Robert Molokie - Academia.edu (original) (raw)

Papers by Robert Molokie

Blood, Nov 5, 2021

Increased levels of Fetal Hemoglobin (HbF) reduce the symptoms of sickle cell disease (SCD) and l... more Increased levels of Fetal Hemoglobin (HbF) reduce the symptoms of sickle cell disease (SCD) and lengthen the life span of patients. New, more effective pharmacological agents that can be safely administered long term to increase HbF levels in SCD patients are highly sought. Expression of the γ-globin gene in adult erythroid cells is normally repressed by the recruitment of multi-protein co-repressor complexes to the γ-globin promoter by sequence-specific DNA binding proteins including BCL11A, LRF1 and TR2/TR4. Enzymes contained within these co-repressor complexes, such as DNMT1, LSD1, G9A, and HDACs, modify the chromatin surrounding the γ-globin promoter by catalyzing repressive epigenetic modifications to both histones and DNA. Small molecule pharmacological inhibitors of these enzymes are potent inducers of HbF in various in cell culture and animal models and in SCD patients, but the use of these drugs in patients has been hindered by their dose-dependent effects on hematopoietic differentiation. An alternative strategy to the use of these pharmacological inhibitors to increase HbF would be to employ pharmacological activators that increase the activity of proteins that positively promote γ-globin expression. Previous studies have shown that pharmacological activators of the Sirtuin 1 protein deacetylase increased γ-globin expression in cultured human CD34+ erythroid progenitor cell cultures (Dai et al; Am J Hematol 92:1177-1186, 2017). Because Sirtuin deacetylase activity is dependent upon nicotinamide adenine dinucleotide (NAD) as a co-factor, we tested the hypothesis that increased concentrations of nicotinamide, an NAD precursor, would also increase γ-globin expression. Baboon bone marrow derived CD34+ erythroid progenitor cells from 4 individual baboons were cultured on AFT024 monolayers for 14 days in the presence and absence of varying concentrations of nicotinamide. Globin chain expression was measured in cell lysates by high performance liquid chromatography (HPLC). Nicotinamide (500μM) appeared to increase γ-globin 2 fold (0.015±0.098 γ/γ+β) compared to untreated controls (0.072±0.04 γ/γ+β; n=4; p<0.08). Because the nicotinamide levels used in this experiments are higher than can be easily achieved by dietary supplementation, additional experiments were performed to test the effect of P7C3-A20, an allosteric activator of nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in the NAD synthesis, on γ-globin expression. Addition of P7C3-A20 (2.5μM) to CD34+ erythroid progenitor cultures on d1, 4, 7, and 10 increased γ-globin 2.7 fold (0.247±0.10 γ/γ+β) compared to vehicle-treated controls (0.090±0.06 γ/γ+β; n=5; p<0.01). P7C3-A20 treatment did not affect cell viability or growth at concentration< 2.5μM and dose-response experiments showed increased γ-globin in cultures treated with submicromolar concentrations of the drug. Addition of P7C3-A20 to cultures on days 1 and 4 resulted in near maximal stimulation of γ-globin expression with lesser effects when the drug was added on later days (d4 and7 or d7 and 10) strongly suggesting that the drug targets cells at an early stage of differentiation. Additional experiments showed that the effect of P7C3-A20 (2.5μM) in combination with either the DNMT1 inhibitor decitabine (DAC) or the LSD1 inhibitor tranylcypromine (TCP) resulted in a greater than additive effects on γ-globin expression in the absence of cytotoxicity (Figure 1). In conclusion, the NAMPT activator P7C3-A20 increased γ-globin expression in baboon CD34+ erythroid progenitor cells with greater than additive effects in combination with DAC or TCP. P7C3-A20 has potent in vivo effects as a neuroprotective drug in mouse models and non-human primates. Therefore, the potential of this drug for in vivo HbF induction warrants further investigation. Figure 1 Figure 1. Disclosures Saunthararajah: EpiDestiny: Consultancy, Current holder of individual stocks in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties.

Blood, Dec 2, 2016

Increased levels of fetal hemoglobin (HbF) lessen the severity of symptoms and increase the life ... more Increased levels of fetal hemoglobin (HbF) lessen the severity of symptoms and increase the life span of patients with sickle cell disease. New and more effective strategies to increase HbF are needed because current therapies are ineffective in a significant proportion of patients. The lysine-specific demethylase, LSD1, an enzyme that demethylates Histone H3 mono- and dimethyl- K4 and K9 residues, is a component of the DRED co-repressor complex that represses the γ-globin gene (Cui et al, Mol Cell Biol 31:3298, 2011). Our laboratory has recently shown that RN-1, a pharmacological inhibitor of LSD1, increases γ-globin expression in sickle cell disease (SCD) transgenic mice (Rivers et al, Exp Hematol 43:546, 2015; Cui et al, Blood 126:386, 2015) and in baboons (Rivers et al, Haematol 101:688, 2016), widely acknowledge as the best animal model to test the activity of HbF-inducing drugs. To evaluate the safety and efficacy of RN-1, two normal, non-anemic baboons were treated for an extended period with RN-1 (PA8695, 264d; PA8698, 278d; 0.25mg/kg/d; 5d/wk, sc) and the effect on HbF, F cells, and hematological parameters evaluated weekly. Both animals exhibited weight gain (PA8695: 14.4%; PA8698: 20%) during the course of the study. F retics were increased 8-10 fold by the second week (d9) and were maintained at high levels throughout the course of the study (PA8695: 55.7±17.7% (mean±SD), median (M)=59.0%; PA8698: 56.4±14.5%, M=56.9%). F cell levels increased until d169 and were maintained thereafter at levels 18-25 times greater than pre-treatment (PA8695: 54.5±3.3%, M=54.2%; PA8698: 51.7±3.2%, M=51.4%). HbF levels also increased until d169 and were also maintained thereafter at levels 10-12 times greater than pre-treatment (PA8695: 12.8±1.7%, M=12.1%; PA8698: 11.4±1.4%, M=11.5%). Elevated levels of γ-globin chain synthesis were observed in the peripheral blood on multiple days (d162, d190, d267) of treatment (PA8695, 0.28±0.08 γ/γ+β;PA8698, 0.26±0.08 γ/γ+β). RT-PCR analysis showed that γ-globin mRNA levels were increased 9-22 fold (p<0.01) in FACS-purified CD105+ CD117+/- glyA+ BM erythroid precursor subpopulations of RN-1 treated baboons compared to normal baboons. Absolute neutrophil counts showed no overall decline compared to pre-treatment (PA8695: pre-treatment=2110/μL, post-treatment=3118±1452/μL, M=2765/μL; PA8698: pre-treatment=2690/μL, post-treatment=2936±696/μL, M=2460/μL) although variations were observed. In PA8695 the ANC declined below 1500/μL twice (1490, 1160) and five times (1250, 1410, 1420, 1330, 1000) in PA8595. Monocytes increased 2-3 fold in each animal (PA8695: pre-treatment=100/μL, post-treatment=252±97/μL, M=246/μL; PA8698: pre-treatment=161/μL, post-treatment=425±319/μL, M=347/μL). Hemoglobin (Hb), RBC, and hematocrit (HCT) levels exhibited small overall decreases during the course of treatment but remained within the normal range. Decreases in RBC, Hb, and HCT were associated with blood loss during menstruation (PA8695) and following an accidental laceration of the perineal swelling (PA8698). Rapid recovery was observed in both animals. Significant changes in MCV, MCH, and MCHC during treatment were not observed. Platelet levels decreased approximately 40% in each animal but nevertheless were maintained within the normal range (PA8695: pre-treatment=351 X 103/μL, post-treatment=236±64 X 103/μL, M=219 X 103/μL; PA8698: pre-treatment=224 X 103/μL, post-treatment=143±78 X 103/μL, M=119 X 103/μL). No significant differences in either PT or aPTT assays were observed compared to normal baboons. In vitro platelet activation assays performed to investigate effects on platelet function showed that the fraction of platelets expressing P-selectin (CD62P) on the surface following…

