Loss of miR-144/451 alleviates ß-thalassemia by stimulating ULK1-mediated autophagy of free α-globin.

Most cells can eliminate unstable or misfolded proteins through quality control mechanisms. In the inherited red blood cell disorder ß-thalassemia, mutations in the ß-globin gene (HBB) lead to a reduction in the corresponding protein and the accumulation of cytotoxic free α-globin, which causes maturation arrest and apoptosis of erythroid precursors and reductions in the lifespan of circulating red blood cells. We showed previously that excess α-globin is eliminated by Unc-51-like autophagy activating kinase 1 (ULK1)-dependent autophagy and that stimulating this pathway by systemic mammalian target of rapamycin complex 1 (mTORC1) inhibition alleviates ß-thalassemia pathologies. We show here that disrupting the bicistronic microRNA gene miR-144/451 alleviates ß-thalassemia by reducing mTORC1 activity and stimulating ULK1-mediated autophagy of free α-globin through 2 mechanisms. Loss of miR-451 upregulated its target messenger RNA, Cab39, which encodes a cofactor for LKB1, a serine-threonine kinase that phosphorylates and activates the central metabolic sensor adenosine monophosphate-activated protein kinase (AMPK). The resultant enhancement of LKB1 activity stimulated AMPK and its downstream effects, including repression of mTORC1 and direct activation of ULK1. In addition, loss of miR-144/451 inhibited the expression of erythroblast transferrin receptor 1, causing intracellular iron restriction, which has been shown to inhibit mTORC1, reduce free α-globin precipitates, and improve hematological indices in ß-thalassemia. The beneficial effects of miR-144/451 loss in ß-thalassemia were inhibited by the disruption of Cab39 or Ulk1 genes. Together, our findings link the severity of ß-thalassemia to a highly expressed erythroid microRNA locus and a fundamental, metabolically regulated protein quality control pathway that is amenable to therapeutic manipulation.

Gene Therapy and Gene Editing for ß-Thalassemia.

After many years of intensive research, emerging data from clinical trials indicate that gene therapy for transfusion-dependent ß-thalassemia is now possible. Strategies for therapeutic manipulation of patient hematopoietic stem cells include lentiviral transduction of a functional erythroid-expressed ß-globin gene and genome editing to activate fetal hemoglobin production in patient red blood cells. Gene therapy for ß-thalassemia and other blood disorders will invariably improve as experience accumulates over time. The best overall approaches are not known and perhaps not yet established. Gene therapy comes at a high cost, and collaboration between multiple stakeholders is required to ensure that these new medicines are administered equitably.

Clinical characteristics and outcomes of children with newly diagnosed acute myeloid leukemia and hyperleukocytosis managed with different cytoreductive methods.

BACKGROUND: Hyperleukocytosis in patients with acute myeloid leukemia (AML) has been associated with worse outcomes. For cytoreduction, leukapheresis has been used but its clinical utility is unknown, and low-dose cytarabine (LD-cytarabine) is used as an alternative method. METHODS: Children with newly diagnosed AML treated between 1997 and 2017 in institutional protocols were studied. Hyperleukocytosis was defined as a leukocyte count of ≥100 × 109 /L at diagnosis. Clinical characteristics, early complications, survival data, and effects of cytoreductive methods were reviewed. Among 324 children with newly diagnosed AML, 49 (15.1%) presented with hyperleukocytosis. Initial management of hyperleukocytosis included leukapheresis or exchange transfusion (n = 16, considered as one group), LD-cytarabine (n = 18), hydroxyurea (n = 1), and no leukoreduction (n = 14). RESULTS: Compared with patients who received leukapheresis, the percentage decrease in leukocyte counts following intervention was greater among those who received LD-cytarabine (48% vs. 75%; p = .02), with longer median time from diagnosis to initiation of protocol therapy (28.1 vs. 95.2 hours; p < .001). The incidence of infection was higher in patients (38%) who had leukapheresis than those who receive LD-cytarabine (0%) or leukoreduction with protocol therapy (14%) (p = .008). No differences were noted in the outcomes among the intervention groups. Although patients with hyperleukocytosis had higher incidences of pulmonary and metabolic complications than did those without, no early deaths occurred, and the complete remission, event-free survival, overall survival rates, and outcomes of both groups were similar. CONCLUSION: LD-cytarabine treatment appears to be a safe and effective means of cytoreduction for children with AML and hyperleukocytosis.

