ALBERT

Description: Cu 2 ZnSn(S,Se) 4 (CZTSSe) solar cells typically exhibit high short-circuit current density ( J sc ), but have reduced cell efficiencies relative to other thin film technologies due to a deficit in the open-circuit voltage ( V oc ) , which prevent these devices from becoming commercially competitive. Recent research has attributed the low V oc in CZTSSe devices to small scale disorder that creates band tail states within the absorber band gap, but the physical processes responsible for this V oc reduction have not been elucidated. In this paper, we show that carrier recombination through non-mobile band tail states has a strong voltage dependence and is a significant performance-limiting factor, and including these effects in simulation allows us to simultaneously explain the V oc deficit, reduced fill factor, and voltage-dependent quantum efficiency with a self-consistent set of material parameters. Comparisons of numerical simulations to measured data show that reasonable values for the band tail parameters (characteristic energy, capture rate) can account for the observed low V oc , high J sc , and voltage dependent collection efficiency. These results provide additional evidence that the presence of band tail states accounts for the low efficiencies of CZTSSe solar cells and further demonstrates that recombination through non-mobile band tail states is the dominant efficiency limiting mechanism.

Description: Duvelisib (IPI-145), a dual inhibitor of phosphoinositide 3-kinase (PI3K)-δ and -γ, has shown clinical activity in treatment-naïve and relapsed/refractory chronic lymphocytic leukemia (CLL) patients. Clinically, duvelisib results in a redistribution of malignant B cells and concomitant reduction in nodal enlargement. These effects are believed to be due to important roles of PI3K- δ and -γ in CXCL12-mediated CLL cell migration (Peluso 2014), cytokine-induced CLL B-cell proliferation, and BCR-stimulated B-cell survival (Balakrishnan 2015). Additional data suggest an effect of duvelisib on the tumor supporting cells of the CLL microenvironment. This includes preclinical studies demonstrating that PI3K-γ inhibition blocks normal T cell migration toward tumor chemokines and prevents murine bone marrow-derived M2 macrophage polarization (Peluso 2014), as well as clinical data in CLL patients receiving duvelisib showing reduced serum levels of myeloid and T cell-secreted cytokines and chemokines (Douglas 2015). To further characterize duvelisib's effect on CLL cells and the tumor microenvironment (TME), a murine xenograft model using primary human CLL cells was employed. We first studied duvelisib's effect on CLL B- and T-cell migration in vivo. CLL PBMCs (n=2; 1 IGHV unmutated (U)-CLL, 1 IGHV mutated (M)-CLL) pre-treated with duvelisib for 48 hours were injected retro-orbitally into NOD-scid IL2Rgammanull (NSG) mice. B- and T-cell localization in tissues and circulation was studied 1 and 24 hours post-injection. Duvelisib treatment (1000 nM) prevented the egress of CLL B and T cells from the circulation into the spleen, indicating impaired homing of CLL B and T cells. To better define the effect of duvelisib on T-cell migration, T cells from CLL patients (n=3; 2 U-CLL, 1 M-CLL) treated ex vivo with duvelisib at 1, 10, 100 and 1000 nM were injected into mice and analyzed for their trafficking 24 hours later. Inhibition of T-cell homing to spleen was dose dependent, with only 100 and 1000 nM having significant effects. Given duvelisib's cellular IC50s for PI3K isoforms, these results suggest that impaired T-cell migration is due to PI3K-γ inhibition, and studies with isoform-selective PI3K-δ and PI3K-γ inhibitors are currently underway to examine this possibility. The effect of duvelisib on CLL T-cell proliferation was evaluated after in vitro activation with anti-CD3/28 Dynabeads plus IL2 (n=6; 3 U-CLL, 3M-CLL). In duvelisib treated cells, CD4+, but not CD8+, T-cell proliferation was inhibited at doses of 100 and 1000 nM, suggesting a role for PI3K-γ. The effects of duvelisib on CLL B- and T-cell growth in vivo (n=4; 2 U-CLL, 2 M-CLL) were then studied. Autologous CLL T cells were stimulated as above and injected with