Seminars in Hematology, 2021

Human hemoglobin switching describes the highly regulated, sequential expression of the five β-li... more Human hemoglobin switching describes the highly regulated, sequential expression of the five β-like globin genes (HBE, HBG2, HBG1, HBD and HBB) of the human β-globin gene complex. The sequential activation of these β or β-like globin genes during human development from early embryonic through late fetal (‘adult’) stages, and during erythroid maturation, occurs in an order corresponding to their 5’ to 3’ location on chromosome 11. The β-hemoglobinopathies are the most common inherited diseases in humanity, and are diseases of mutated HBB or its altered regulation. Since the other β-like globin genes can potentially substitute for defective HBB, much translational research is directed toward understanding and manipulating sequential activation at the human β-globin gene complex to treat β-hemoglobinopathies. Non-human primates provide a vital contribution to such efforts because of their recapitulation of the developmental/maturational switch in hemoglobin production as observed in humans (mice do not model this switch). Valuable insights into druggable epigenetic forces that mediate the switch have been thereby gained. We review important lessons learned in non-human primates, complemented by other studies, and suggest rational next steps.

Current developments in nutrition, Jun 1, 2019

Haematologica, Dec 1, 2019

Blood, Nov 5, 2020

Pharmacological treatments designed to increase Fetal Hemoglobin (HbF) levels offer great promise... more Pharmacological treatments designed to increase Fetal Hemoglobin (HbF) levels offer great promise to alleviate the symptoms and improve the lifespan of the vast numbers of patients afflicted with sickle cell disease (SCD) and β-thalassemia. Hydroxyurea can increase HbF, but a large fraction of patients with SCD do not respond to the drug. DNMT1 and LSD1 inhibitors are the most powerful drugs to increase HbF but are limited by side effects that include neutropenia, thrombophilia and/or thrombocytopenia. The development of new, more effective, and safer pharmacological strategies to augment HbF levels in the blood thus continues to be an important goal. Previous studies have shown that γ-globin gene expression is dynamically regulated during erythroid differentiation (Papayannopoulou et al PNAS 74:2923-2927, 1977). The proportion of γ-globin gene expression is higher at earlier stages (BFUe) of erythroid differentiation than at more advanced stages (CFUe). Therefore, we suggest the hypothesis that expansion of primitive, less differentiated progenitors might favor increased γ-globin, particularly when combined other HbF-inducing drugs. To investigate this hypothesis, we have tested whether nicotinamide (NAM), the major NAM metabolite 1-methylnicotinamide (1-mNAM), and N'-methylnicotinamide (N'-mNAM), a chemical derivative of NAM, can foster expansion of erythroid colony-forming cells (BFUe and CFUe) and increase γ-globin expression of cultured baboon CD34+ cells. Previous observations have shown that NAM facilitates in vitro expansion of cord blood CD34+ cells and enhanced long term engraftment in transplanted recipients (Horwitz et al J Clin Invest 124:3121, 2014). Contrasting effects of NAM, 1-mNAM, and N'-mNAM on differentiation and proliferation of the murine erythroleukemia cell line (MEL) have been previously reported (Terada et al PNAS 76:6414, 1979; Kuykendall et al Toxicol In Vitro 21:1656, 2007). While both NAM and N'-mNAM induced MEL cell differentiation, N'-mNAM was far more potent. In contrast, 1-mNAM increased cell proliferation, reduced spontaneous differentiation, and blocked differentiation induced by NAM and N'-mNAM. The effect of all three forms of NAM was examined using bone marrow (BM) CD34+ cells from a pre-clinical non-human primate large animal model. To test the effect of NAM, 1-mNAM, and N'-mNAM on expansion of erythroid colony-forming cells, the agents (5mM) were added to liquid cultures of baboon CD34+ bone marrow cells previously expanded for 5 days in serum-free expansion media (SFEM). Colony assays were performed on d8. In two experiments total erythroid colonies (BFUe and CFUe) were 2 fold higher in cultures treated with 1-mNAM compared to untreated controls (p<0.05) while no effect was observed in cultures treated with NAM. No colonies were observed in cultures treated with N'-mNAM (Figure 1A). Observation of Wright's stained cytospin preparations showed extensive erythroid differentiation on d8 in cells treated with N'-mNAM (Figure 1B). The effect of NAM, 1-mNAM, and N'-NAM on γ-globin expression was tested in baboon CD34+ cells grown in co-culture with the AFT024 cell line. NAM, 1-mNAM, or N'-mNAM (5mM) were added to cultures on d7. Expression of γ- and β-globin mRNA was measured by RT-PCR on d17. Increased γ-globin expression (0.57±0.04 γ/γ+β)) was observed in cells treated with N'-mNAM on d7 compared to untreated controls (0.20±0.09 γ/γ+β; p<0.001). NAM and 1-mNAM had no significant effect on γ-globin gene expression (Figure 1C). These results thus show that while erythroid colonies are increased by 1-mNAM, N'-mNAM is a potent inducer of erythroid differentiation and increases γ-globin expression in primary cultures of baboon CD34+ cells. In conclusion, 1-mNAM and N'-mNAM have contrasting effects on erythroid differentiation in primary baboon CD34+ cell cultures, confirming previous experiments in the MEL cell line. Future experiments are planned to test the effect of these agents on HbF in the baboon. Disclosures Saunthararajah: EpiDestiny: Consultancy, Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties.