Activation of γ-globin expression by hypoxia-inducible factor 1α.

Around birth, globin expression in human red blood cells (RBCs) shifts from γ-globin to ß-globin, which results in fetal haemoglobin (HbF, α2γ2) being gradually replaced by adult haemoglobin (HbA, α2ß2)1. This process has motivated the development of innovative approaches to treat sickle cell disease and ß-thalassaemia by increasing HbF levels in postnatal RBCs2. Here we provide therapeutically relevant insights into globin gene switching obtained through a CRISPR-Cas9 screen for ubiquitin-proteasome components that regulate HbF expression. In RBC precursors, depletion of the von Hippel-Lindau (VHL) E3 ubiquitin ligase stabilized its ubiquitination target, hypoxia-inducible factor 1α (HIF1α)3,4, to induce γ-globin gene transcription. Mechanistically, HIF1α-HIF1ß heterodimers bound cognate DNA elements in BGLT3, a long noncoding RNA gene located 2.7 kb downstream of the tandem γ-globin genes HBG1 and HBG2. This was followed by the recruitment of transcriptional activators, chromatin opening and increased long-range interactions between the γ-globin genes and their upstream enhancer. Similar induction of HbF occurred with hypoxia or with inhibition of prolyl hydroxylase domain enzymes that target HIF1α for ubiquitination by the VHL E3 ubiquitin ligase. Our findings link globin gene regulation with canonical hypoxia adaptation, provide a mechanism for HbF induction during stress erythropoiesis and suggest a new therapeutic approach for ß-haemoglobinopathies.

Effective therapies for sickle cell disease: are we there yet?

Sickle cell disease (SCD) is a common genetic blood disorder associated with acute and chronic pain, progressive multiorgan damage, and early mortality. Recent advances in technologies to manipulate the human genome, a century of research and the development of techniques enabling the isolation, efficient genetic modification, and reimplantation of autologous patient hematopoietic stem cells (HSCs), mean that curing most patients with SCD could soon be a reality in wealthy countries. In parallel, ongoing research is pursuing more facile treatments, such as in-vivo-delivered genetic therapies and new drugs that can eventually be administered in low- and middle-income countries where most SCD patients reside.

Phase I Dose-Finding, Safety, and Tolerability Trial of Romiplostim to Improve Platelet Recovery After UCB Transplantation.

Platelet recovery is delayed after umbilical cord blood transplant (UCBT). Romiplostim is a thrombopoietin receptor agonist that has the potential to improve platelet engraftment after UCBT. The purpose of this study was to determine the safety profile and maximum tolerated dose (MTD) of romiplostim and to investigate whether romiplostim accelerates platelet recovery post-UCBT. It was a single-center, dose-finding, safety and tolerability phase I trial of weekly romiplostim in 20 adult patients who failed to achieve an un-transfused platelet count of 20 × 109/L by day +28 post-UCBT. Romiplostim was administered at the assigned dose as 6 weekly injections beginning by day +42 post-UCBT. Four dose levels (4, 6, 8, and 10 µg/kg per dose) were evaluated. The MTD of romiplostim was determined by the continual reassessment method, with a goal to identify a dose level with desired toxicity rate of ≤20%. Median age of the patients was 59.5 years, and 60% were female. Eleven patients received nonmyeloablative (NMA) double UCBT, seven patients received myeloablative single UCBT, and two patients received NMA single UCBT. Two patients received 4 µg/kg per dose, two received 6 µg/kg per dose, four received 8 µg/kg per dose, and the remaining 12 received 10 µg/kg per dose. Only five patients completed the full six doses of treatment. Of the 15 patients who received fewer than six doses, 12 were due to a platelet count of >100 × 109/L, two were due to platelet count of >400 × 109/L, and one was due to right upper extremity edema without thrombosis. All romiplostim-treated patients achieved platelet engraftment to 20 × 109/L at a median of 45 days post-UCBT compared to 90% of controls at a median of 45 days (P = .08). Similarly, 90% of romiplostim-treated patients achieved platelet engraftment to 50 × 109/L at a median of 48 days compared to 75% of controls at a median of 52 days (P = .09). All dose levels were effective with low toxicity; therefore, the MTD of romiplostim was 10 µg/kg per dose, and romiplostim is a safe and potentially effective therapy to counter delayed platelet recovery post-UCBT.