CLL PBMCs into NSG mice. Animals treated orally with duvelisib for 3 weeks at 100 mg/kg/day had preferentially reduced CD4+ T-cell recovery from spleens, thereby decreasing the CD4 to CD8 ratio. In each case, duvelisib treatment reduced the number of splenic CLL B cells. This reduction reflected inhibition of both CLL cell proliferation and survival, since duvelisib treatment decreased the percentage of cycling CLL cells and increased the percentage of apoptotic B cells. Thus, duvelisib may target CLL B-cell growth directly, or indirectly by inhibiting the support of CD4+ T cells in the TME. The potential effect of duvelisib on the tumor-supporting myeloid compartment was also tested. Because of limited human myeloid-cell engraftment in our NSG model, we studied the effect of duvelisib on murine macrophages. Mice receiving duvelisib had reduced numbers of splenic CD11b+ GR-1low LY-6Clow LY-6Gneg macrophages compared to controls, suggesting duvelisib altered macrophage development. Prior in vitro studies demonstrated inhibition of CLL B-cell survival and proliferation by duvelisib, as well as blockade of T-cell migration and M2 macrophage polarization (Balakrishnan 2015; Peluso 2014). Our current in vivo studies further support duvelisib's effect on CLL B-cell growth and survival through inhibition of cellular homing to supportive tissue niches and alterations in the TME. The latter, in part, is through suppression of T-cell support and alterations in the macrophage compartment. Overall, these preclinical results suggest that inhibition of PI3K-δ and PI3K-γ by duvelisib affects CLL cell survival through direct and indirect mechanisms. Disclosures McGovern: Infinity Pharmaceuticals, Inc.: Employment. Kutok:Infinity Pharmaceuticals, Inc.: Employment.

Description: HMGA2 is a member of the high-mobility group A family and plays a role in the regulation of gene transcription and chromatin structure. HMGA2 is a validated target of the let-7 family of miRNAs. Let-7 miRNAs are highly regulated in erythroid cells during the fetal-to-adult developmental transition (1). Recent studies demonstrated that the LIN28 -let-7 axis mediated up-regulation of fetal hemoglobin (HbF) expression to 〉30% of the total globin levels in cultured erythroblasts from adult humans (2) and the amelioration of hypoxia-related sickling of cultured mature erythrocytes from pediatric patients with sickle cell disease (3). Interestingly, increased expression of endogenous HbF in a patient receiving gene therapy was also associated with truncated HMGA2 protein expression after lentiviral integration and disruption of let-7 targeting at the HMGA2 gene locus (4). Therefore, we hypothesized that HMGA2 may be involved in fetal hemoglobin regulation as a downstream target of the let-7 miRNAs. To study the effects of HMGA2 upon erythropoiesis and globin expression, lentiviral constructs were designed for let-7 resistant expression of HMGA2 driven by the erythroid-specific gene promoter region of the human SPTA1 gene (HMGA2 -SPTA1-OE), with a matched empty vector control. Transductions were performed in CD34+ cells from four adult healthy volunteers cultivated ex vivo in erythropoietin-supplemented serum-free media for 21 days. Overexpression of HMGA2 was confirmedby Q-RT-PCR (control: below detection limits; HMGA2 -SPTA1-OE: 2.51E+04 ± 3.44E+04 copies/ng) and Western blot analyses at culture day 14. Cell counting revealed no significant changes between HMGA2 -SPTA1-OE and control (empty vector) transductions at culture day 14. Terminal maturation with loss of CD71 from the erythroblast cell surface and enucleation assessed by thiazole orange staining were analyzed in the control and HMGA2 -SPTA1 -OE samples at the end of the culture period. Globin genes expression levels were evaluated for HMGA2 -SPTA1-OE by Q-RT-PCR. HMGA2 -SPTA1-OE caused a significant increase in gamma-globin mRNA expression levels compared to controls (control: 5.02E+05 ± 8.62E+04 copies/ng; HMGA2 -SPTA1-OE: 1.45E+06 ± 7.31E+05 copies/ng; p=0.037). Consistent with the increase in gamma-globin mRNA levels, HPLC analyses at culture day 21 demonstrated modest but significant increases in HbF levels in HMGA2 -SPTA1-OE