Blood, Dec 6, 2014

Increased levels of fetal hemoglobin (HbF) lessen the severity of symptoms and increase the life ... more Increased levels of fetal hemoglobin (HbF) lessen the severity of symptoms and increase the life span of patients with sickle cell disease (SCD). Differences in DNA methylation of the γ-globin gene promoter between adult and fetal liver erythroid cells are highly associated with developmental differences in γ-globin expression. Mechanisms that establish and/or modulate DNA methylation of the γ-globin promoter during adult and fetal erythroid differentiation are important in the regulation of γ-globin expression. Pharmacological manipulation of DNA methylation increases HbF in nonhuman primates and SCD patients. Decitabine, a DNA methyltransferase inhibitor that demethylates DNA and increases HbF, is currently in clinical trials. Recent studies have shown that 5-hydroxymethylcytosine (5-hmC), an oxidative product of 5-methylcytosine (5-mC) catalyzed by activity of the TET dioxygenase family, is an intermediate in developmental processes that demethylate DNA. Previously we showed that the γ-globin gene promoter was demethylated during fetal liver erythroid differentiation and to a lesser extent during adult bone marrow (BM) erythroid differentiation. We have investigated the role of 5-hmC in the mechanism of γ-globin gene demethylation by analyzing 5-hmC levels at the HpaII site located at position -51 5’ to the γ-globin transcription start site using a T4-MspI assay in DNA isolated from FACS-purified subpopulations of baboon BM cells enriched for different stages of erythroid lineage differentiation. Levels of 5-hmC were >3 fold higher (p<0.001) in the CD117+CD36+ subpopulation enriched in CFUe (7.15+1.34%) compared to the terminal erythroid precursors (2.33+0.84%) showing that 5-hmC levels are dynamically regulated during erythroid differentiation. Although baboon BM erythroid subpopulations express both TET2 and TET3, higher levels of TET3 were observed in terminal erythroid precursors than in the more primitive CD117+CD36+ subpopulation. High levels of TET3 were also observed in FACS-purified erythroid cells derived from cultured CD34+ baboon BM, human peripheral blood, and human cord blood cells suggesting a role for TET3 in erythroid differentiation. To investigate the relationship between 5-hmC, 5-mC, and γ-globin expression, levels of γ-globin promoter 5-hmC and 5-mC were determined in purified erythroid cells derived from baboon BM CD34+ erythroid progenitors grown in culture…

Blood, Nov 5, 2021

The polymerization of deoxygenated HbS molecules in the red blood cells (RBCs) of patients with s... more The polymerization of deoxygenated HbS molecules in the red blood cells (RBCs) of patients with sickle cell disease (SCD) causes RBC destruction resulting in chronic pain, debilitating acute pain crises, strokes, multi-organ damage and a reduced life span. Therapeutic options remain limited. Bone marrow transplantation can be curative but is not an option for the majority of patients. Gene therapy interventions that also offer the promise of a cure are under investigation but are not likely to be available to the vast majority of patients in the near future. Hydroxyurea, the first drug approved for treatment of SCD, increases levels of Fetal Hemoglobin (HbF) that inhibit polymerization of HbS molecules but is not effective in all patients while a more powerful HbF-inducing drug, the DNA methyltransferase inhibitor decitabine has yet to be approved. L-glutamine, another approved therapeutic option, increases NAD redox potential and decreases reactive oxygen species (ROS) in the sickle RBCs to reduce symptoms. In our laboratory we have observed that increased ROS is associated with the retention of mitochondria in the SCD RBCs and have hypothesized that the abnormal presence of mitochondria in these cells is a major source of ROS (Jagadeeswaran et al Exp Hematol 50:46-52, 2017). In this investigation we have tested the hypothesis that chronic oral supplementation with nicotinamide, a direct precursor of NAD synthesis, would improve NAD redox potential, decrease mitochondrial retention and ROS in SCD RBCs, and reduce anemia in the SCD mouse model. The effect of nicotinamide was tested in SCD mice whose drinking water was supplemented for three months with 1% nicotinamide. The percentage of RBCs retaining mitochondria and the levels of ROS were determined by flow cytometric assays using the mitochondrial-specific dye TMRM and the ROS probe CM-H2DCFDA, respectively. In SCD mice receiving nicotinamide the fraction of RBCs retaining mitochondria was reduced 22.1% (p<0.05) and the level of ROS in RBCs was reduced 41% (p<0.01) compared to control SCD mice. The reticulocyte percentage was reduced 28% in nicotinamide-treated SCD mice compared to control SCD mice (p<0.01). The total RBC count was 30% higher (p<0.05) in nicotinamide-treated mice (6.61±0.76 X 10 6/μl) compared to control SCD mice (5.08±0.70 X 10 6/μl). Similar differences in hematocrit and total hemoglobin were also observed but failed to reach statistical significance. Total NAD levels were not significantly different in SCD mice receiving nicotinamide compared to control SCD mice (p<0.05), but the NADH/NAD total ratio was increased 2 fold (p<0.05). These results show that oral administration of high doses of nicotinamide decreases mitochondrial retention and ROS in SCD RBCs and improves NAD redox potential and anemia in SCD mice. These effects strongly suggest that additional studies be performed to investigate nicotinamide as a therapeutic option in SCD. Figure 1 Figure 1. Saunthararajah: EpiDestiny: Consultancy, Current holder of individual stocks in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties.