Hereditary elliptocytosis-associated alpha-spectrin mutation p.L155dup as a modifier of sickle cell disease severity.

The broad phenotypic variability among individuals with sickle cell disease (SCD) suggests the presence of modifying factors. We identified two unrelated SCD patients with unusually severe clinical and laboratory phenotype that were found to carry the hereditary elliptocytosis-associated alpha-spectrin mutation c.460_462dupTTG (p.L155dup), a mutation enriched due to positive selective pressure of malaria, similar to the SCD globin mutations. A high index of suspicion for additional hematologic abnormalities may be indicated for challenging patients with SCD. These cases highlight the validity of specialized testing such as ektacytometry and next-generation sequencing for patients and family members to assess genotype/phenotype correlations.

Predictors of Excess Patient Radiation Exposure During Chronic Total Occlusion Coronary Intervention: Insights From a Contemporary Multicentre Registry.

BACKGROUND: High patient radiation dose during chronic total occlusion (CTO) percutaneous coronary intervention (PCI) might lead to procedural failure and radiation skin injury. METHODS: We examined the association between several clinical and angiographic variables on patient air kerma (AK) radiation dose among 748 consecutive CTO PCIs performed at 9 experienced US centres between May 2012 and May 2015. RESULTS: The mean age was 65 ± 10 years, 87% of patients were men, and 35% had previous coronary artery bypass graft surgery (CABG). Technical and procedural success was 92% and 90%, respectively. The median patient AK dose was 3.40 (interquartile range, 2.00-5.40) Gy and 34% of the patients received > 4.8 Gy (high radiation exposure). In univariable analysis male sex (P = 0.016), high body mass index (P < 0.001), history of hyperlipidemia (P = 0.023), previous CABG (P < 0.001), moderate or severe calcification (P < 0.001), tortuosity (P < 0.001), proximal cap ambiguity (P = 0.001), distal cap at a bifurcation (P = 0.006), longer CTO occlusion length (P < 0.001), blunt/no blunt stump (P < 0.001), and centre (P < 0.001) were associated with higher patient AK dose. In multivariable analysis high body mass index (P < 0.001), previous CABG (P = 0.005), moderate or severe calcification (P = 0.005), longer CTO occlusion length (P < 0.001), and centre (P < 0.001) were independently associated with higher patient AK dose. CONCLUSIONS: Approximately 1 in 3 patients who undergo CTO PCI receive high AK radiation dose (> 4.8 Gy). Several baseline clinical and angiographic characteristics can help predict the likelihood of high radiation dose and assist with intensifying efforts to reduce radiation exposure for the patient and the operator.

RGL2 Deficiency Impairs Human Erythropoiesis By Altering Terminal Erythroid Differentiation and Apoptosis.

DISCLOSURES: No relevant conflicts of interest to declare.

Near-Infrared Spectroscopy Analysis of Coronary Chronic Total Occlusions.

OBJECTIVE: To examine the presence and localization of lipid-core plaque (LCP) in coronary vessels with chronic total occlusions (CTOs) using near-infrared spectroscopy (NIRS). METHODS: NIRS imaging was performed after guidewire crossing of the occlusion in 15 patients with CTOs. LCP was defined as ≥2 adjacent 2 mm yellow blocks on the block chemogram. We also measured the maximum lipid-core burden index (LCBI) in a 4 mm length of artery (maxLCBI4mm). Large LCP was defined as maxLCBI4mm ≥500. RESULTS: Median patient age was 64 years (interquartile range [IQR], 61-67 years) and all patients were men with high prevalence of diabetes mellitus (64%) and prior coronary artery bypass graft surgery (27%). The CTO target vessel was the right coronary artery (46%), left anterior descending artery (27%), or circumflex artery (27%). Median occlusion length was 35 mm (IQR, 30-50 mm). LCP was present in 11 of 15 CTO vessels (73%) and a large LCP in 4 of 15 CTO vessels (27%). LCP was located at the proximal cap in 6 CTOs (55%), the CTO body in 6 CTOs (55%), and the distal cap in 2 CTOs (18%). The median overall LCBI and maxLCBI4mm were 145 (IQR, 79-243) and 415 (IQR, 267-505), respectively. All patients underwent successful stenting without any complications. The 12-month incidence of in-stent restenosis and target-lesion revascularization was 25%, and all patients who developed restenosis had an LCP at baseline. CONCLUSIONS: LCPs are commonly encountered in coronary CTO vessels, suggesting an active intraplaque atherosclerotic process. The impact of LCP on postintervention outcomes requires further study.