compared to controls (HbF control: 5.41 ± 2.15%; HMGA2 -SPTA1-OE: 16.53 ± 4.43%; p=0.006). Possible effect(s) and downstream mechanism(s) triggered by HMGA2 -SPTA1-OE were investigated. Q-RT-PCR analyses demonstrated no significant changes in the let-7 family of miRNAs in HMGA2 -SPTA1-OE compared to controls. Expression patterns of several transcription factors such as BCL11A, KLF1, SOX6 and GATA1 were investigated by Q-RT-PCR and no significant changes were detected in HMGA2 -SPTA1-OE compared to controls. While BCL11A mRNA levels were decreased by HMGA2 -SPTA1 -OE, the differences did not reach statistical significance (control: 4.26E+02 ± 8.18E+01 copies/ng; HMGA2 -SPTA1 -OE: 2.84E+02 ± 1.48E+02 copies/ng; p=0.104). However, nuclear BCL11A protein levels assessed by Western analysis were suppressed in HMGA2 -SPTA1 -OE. In summary, these results demonstrate that HMGA2, a validated target of let-7 miRNAs, causes moderately increased gamma-globin gene and protein expression in human erythroblasts, and reduces levels of BCL11A protein. These data thus support the notion that suppression of let-7 miRNAs increases fetal hemoglobin, in part, by the targeting of erythroblast HMGA2 mRNA. (1) Noh SJ et al. J Transl Med. 7:98 (2009). (2) Lee YT et al. Blood. 122:1034-41 (2013). (3) Vasconcellos JF et al. PLoS One. 9:e106924 (2014). (4) Cavazzana-Calvo M et al. Nature. 467:318-22 (2010). Disclosures No relevant conflicts of interest to declare.

Description: Key Points The G9a methyltransferase inhibitor UNC0638 increased pancellular expression of HbF to levels greater than 30% in adult human erythroblasts. UNC0638 altered globin locus epigenetic status/protein occupancy favoring LCR interaction with fetal genes at the expense of adult genes.

Description: Recent studies demonstrated that IGF2BP1 over-expression (IGF2BP1-OE) in adult erythroblasts has robust effects on fetal hemoglobin (HbF; 〉65% of the total globin levels), accompanied by reversal of the beta-like globin expression patterns to a fetal-like phenotype. Here we investigated if another member of the insulin-like growth factor 2 mRNA-binding protein family, IGF2BP3, also has potential for HbF regulation that may be useful for therapeutic application among patients with beta-hemoglobin disorders. The developmental pattern and expression levels for IGF2BP3 were initially determined in cord blood versus adult blood CD34(+) samples cultivated ex vivo in erythropoietin-supplemented serum-free media for 21 days. RNA samples were collected at culture day 14 and expression levels were measured by qRT-PCR. IGF2BP3 showed a developmentally regulated expression pattern similar to IGF2BP1 (IGF2BP1: cord blood: 1.3.E+03 ± 4.3.E+02 and adult blood: below detection limits; IGF2BP3: cord blood: 5.8.E+02 ± 2.4.E+02 and adult blood: below detection limits). These results were confirmed in vivo by comparing human fetal liver to adult bone marrow samples (IGF2BP1: fetal liver: 3.5.E+02 ± 5.7.E+01, adult bone marrow: below detection limits and IGF2BP3: fetal liver: 2.0.E+01 ± 2.7.E+00, adult bone marrow: below detection limits). To investigate the effects of IGF2BP3 upon erythropoiesis and globin expression, a lentiviral construct was designed for expression of IGF2BP3 driven by the erythroid-specific gene promoter region of the human SPTA1 gene (IGF2BP3-OE), with a matched empty vector control. Transductions were performed in CD34(+) cells from four adult healthy volunteers cultivated ex vivo in erythropoietin-supplemented serum-free media for 21 days. Over-expression of IGF2BP3 was confirmedby qRT-PCR and Western blot analyses at culture day 14. IGF2BP3-OE cells maintained their ability to differentiate and enucleate ex vivo compared to donor-matched controls. The expression levels of globin genes were evaluated at culture day 14 by qRT-PCR and showed that IGF2BP3-OE caused significantly increased gamma-globin expression levels compared to control transductions (control: 7.7.E+05 ± 1.7.E+05; IGF2BP3-OE: 8.4.E+06 ± 3.2.E+06; p=0.018). Consistent with increased gamma-globin, HbF rose to moderately high levels upon IGF2BP3-OE (control: 4.0 ± 2.1%; IGF2BP3-OE: 18.6 ± 1.0%; p=0.0021). In addition, the expression pattern of the erythroid transcription factor BCL11A was investigated by qRT-PCR at culture day 14 and no significant changes were observed (control: 5.6.E+02 ± 2.7.E+02; IGF2BP3-OE: 6.7.E+02 ± 3.5.E+02; p=0.694). However, minor decreases in BCL11A protein levels were detected by Western analysis. These results demonstrate that IGF2BP3 is developmentally regulated in human erythroid tissues with silencing during the fetal-to-adult transition. However, the effects of IGF2BP3-OE on HbF levels were less robust when compared to IGF2BP1-OE in cultured adult erythroblasts. Disclosures No relevant conflicts of interest to declare.