Experimental Hematology, Jun 1, 2023

Blood Advances, May 8, 2020

Blood, Nov 5, 2020

Sickle cell disease (SCD) is an inherited blood disorder that severely impacts the quality of lif... more Sickle cell disease (SCD) is an inherited blood disorder that severely impacts the quality of life and reduces the life expectancy of approximately 100,000 patients in the U.S. and millions worldwide. Elevated levels of Fetal Hemoglobin (HbF; α2γ2) reduce the severity of symptoms and lengthen the life span of patients with sickle cell disease by inhibiting deoxy HbS polymerization. Hydroxyurea (HU), the only FDA-approved drug shown to increase HbF, is not effective in a subset of patientsand importantly, in the refractory individuals the increased HbFis heterogeneously distributed within the erythrocyte population resulting in a large fraction of erythrocytes lacking protective levels. Simian primates such as the baboon are widely acknowledged as the best animal models for testing the ability of new drugs to increase γ-globin expression because results in baboons are predictive of effects in man due to conservation of the structure and developmental stage-specific regulation of the β-like globin genes in simian primates. Our previous studies in baboons have shown that the most powerful drugs for reactivation of HbF are DNMT1 and KDM1A inhibitors targeting enzymes located within the co-repressor complexes that act to establish and maintain repressive epigenetic modifications at the γ-globin promoter to repress γ-globin expression. Treatment of baboons with either decitabine, an inhibitor of DNMT1, or RN-1, an inhibitor of KDM1A, strongly stimulates HbF. Dose-limiting effects of these drugs include neutropenia, thrombocytopenia, and/or thrombophilia. In this investigation we have explored the hypothesis that a treatment regimen comprised of both decitabine and RN-1 could achieve additive or synergistic effects on HbF while minimizing adverse hematological side effects. Three baboons (PA8695, PA8697, PA8698) were treated with two courses of different doses of RN-1 (0.25 and 0.125mg/kg/d) administered subcutaneously for 3 days to select an optimal RN-1 dose for each animal. The response to RN-1 varied between individual animals and was associated with pretreatment levels of γ-globin expression. Higher pretreatment levels of γ-globin expression were observed in PA8697 (0.08 γ/γ+β) compared to PA8695 (0.014+0.005 γ/γ+β) and PA8698 (0.004+0.0007 γ/γ+β) and the effect on γ-globin expression in PA8697 (0.24+0.5 γ/γ+β) at the 0.125mg/kg/d dose was greater than the effect of 0.25 mg/kg/d dose in PA8695 (0.17+0.05 γ/γ+β) and PA8698 (0.121+0.006 γ/γ+β). For combinatorial studies with decitabine, an RN-1 dose of 0.125mg/kg/d was chosen for PA8697 and 0.25mg/kg/d for PA8695 and 8698. Decitabine (0.3mg/kg/d; 2d), administered as a single agent subcutaneously for two days increased F retics nearly 3 fold (23.6+12.5%; p&amp;amp;amp;lt;0.02) compared to pretreatment levels (8.26+9.90%) but changes in γ-globin expression (0.066+0.076 γ/γ+β) compared to the pretreatment levels (0.03+0.042 γ/γ+β) were not significant. For combinatorial experiments, decitabine (0.3mg/kg/d) was administered for 2 days followed by administration of RN-1 (0.25mg/kg/d PA8695 and 8698; 0.125mg/kg/d PA8697) for 3 days. This staggered dose schedule was used to avoid any possible effects of RN-1 on cell cycle kinetics that could potentially reduce incorporation of decitabine during S phase. The decitabine/RN-1 combination produced significantly higher increases in F retics (63.0+23.6%; p&amp;amp;amp;lt;0.002) than either RN-1 (29.9+27.1%) or decitabine (23.6+12.5%) alone. The effect of the decitabine/RN-1 combination on F retics was greater than additive (p&amp;amp;amp;lt;0.01; Figure 1A) in the two low HbF animals, PA8695 and 8698, and additive for the high HbF animal PA8697 (Figure 1B). Although increased levels of γ-globin expression produced by the decitabine/RN-1 combination (0.22+0.08 γ/γ+β) were not significantly different overall from those induced by RN-1 alone (0.178+0.06 γ/γ+β), individual analysis of PA8697 revealed an additive effect (Figure 1C). Plt and ANC remained with the normal range. In conclusion, targeting separate components of the γ-globin co-repressor complex by combinatorial administration of decitabine and RN-1 generated synergistic and additive increases in F retics and γ-globin expression in the absence of hematological toxicity. Future experiments will explore different doses, alternative schedules, and the effect of longer term treatment regimens. Disclosures Saunthararajah: EpiDestiny: Consultancy, Current equity holder in private company, Membership on an entity&amp;amp;#39;s Board of Directors or advisory committees, Patents &amp;amp;amp;amp; Royalties.

Blood, Dec 2, 2016

Sickle cell disease (SCD) is an inherited blood disorder that affects millions of people worldwid... more Sickle cell disease (SCD) is an inherited blood disorder that affects millions of people worldwide. A single point mutation of the sixth amino acid of β-globin causes glutamic acid to be replaced by valine, rendering the hemoglobin susceptible to polymerization when deoxygenated. SCD patients suffer from the wide variety of disease manifestations including chronic hemolytic anemia, inflammation, painful vaso-occlusive crises, multisystem organ damage, and reduced life expectancy. In addition to the HbS polymerization-mediated rigid and fragile sickle-shaped red blood cell (RBC) formation, an excessive formation of intracellular reactive oxygen species (ROS) occurs in SCD red blood cells, which accelerates their hemolysis. This causes the release of ROS, free extracellular hemoglobin, hemin, and inflammatory cytokines that trigger disease progression. We analyzed levels of ROS in SCD patient RBCs and observed a higher fraction of intracellular ROS positive RBC in SCD (HbSS) compared to control (HbAA) RBC of adults [Control (HbAA): 7.1%± 1.4 %, n=11; SCD (HbSS): 25.3 % ± 4.3%, n=9; p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.0004]. We also made the novel observation that mature RBCs from SCD patients abnormally contain mitochondria as evidenced by flow cytometry analysis of blood samples of 36 SCD patients and 14 normal human control subjects.[Control (HbAA):0.4 % ± 0.04%, n=14; SCD (HbSS): 7.8%± 0.9%, n=30; p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.0001]. Further subset analysis from SCD patients with HbSC showed mitochondrial retention in their mature RBCs [HbSC: 2.2%± 0.6%,n=6…