Impact of Chronic Total Occlusion Revascularization Attempts on Subsequent Clinical Outcomes.

OBJECTIVES: We examined a contemporary, unselected cohort of patients with coronary chronic total occlusions (CTOs) to determine the impact of CTO revascularization on long-term outcomes. METHODS: We retrospectively assessed the impact of CTO revascularization on clinical outcomes of consecutive patients found to have a CTO during coronary angiography performed at our institution during 2011 and 2012. The primary endpoint was the incidence of a major adverse cardiac event (MACE, defined as a composite of death, myocardial infarction, stroke, and target-vessel revascularization [TVR]). Survival analysis was performed in the overall and propensity-matched retrospective cohorts of patients stratified by prior coronary artery bypass graft (CABG) surgery. Propensity-adjusted hazard ratio (HR) and 95% confidence interval (95% CI) were calculated with Cox proportional hazards analysis. All analyses were by intention to treat. RESULTS: Of 624 patients (319 without prior CABG and 305 with prior CABG) included in the present analysis, CTO revascularization (surgical or percutaneous) was attempted in 60% and 16% of patients without and with prior CABG, respectively. During a median follow-up of 26 months (range, 18-40 months), the incidence of MACE was 20.6%. CTO revascularization (achieved or attempted) was associated with lower incidence of MACE among patients without prior CABG (propensity-adjusted HR, 0.51; 95% CI, 0.27-0.94; P=.03), but not among prior CABG patients (propensity-adjusted HR, 1.38; 95% CI, 0.64-2.96; P=.41). CONCLUSION: In a large, unselected patient population with coronary CTOs, a CTO revascularization attempt was associated with lower incidence of subsequent MACE among patients without prior CABG, but not among prior CABG patients.

Accuracy of remote chest X-ray interpretation using Google Glass technology.

OBJECTIVES: We sought to explore the accuracy of remote chest X-ray reading using hands-free, wearable technology (Google Glass, Google, Mountain View, California). METHODS: We compared interpretation of twelve chest X-rays with 23 major cardiopulmonary findings by faculty and fellows from cardiology, radiology, and pulmonary-critical care via: (1) viewing the chest X-ray image on the Google Glass screen; (2) viewing a photograph of the chest X-ray taken using Google Glass and interpreted on a mobile device; (3) viewing the original chest X-ray on a desktop computer screen. One point was given for identification of each correct finding and a subjective rating of user experience was recorded. RESULTS: Fifteen physicians (5 faculty and 10 fellows) participated. The average chest X-ray reading score (maximum 23 points) as viewed through the Google Glass, Google Glass photograph on a mobile device, and the original X-ray viewed on a desktop computer was 14.1±2.2, 18.5±1.5 and 21.3±1.7, respectively (p<0.0001 between Google Glass and mobile device, p<0.0001 between Google Glass and desktop computer and p=0.0004 between mobile device and desktop computer). Of 15 physicians, 11 (73.3%) felt confident in detecting findings using the photograph taken by Google Glass as viewed on a mobile device. CONCLUSION: Remote chest X-ray interpretation using hands-free, wearable technology (Google Glass) is less accurate than interpretation using a desktop computer or a mobile device, suggesting that further technical improvements are needed before widespread application of this novel technology.

Contrast Utilization During Chronic Total Occlusion Percutaneous Coronary Intervention: Insights From a Contemporary Multicenter Registry.