Description: Polymerization of sickle cell hemoglobin S (HbS) is recognized as a key event in the pathophysiology of sickle cell disease (SCD). Repeated HbS polymerization promotes an altered red blood cell (RBC) membrane, hemolysis, and microparticle (MP) formation, which have been shown to play significant roles in the interaction of RBCs with vascular endothelium and progression of vaso-occlusive events. Circulating RBC-derived MPs are elevated in SCD patients and they release a significant portion of their contents including oxidized HbS and heme to the cells of the vasculature. We have recently reported that free HbS oxidizes faster, remains locked in a highly oxidizing form (ferryl) longer, and loses heme faster than normal HbA (Kassa et al., J Biol Chem 290: 27939, 2015). The contributions of HbS higher oxidation states (ferric and ferryl heme) to MP formation, membrane alterations, and heme loss are poorly defined in SCD. RBC-derived MPs (ranging in size between 100-300 nm in diameter) generated by sheer stress or isolated by ultracentrifugation from the plasma (circulating) of SCD patients (N=6), ethnically matched control subjects (N=5), humanized transgenic sickle mice (Townes-SS, N=4), and control wild-type mice (Townes-AA, N=4) were identified by flow cytometry using CD235a glycophorin antibody and annexin V for externalized phosphatidylserine (PS). Time courses of Hb oxidation, obtained during 30 hour incubations of mouse or human MPs were biphasic. The initial levels of oxidized (ferric) Hb (30 to 45%) were slightly reduced within the first ~10 hours, likely due to the presence of RBC residual reductive enzymes within MPs. This was followed by a second phase in which Hb oxidation (ferric Hb) increased linearly and uncontrollably to 65 to 75% of total Hb. SCD MP's contained highly reactive ferryl Hb intermediates, carbonylated membrane proteins, and phosphorylated band 3 proteins. Quantitative proteomic analysis indicated a higher level of protein oxidation in MPs derived from SCD mice and patients. Five-fold higher levels of irreversibly oxidized βCys93 oxidation were found in untreated versus hydroxyurea-treated SCD patients. Intriguingly, HbS β subunits from SCD MPs were ubiquitinated and MPs isolated from untreated SCD patients had 25-fold higher ubiquitination levels than hydroxyurea-treated SCD patients that were comparable to normal controls. MP ubiquitination levels were correlated with HbS and an overall increase in MP oxidative stress, and inversely correlated with HbF. Compared to respective control MPs, incubation of either mice or human SCD MPs with human endothelial cells (HUVEC) activated apoptotic pathways and impacted cellular bioenergetic parameters by lowering mitochondrial oxygen consumption rates to a greater degree in a manner that was correlated with the redox state of Hb iron within MPs. Human endothelial cells incubated with SCD MPs showed greater intracellular reactive oxygen species production and heme oxygenase-1 induction. In summary, Hb transformation to higher oxidation forms is markedly increased in MPs generated from SCD mice and patients, which when incubated with endothelial cells, lead to mitochondrial dysfunction and apoptotic cell death. These mechanistic analyses of RBC-derived SCD microparticles suggest potential anti-oxidative reducing modalities that may interrupt MP heme-mediated pathophysiology in patients with SCD. Disclosures Belcher: Cydan/Imara: Research Funding; CSL-Behring: Research Funding. Vercellotti:CSL-Behring: Research Funding; Imara: Research Funding.