Pharmacogenomics, Aug 1, 2018

Blood, 2020

Sickle cell disease (SCD) is an inherited blood disorder that affects millions of people worldwid... more Sickle cell disease (SCD) is an inherited blood disorder that affects millions of people worldwide. The disease is caused by a mutation of the beta-globin gene that results in polymerization of the sickle hemoglobin (HbS) when deoxygenated. Reactive oxygen species (ROS) induced hemolysis is a major critical event in SCD. We have previously shown that abnormal retention of mitochondria in the erythrocytes of both SCD patients and SCD mice is associated with elevated ROS levels and hemolysis (Exp. Hem.2017;50:46-52). The mechanism responsible for mitochondrial retention in SCD is unknown. Autophagy is one of the processes responsible for the elimination of mitochondria during erythroid differentiation. Autophagy is a conserved physiological process that promotes cellular homeostasis through the recycling of proteins, protein aggregates, and removal of damaged organelles. Hypothesis: In this study, we have investigated the hypothesis that autophagy pathway dysregulation is responsible ...

Blood, 2018

Sickle cell disease (SCD) is an inherited red blood cell disorder that leads to vaso-occlusion, e... more Sickle cell disease (SCD) is an inherited red blood cell disorder that leads to vaso-occlusion, endothelial damage, and activation of pro-coagulant pathways. Recent studies have demonstrated that thrombotic episodes occur at a 3- to 100-fold higher rate (PMID: 17000225, 22417249) in SCD versus non-SCD populations but the risk factors for thrombosis are not clear. We investigated the incidence and predictors for thrombosis in a longitudinal cohort of 1193 SCD patients treated at our institution between 1/2008 and 12/2017. Clinical and laboratory data were extracted from the electronic medical records from the first outpatient encounter during this time period. Linear and categorical variables were compared by the Kruskal-Wallis and Chi-square test, respectively, and Cox proportional hazard models were adjusted for age, sex, SCD genotype, and hydroxyurea use. With a median follow up of 5.6 years (interquartile range [IQR], 2.3-9.3 years), 210 SCD patients (17.6%) had 347 arterial or v...

Blood, 2014

DNA methyltransferase (DNMT1) is a validated molecular target for epigenetic therapy of non-malig... more DNA methyltransferase (DNMT1) is a validated molecular target for epigenetic therapy of non-malignant diseases (e.g., sickle cell disease, SCD) and cancer. DNMT1 can be depleted by decitabine (Dec), an FDA-approved drug, without off-target cytotoxicity, reproducibly demonstrated pre-clinically. Dec, however, has pharmacologic limitations that impede translation into clinical epigenetic therapy. For e.g., DNMT-depletion requires Dec levels to overlap with cellular S-phase entry, yet the plasma half-life of Dec is <20 minutes, severely curtailing the probability of such overlap. This problem is not solved by increasing Dec dose, since off-target effects from higher Cmax causes cytotoxicity that paradoxically decreases efficacy by restricting the feasible frequency of administration. Similarly, continuous infusion is likely not the answer, since toxic increases of Dec can occur in some tissues while inadequate exposure remains in others. This unbalanced distribution could be related...

Blood, Nov 5, 2021

Increased levels of Fetal Hemoglobin (HbF) reduce the symptoms of sickle cell disease (SCD) and l... more Increased levels of Fetal Hemoglobin (HbF) reduce the symptoms of sickle cell disease (SCD) and lengthen the life span of patients. New, more effective pharmacological agents that can be safely administered long term to increase HbF levels in SCD patients are highly sought. Expression of the γ-globin gene in adult erythroid cells is normally repressed by the recruitment of multi-protein co-repressor complexes to the γ-globin promoter by sequence-specific DNA binding proteins including BCL11A, LRF1 and TR2/TR4. Enzymes contained within these co-repressor complexes, such as DNMT1, LSD1, G9A, and HDACs, modify the chromatin surrounding the γ-globin promoter by catalyzing repressive epigenetic modifications to both histones and DNA. Small molecule pharmacological inhibitors of these enzymes are potent inducers of HbF in various in cell culture and animal models and in SCD patients, but the use of these drugs in patients has been hindered by their dose-dependent effects on hematopoietic differentiation. An alternative strategy to the use of these pharmacological inhibitors to increase HbF would be to employ pharmacological activators that increase the activity of proteins that positively promote γ-globin expression. Previous studies have shown that pharmacological activators of the Sirtuin 1 protein deacetylase increased γ-globin expression in cultured human CD34+ erythroid progenitor cell cultures (Dai et al; Am J Hematol 92:1177-1186, 2017). Because Sirtuin deacetylase activity is dependent upon nicotinamide adenine dinucleotide (NAD) as a co-factor, we tested the hypothesis that increased concentrations of nicotinamide, an NAD precursor, would also increase γ-globin expression. Baboon bone marrow derived CD34+ erythroid progenitor cells from 4 individual baboons were cultured on AFT024 monolayers for 14 days in the presence and absence of varying concentrations of nicotinamide. Globin chain expression was measured in cell lysates by high performance liquid chromatography (HPLC). Nicotinamide (500μM) appeared to increase γ-globin 2 fold (0.015±0.098 γ/γ+β) compared to untreated controls (0.072±0.04 γ/γ+β; n=4; p&amp;amp;amp;lt;0.08). Because the nicotinamide levels used in this experiments are higher than can be easily achieved by dietary supplementation, additional experiments were performed to test the effect of P7C3-A20, an allosteric activator of nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in the NAD synthesis, on γ-globin expression. Addition of P7C3-A20 (2.5μM) to CD34+ erythroid progenitor cultures on d1, 4, 7, and 10 increased γ-globin 2.7 fold (0.247±0.10 γ/γ+β) compared to vehicle-treated controls (0.090±0.06 γ/γ+β; n=5; p&amp;amp;amp;lt;0.01). P7C3-A20 treatment did not affect cell viability or growth at concentration&amp;amp;amp;lt; 2.5μM and dose-response experiments showed increased γ-globin in cultures treated with submicromolar concentrations of the drug. Addition of P7C3-A20 to cultures on days 1 and 4 resulted in near maximal stimulation of γ-globin expression with lesser effects when the drug was added on later days (d4 and7 or d7 and 10) strongly suggesting that the drug targets cells at an early stage of differentiation. Additional experiments showed that the effect of P7C3-A20 (2.5μM) in combination with either the DNMT1 inhibitor decitabine (DAC) or the LSD1 inhibitor tranylcypromine (TCP) resulted in a greater than additive effects on γ-globin expression in the absence of cytotoxicity (Figure 1). In conclusion, the NAMPT activator P7C3-A20 increased γ-globin expression in baboon CD34+ erythroid progenitor cells with greater than additive effects in combination with DAC or TCP. P7C3-A20 has potent in vivo effects as a neuroprotective drug in mouse models and non-human primates. Therefore, the potential of this drug for in vivo HbF induction warrants further investigation. Figure 1 Figure 1. Disclosures Saunthararajah: EpiDestiny: Consultancy, Current holder of individual stocks in a privately-held company, Membership on an entity&amp;amp;#39;s Board of Directors or advisory committees, Patents &amp;amp;amp;amp; Royalties.