BACKGROUND: Administration of a large amount of contrast volume during chronic total occlusion (CTO) percutaneous coronary intervention (PCI) may lead to contrast-induced nephropathy. METHODS: We examined the association of clinical, angiographic and procedural variables with contrast volume administered during 1330 CTO-PCI procedures performed at 12 experienced United States centers. RESULTS: Technical and procedural success was 90% and 88%, respectively, and mean contrast volume was 289 ± 138 mL. Approximately 33% of patients received >320 mL of contrast (high contrast utilization group). On univariable analysis, male gender (P=.01), smoking (P=.01), prior coronary artery bypass graft surgery (P=.04), moderate or severe calcification (P=.01), moderate or severe tortuosity (P=.04), proximal cap ambiguity (P=.01), distal cap at a bifurcation (P<.001), side branch at the proximal cap (P<.001), blunt/no stump (P=.01), occlusion length (P<.001), higher J-CTO score (P=.02), use of antegrade dissection and reentry or retrograde approach (P<.001), ad hoc CTO-PCI (P=.04), dual arterial access (P<.001), and 8 Fr guide catheters (P<.001) were associated with higher contrast volume; conversely, diabetes mellitus (P=.01) and in-stent restenosis (P=.01) were associated with lower contrast volume. On multivariable analysis, moderate/severe calcification (P=.04), distal cap at a bifurcation (P<.001), ad hoc CTO-PCI (P<.001), dual arterial access (P=.01), 8 Fr guide catheters (P=.02), and use of antegrade dissection/reentry or the retrograde approach (P<.001) were independently associated with higher contrast use, whereas diabetes (P=.02), larger target vessel diameter (P=.03), and presence of "interventional" collaterals (P<.001) were associated with lower contrast utilization. CONCLUSIONS: Several baseline clinical, angiographic, and procedural characteristics are associated with higher contrast volume administration during CTO-PCI.

Prospective Evaluation of the Impact of Side-Holes and Guide-Catheter Disengagement From the Coronary Ostium on Fractional Flow Reserve Measurements.

BACKGROUND: We prospectively examined the impact of side-holes and guide-catheter disengagement on fractional flow reserve (FFR) measurements. METHODS: Twenty-five patients undergoing clinically indicated FFR measurement for intermediate coronary artery stenosis were enrolled. Four FFR measurements were made in random order during intravenous adenosine infusion with: (a) an engaged side-hole guide catheter; (b) a disengaged side-hole guide catheter; (c) an engaged non-side-hole guide catheter; and (d) disengaged non-side-hole guide catheter. RESULTS: Mean patient age was 65 ± 9 years and 100% were men. The mean distal poststenotic pressure/proximal aortic pressure (Pd/Pa) at baseline was 0.93 ± 0.05 mm Hg. Using intravenous adenosine infusion, the mean FFR measured with engaged vs disengaged non-side-hole guide catheters was 0.87 ± 0.09 vs 0.83 ± 0.10, respectively (mean difference, 0.039 ± 0.04; P<.001). The mean FFR with engaged vs disengaged side-hole guide catheters was 0.85 ± 0.10 vs 0.83 ± 0.10 (mean difference, 0.020 ± 0.02; P<.001). The mean difference in FFR measurements was 0.024 ± 0.03 (P<.001) among engaged guide catheters and 0.005 ± 0.03 (P=.47) among disengaged guide catheters. CONCLUSIONS: When FFR measurements are performed with engaged guide catheters, side-hole catheters provide lower measurements. When FFR measurements are obtained with disengaged guide catheters, they are even lower and similar between guide catheter types.

Impact of crossing technique on the incidence of periprocedural myocardial infarction during chronic total occlusion percutaneous coronary intervention.

OBJECTIVES: We sought to evaluate the impact of crossing strategy on the incidence of periprocedural myocardial infarction (PMI) during chronic total occlusion (CTO) percutaneous coronary intervention (PCI). BACKGROUND: The optimal technique for crossing coronary CTOs remains controversial. METHODS: We retrospectively examined the incidence of PMI among 184 consecutive patients who underwent CTO PCI at our institution between 2012 and 2015. Creatine kinase-myocardial band fraction (CK-MB) and troponin were measured before and after PCI in all patients. PMI was defined as CK-MB increase ≥3× upper limit of normal (ULN). RESULTS: Mean age was 65 ± 8 years, 98% of patients were men, 57% had diabetes mellitus, 36% were current smokers, 38% had prior heart failure, 31% had prior coronary artery bypass graft surgery (CABG), and 55% had prior PCI. The retrograde approach was used in 38% of cases. As compared with antegrade wire escalation and antegrade dissection/re-entry, use of the retrograde approach was associated with higher J-CTO (Multicenter CTO Registry of Japan) scores (P < 0.0001), higher frequency of moderate or severe calcification (P = 0.0061), longer CTO length (P < 0.0001), more frequent proximal cap ambiguity (P < 0.0001), and lower technical (P = 0.0007) and procedural (P = 0.0014) success. The frequency of PMI for the antegrade-only and retrograde cases was 10% and 33%, respectively (P = 0.0001). On multivariate analysis, use of the retrograde approach and moderate/severe calcification were independently associated with higher incidence of PMI. CONCLUSIONS: As compared with antegrade-only crossing techniques, the retrograde approach is used in patients with more complex anatomy but may carry higher risk for PMI. © 2016 Wiley Periodicals, Inc.