Description: Background: The 1000 Genomes Project provides a database of over 80 million genomic variants found across 2504 individuals from 26 populations. A current priority of the genomics field is to design information systems to translate this knowledge into clinical significance and patient care. The applications and advantages of red blood cell (RBC) antigen prediction through genotyping are widely accepted in transfusion medicine. Current technologies address a limited number of single nucleotide polymorphisms (SNPs) in 12 blood group genes, and our background knowledge of RBC phenotype distribution is often limited to a few populations. We analyzed the 1000 Genomes database with 4 objectives: 1) determine allele distributions of 46 blood group-related genes across the 5 genotyped superpopulations: Africa, East Asia, Europe, South Asia and the Americas; 2) identify possible new blood group alleles and their geographic association; 3) determine the feasibility of blood group genotyping by NGS; and 4) establish a scaffold of chromosomal coordinates to interpret NGS output files into a predicted RBC phenotype. Results: From the initial list of 46 blood group-related genes, we eliminated the five genes with known rearrangements and focused only on regions that met the strict criteria for accessibility through short, paired-end NGS reads (77% of 80.4kb). We mapped over 800 known alleles in coding and non-coding regions, and documented the 80 variants that were both present in the 1000 Genomes database and met the strict accessibility criteria. Sixty-four of these 80 variants are not addressed by current RBC genotyping technology. All 80 variants, including the ACKR1 promoter silencing mutation, are located within exon pull-down boundaries. The average low-coverage sequencing depth was 18,424x, with exome-sequencing confirmation at 65.7x depth. Twenty-three alleles had at least one novel population distribution, such as documentation of the Kpaallele for the first time in Africa and South Asia. From a total of 30 novel blood group continental frequencies, 14 correspond to a newfound presence in South Asia. 1000 Genomes identified a total of 926 missense mutations in blood group genes that met strict NGS mapping criteria, as well as multiple deletions. Two novel missense mutations in ERMAP and SLC14A1 are classified as likely antigenic, since they target the same amino acids responsible for the SCER- and Cr(a-) alleles. Six novel deletions involving the Lewis, H, Cromer, Indian and OK systems are also classified as likely-deleterious after careful analysis. For example, a novel in-frame 24bp deletion in SLC14A1 eliminates part of the intracytoplasmic tail, which is required for membrane localization and includes the 28G residue that defines JK*01W.03. Thus, this novel deletion is predicted to alter Kidd protein expression. The 8 novel alleles are distributed throughout the five superpopulations but are most frequently found in Africa. Four standard bioinformatics programs named SIFT, PolyPhen-2, Mutation Taster, and Mutation Assessor failed to detect half of the control known blood group alleles and thus are not adequate for the analysis of novel blood group variants in the transfusion medicine context. Conclusions: NGS can allow comprehensive, fast, and high-throughput RBC antigen prediction. All queried blood group alleles are amenable to targeted exome sequencing, and 77% of blood group coding sequences can be addressed with a short, paired-end NGS strategy. Based on 1000 Genomes, we created a database of the worldwide distribution of 80 known and 8 novel blood group variants, along with their chromosomal coordinates in the hg19 and GRCh38 assemblies. This database is the scaffold for the creation of a new transfusion medicine bioinformatics pipeline that will translate NGS .vcf output files into a predicted RBC phenotype. New algorithms that focus on exposed peptides and antigenicity are required for the analysis of novel variants identified by NGS in the immunohematology context. Disclosures No relevant conflicts of interest to declare.