Blood, Dec 2, 2016

Increased levels of fetal hemoglobin (HbF) lessen the severity of symptoms and increase the life ... more Increased levels of fetal hemoglobin (HbF) lessen the severity of symptoms and increase the life span of patients with sickle cell disease. New and more effective strategies to increase HbF are needed because current therapies are ineffective in a significant proportion of patients. The lysine-specific demethylase, LSD1, an enzyme that demethylates Histone H3 mono- and dimethyl- K4 and K9 residues, is a component of the DRED co-repressor complex that represses the γ-globin gene (Cui et al, Mol Cell Biol 31:3298, 2011). Our laboratory has recently shown that RN-1, a pharmacological inhibitor of LSD1, increases γ-globin expression in sickle cell disease (SCD) transgenic mice (Rivers et al, Exp Hematol 43:546, 2015; Cui et al, Blood 126:386, 2015) and in baboons (Rivers et al, Haematol 101:688, 2016), widely acknowledge as the best animal model to test the activity of HbF-inducing drugs. To evaluate the safety and efficacy of RN-1, two normal, non-anemic baboons were treated for an extended period with RN-1 (PA8695, 264d; PA8698, 278d; 0.25mg/kg/d; 5d/wk, sc) and the effect on HbF, F cells, and hematological parameters evaluated weekly. Both animals exhibited weight gain (PA8695: 14.4%; PA8698: 20%) during the course of the study. F retics were increased 8-10 fold by the second week (d9) and were maintained at high levels throughout the course of the study (PA8695: 55.7±17.7% (mean±SD), median (M)=59.0%; PA8698: 56.4±14.5%, M=56.9%). F cell levels increased until d169 and were maintained thereafter at levels 18-25 times greater than pre-treatment (PA8695: 54.5±3.3%, M=54.2%; PA8698: 51.7±3.2%, M=51.4%). HbF levels also increased until d169 and were also maintained thereafter at levels 10-12 times greater than pre-treatment (PA8695: 12.8±1.7%, M=12.1%; PA8698: 11.4±1.4%, M=11.5%). Elevated levels of γ-globin chain synthesis were observed in the peripheral blood on multiple days (d162, d190, d267) of treatment (PA8695, 0.28±0.08 γ/γ+β;PA8698, 0.26±0.08 γ/γ+β). RT-PCR analysis showed that γ-globin mRNA levels were increased 9-22 fold (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.01) in FACS-purified CD105+ CD117+/- glyA+ BM erythroid precursor subpopulations of RN-1 treated baboons compared to normal baboons. Absolute neutrophil counts showed no overall decline compared to pre-treatment (PA8695: pre-treatment=2110/μL, post-treatment=3118±1452/μL, M=2765/μL; PA8698: pre-treatment=2690/μL, post-treatment=2936±696/μL, M=2460/μL) although variations were observed. In PA8695 the ANC declined below 1500/μL twice (1490, 1160) and five times (1250, 1410, 1420, 1330, 1000) in PA8595. Monocytes increased 2-3 fold in each animal (PA8695: pre-treatment=100/μL, post-treatment=252±97/μL, M=246/μL; PA8698: pre-treatment=161/μL, post-treatment=425±319/μL, M=347/μL). Hemoglobin (Hb), RBC, and hematocrit (HCT) levels exhibited small overall decreases during the course of treatment but remained within the normal range. Decreases in RBC, Hb, and HCT were associated with blood loss during menstruation (PA8695) and following an accidental laceration of the perineal swelling (PA8698). Rapid recovery was observed in both animals. Significant changes in MCV, MCH, and MCHC during treatment were not observed. Platelet levels decreased approximately 40% in each animal but nevertheless were maintained within the normal range (PA8695: pre-treatment=351 X 103/μL, post-treatment=236±64 X 103/μL, M=219 X 103/μL; PA8698: pre-treatment=224 X 103/μL, post-treatment=143±78 X 103/μL, M=119 X 103/μL). No significant differences in either PT or aPTT assays were observed compared to normal baboons. In vitro platelet activation assays performed to investigate effects on platelet function showed that the fraction of platelets expressing P-selectin (CD62P) on the surface following…

Seminars in Hematology, 2021

Human hemoglobin switching describes the highly regulated, sequential expression of the five β-li... more Human hemoglobin switching describes the highly regulated, sequential expression of the five β-like globin genes (HBE, HBG2, HBG1, HBD and HBB) of the human β-globin gene complex. The sequential activation of these β or β-like globin genes during human development from early embryonic through late fetal (‘adult’) stages, and during erythroid maturation, occurs in an order corresponding to their 5’ to 3’ location on chromosome 11. The β-hemoglobinopathies are the most common inherited diseases in humanity, and are diseases of mutated HBB or its altered regulation. Since the other β-like globin genes can potentially substitute for defective HBB, much translational research is directed toward understanding and manipulating sequential activation at the human β-globin gene complex to treat β-hemoglobinopathies. Non-human primates provide a vital contribution to such efforts because of their recapitulation of the developmental/maturational switch in hemoglobin production as observed in humans (mice do not model this switch). Valuable insights into druggable epigenetic forces that mediate the switch have been thereby gained. We review important lessons learned in non-human primates, complemented by other studies, and suggest rational next steps.