Impact of Crossing Strategy on Intermediate-term Outcomes After Chronic Total Occlusion Percutaneous Coronary Intervention.

BACKGROUND: There is ongoing controversy about the optimal crossing strategy selection for chronic total occlusion (CTO) percutaneous coronary intervention (PCI), especially regarding the relative merits of antegrade dissection/re-entry and the retrograde approach. METHODS: We retrospectively examined the clinical outcomes of 173 consecutive patients who underwent successful CTO PCI at our institution between January 2012 and March 2015. RESULTS: The mean age was 65 ± 8 years, and 98% of the patients were men with a high prevalence of diabetes (60%), previous coronary artery bypass grafting (CABG) (31%), and previous PCI (54%). The successful CTO crossing strategy was antegrade wire escalation in 79 patients (45.5%), antegrade dissection/re-entry in 58 patients (33.5%), retrograde wire escalation in 11 patients (6.4%), and retrograde dissection and re-entry in 25 patients (14.5%). The retrograde approach was more commonly used in lesions with interventional collaterals (P < 0.0001), moderate/severe calcification (P = 0.02), blunt stump (P = 0.01), and a higher Japan Chronic Total Occlusion score (P = 0.0002). Use of dissection and re-entry (both antegrade and retrograde) was associated with bifurcation and the distal cap (P = 0.004), longer CTO occlusion length (P < 0.0001), and longer stent length (P < 0.0001). Median follow-up was 11 months. The 12-month incidence of death, myocardial infarction, and the composite of acute coronary syndrome/target lesion revascularization/target vessel revascularization was 2.5%, 4.9%, and 24.4%, respectively, and was similar with intimal and subintimal crossing strategies. CONCLUSIONS: Antegrade dissection/re-entry and retrograde approaches are frequently used during CTO PCI and were associated with similarly favorable intermediate-term outcomes as antegrade wire escalation.

Predictors and Outcomes of Side-Branch Occlusion in Coronary Chronic Total Occlusion Interventions.

OBJECTIVES: We investigated whether side-branch loss during chronic total occlusion (CTO) percutaneous coronary intervention (PCI) could adversely impact clinical outcomes. BACKGROUND: Side-branch occlusion during PCI has been associated with periprocedural myocardial infarction and higher incidence of major adverse cardiac event (MACE), but has received limited study in CTO-PCI. METHODS: We retrospectively reviewed the medical records and coronary angiograms for 109 consecutive CTOPCI cases performed at our institution during 2012 and 2013. Post-PCI patency of ≥1 mm diameter side branches and associated clinical outcomes were assessed. RESULTS: Mean age was 65 ± 8 years and 99.1% of the patients were men. The CTO target vessel was the right coronary artery (54%), circumflex (26%), and left anterior descending artery (20%). Side-branch loss occurred in 28 cases (25.7%) due to antegrade dissection/reentry (n = 9), retrograde dissection/reentry (n = 5), stenting over the branch (n = 12), and dissection during antegrade crossing attempts (n = 2). Recanalization of the occluded side branch was pursued in 8 cases (28.6%) and was successful in 4 patients. Patients with side-branch loss had higher post-PCI increase in CK-MB levels (8.4 ng/mL [interquartile range, 2.7-33.5 ng/mL] vs 1.8 ng/mL [interquartile range, 0.025-6.775 ng/mL]; P<.001) and higher 12-month incidence of all-cause death (17.3% vs 2.8%; P=.02) and cardiovascular death (7.4% vs 0.0%; P=.02). CONCLUSIONS: Side-branch loss occurs in approximately 1 in 4 CTO-PCIs and is associated with higher risk for periprocedural myocardial infarction and higher mortality.