fetal demands for iron render iron deficiency the most common cause of anemia of pregnancy, with other micronutrient deficiencies contributing less frequently. In certain geographical populations, human pathogens such as hookworm, malarial parasite and human immunodeficiency virus are important factors in anemia of pregnancy. The hemoglobinopathies, sickle cell disease and thalassemia, represent diverse causes of anemia of pregnancy, requiring specialized care. Aplastic anemia is a rare, morbid cause of anemia of pregnancy and is managed with transfusions until the completion of pregnancy.