Current developments in nutrition, Jun 1, 2019

Haematologica, Dec 1, 2019

Blood, Nov 5, 2020

Pharmacological treatments designed to increase Fetal Hemoglobin (HbF) levels offer great promise... more Pharmacological treatments designed to increase Fetal Hemoglobin (HbF) levels offer great promise to alleviate the symptoms and improve the lifespan of the vast numbers of patients afflicted with sickle cell disease (SCD) and β-thalassemia. Hydroxyurea can increase HbF, but a large fraction of patients with SCD do not respond to the drug. DNMT1 and LSD1 inhibitors are the most powerful drugs to increase HbF but are limited by side effects that include neutropenia, thrombophilia and/or thrombocytopenia. The development of new, more effective, and safer pharmacological strategies to augment HbF levels in the blood thus continues to be an important goal. Previous studies have shown that γ-globin gene expression is dynamically regulated during erythroid differentiation (Papayannopoulou et al PNAS 74:2923-2927, 1977). The proportion of γ-globin gene expression is higher at earlier stages (BFUe) of erythroid differentiation than at more advanced stages (CFUe). Therefore, we suggest the hypothesis that expansion of primitive, less differentiated progenitors might favor increased γ-globin, particularly when combined other HbF-inducing drugs. To investigate this hypothesis, we have tested whether nicotinamide (NAM), the major NAM metabolite 1-methylnicotinamide (1-mNAM), and N&#39;-methylnicotinamide (N&#39;-mNAM), a chemical derivative of NAM, can foster expansion of erythroid colony-forming cells (BFUe and CFUe) and increase γ-globin expression of cultured baboon CD34+ cells. Previous observations have shown that NAM facilitates in vitro expansion of cord blood CD34+ cells and enhanced long term engraftment in transplanted recipients (Horwitz et al J Clin Invest 124:3121, 2014). Contrasting effects of NAM, 1-mNAM, and N&#39;-mNAM on differentiation and proliferation of the murine erythroleukemia cell line (MEL) have been previously reported (Terada et al PNAS 76:6414, 1979; Kuykendall et al Toxicol In Vitro 21:1656, 2007). While both NAM and N&#39;-mNAM induced MEL cell differentiation, N&#39;-mNAM was far more potent. In contrast, 1-mNAM increased cell proliferation, reduced spontaneous differentiation, and blocked differentiation induced by NAM and N&#39;-mNAM. The effect of all three forms of NAM was examined using bone marrow (BM) CD34+ cells from a pre-clinical non-human primate large animal model. To test the effect of NAM, 1-mNAM, and N&#39;-mNAM on expansion of erythroid colony-forming cells, the agents (5mM) were added to liquid cultures of baboon CD34+ bone marrow cells previously expanded for 5 days in serum-free expansion media (SFEM). Colony assays were performed on d8. In two experiments total erythroid colonies (BFUe and CFUe) were 2 fold higher in cultures treated with 1-mNAM compared to untreated controls (p&amp;lt;0.05) while no effect was observed in cultures treated with NAM. No colonies were observed in cultures treated with N&#39;-mNAM (Figure 1A). Observation of Wright&#39;s stained cytospin preparations showed extensive erythroid differentiation on d8 in cells treated with N&#39;-mNAM (Figure 1B). The effect of NAM, 1-mNAM, and N&#39;-NAM on γ-globin expression was tested in baboon CD34+ cells grown in co-culture with the AFT024 cell line. NAM, 1-mNAM, or N&#39;-mNAM (5mM) were added to cultures on d7. Expression of γ- and β-globin mRNA was measured by RT-PCR on d17. Increased γ-globin expression (0.57±0.04 γ/γ+β)) was observed in cells treated with N&#39;-mNAM on d7 compared to untreated controls (0.20±0.09 γ/γ+β; p&amp;lt;0.001). NAM and 1-mNAM had no significant effect on γ-globin gene expression (Figure 1C). These results thus show that while erythroid colonies are increased by 1-mNAM, N&#39;-mNAM is a potent inducer of erythroid differentiation and increases γ-globin expression in primary cultures of baboon CD34+ cells. In conclusion, 1-mNAM and N&#39;-mNAM have contrasting effects on erythroid differentiation in primary baboon CD34+ cell cultures, confirming previous experiments in the MEL cell line. Future experiments are planned to test the effect of these agents on HbF in the baboon. Disclosures Saunthararajah: EpiDestiny: Consultancy, Current equity holder in private company, Membership on an entity&#39;s Board of Directors or advisory committees, Patents &amp;amp; Royalties.

Blood, Dec 6, 2014

Increased levels of fetal hemoglobin (HbF) lessen the severity of symptoms and increase the life ... more Increased levels of fetal hemoglobin (HbF) lessen the severity of symptoms and increase the life span of patients with sickle cell disease (SCD). Differences in DNA methylation of the γ-globin gene promoter between adult and fetal liver erythroid cells are highly associated with developmental differences in γ-globin expression. Mechanisms that establish and/or modulate DNA methylation of the γ-globin promoter during adult and fetal erythroid differentiation are important in the regulation of γ-globin expression. Pharmacological manipulation of DNA methylation increases HbF in nonhuman primates and SCD patients. Decitabine, a DNA methyltransferase inhibitor that demethylates DNA and increases HbF, is currently in clinical trials. Recent studies have shown that 5-hydroxymethylcytosine (5-hmC), an oxidative product of 5-methylcytosine (5-mC) catalyzed by activity of the TET dioxygenase family, is an intermediate in developmental processes that demethylate DNA. Previously we showed that the γ-globin gene promoter was demethylated during fetal liver erythroid differentiation and to a lesser extent during adult bone marrow (BM) erythroid differentiation. We have investigated the role of 5-hmC in the mechanism of γ-globin gene demethylation by analyzing 5-hmC levels at the HpaII site located at position -51 5’ to the γ-globin transcription start site using a T4-MspI assay in DNA isolated from FACS-purified subpopulations of baboon BM cells enriched for different stages of erythroid lineage differentiation. Levels of 5-hmC were &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;3 fold higher (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001) in the CD117+CD36+ subpopulation enriched in CFUe (7.15+1.34%) compared to the terminal erythroid precursors (2.33+0.84%) showing that 5-hmC levels are dynamically regulated during erythroid differentiation. Although baboon BM erythroid subpopulations express both TET2 and TET3, higher levels of TET3 were observed in terminal erythroid precursors than in the more primitive CD117+CD36+ subpopulation. High levels of TET3 were also observed in FACS-purified erythroid cells derived from cultured CD34+ baboon BM, human peripheral blood, and human cord blood cells suggesting a role for TET3 in erythroid differentiation. To investigate the relationship between 5-hmC, 5-mC, and γ-globin expression, levels of γ-globin promoter 5-hmC and 5-mC were determined in purified erythroid cells derived from baboon BM CD34+ erythroid progenitors grown in culture…

Blood, Nov 5, 2021

The polymerization of deoxygenated HbS molecules in the red blood cells (RBCs) of patients with s... more The polymerization of deoxygenated HbS molecules in the red blood cells (RBCs) of patients with sickle cell disease (SCD) causes RBC destruction resulting in chronic pain, debilitating acute pain crises, strokes, multi-organ damage and a reduced life span. Therapeutic options remain limited. Bone marrow transplantation can be curative but is not an option for the majority of patients. Gene therapy interventions that also offer the promise of a cure are under investigation but are not likely to be available to the vast majority of patients in the near future. Hydroxyurea, the first drug approved for treatment of SCD, increases levels of Fetal Hemoglobin (HbF) that inhibit polymerization of HbS molecules but is not effective in all patients while a more powerful HbF-inducing drug, the DNA methyltransferase inhibitor decitabine has yet to be approved. L-glutamine, another approved therapeutic option, increases NAD redox potential and decreases reactive oxygen species (ROS) in the sickle RBCs to reduce symptoms. In our laboratory we have observed that increased ROS is associated with the retention of mitochondria in the SCD RBCs and have hypothesized that the abnormal presence of mitochondria in these cells is a major source of ROS (Jagadeeswaran et al Exp Hematol 50:46-52, 2017). In this investigation we have tested the hypothesis that chronic oral supplementation with nicotinamide, a direct precursor of NAD synthesis, would improve NAD redox potential, decrease mitochondrial retention and ROS in SCD RBCs, and reduce anemia in the SCD mouse model. The effect of nicotinamide was tested in SCD mice whose drinking water was supplemented for three months with 1% nicotinamide. The percentage of RBCs retaining mitochondria and the levels of ROS were determined by flow cytometric assays using the mitochondrial-specific dye TMRM and the ROS probe CM-H2DCFDA, respectively. In SCD mice receiving nicotinamide the fraction of RBCs retaining mitochondria was reduced 22.1% (p<0.05) and the level of ROS in RBCs was reduced 41% (p<0.01) compared to control SCD mice. The reticulocyte percentage was reduced 28% in nicotinamide-treated SCD mice compared to control SCD mice (p<0.01). The total RBC count was 30% higher (p<0.05) in nicotinamide-treated mice (6.61±0.76 X 10 6/μl) compared to control SCD mice (5.08±0.70 X 10 6/μl). Similar differences in hematocrit and total hemoglobin were also observed but failed to reach statistical significance. Total NAD levels were not significantly different in SCD mice receiving nicotinamide compared to control SCD mice (p<0.05), but the NADH/NAD total ratio was increased 2 fold (p<0.05). These results show that oral administration of high doses of nicotinamide decreases mitochondrial retention and ROS in SCD RBCs and improves NAD redox potential and anemia in SCD mice. These effects strongly suggest that additional studies be performed to investigate nicotinamide as a therapeutic option in SCD. Figure 1 Figure 1. Saunthararajah: EpiDestiny: Consultancy, Current holder of individual stocks in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties.

Experimental Hematology, Jun 1, 2023

Blood Advances, May 8, 2020

Blood, Nov 5, 2020

Sickle cell disease (SCD) is an inherited blood disorder that severely impacts the quality of lif... more Sickle cell disease (SCD) is an inherited blood disorder that severely impacts the quality of life and reduces the life expectancy of approximately 100,000 patients in the U.S. and millions worldwide. Elevated levels of Fetal Hemoglobin (HbF; α2γ2) reduce the severity of symptoms and lengthen the life span of patients with sickle cell disease by inhibiting deoxy HbS polymerization. Hydroxyurea (HU), the only FDA-approved drug shown to increase HbF, is not effective in a subset of patientsand importantly, in the refractory individuals the increased HbFis heterogeneously distributed within the erythrocyte population resulting in a large fraction of erythrocytes lacking protective levels. Simian primates such as the baboon are widely acknowledged as the best animal models for testing the ability of new drugs to increase γ-globin expression because results in baboons are predictive of effects in man due to conservation of the structure and developmental stage-specific regulation of the β-like globin genes in simian primates. Our previous studies in baboons have shown that the most powerful drugs for reactivation of HbF are DNMT1 and KDM1A inhibitors targeting enzymes located within the co-repressor complexes that act to establish and maintain repressive epigenetic modifications at the γ-globin promoter to repress γ-globin expression. Treatment of baboons with either decitabine, an inhibitor of DNMT1, or RN-1, an inhibitor of KDM1A, strongly stimulates HbF. Dose-limiting effects of these drugs include neutropenia, thrombocytopenia, and/or thrombophilia. In this investigation we have explored the hypothesis that a treatment regimen comprised of both decitabine and RN-1 could achieve additive or synergistic effects on HbF while minimizing adverse hematological side effects. Three baboons (PA8695, PA8697, PA8698) were treated with two courses of different doses of RN-1 (0.25 and 0.125mg/kg/d) administered subcutaneously for 3 days to select an optimal RN-1 dose for each animal. The response to RN-1 varied between individual animals and was associated with pretreatment levels of γ-globin expression. Higher pretreatment levels of γ-globin expression were observed in PA8697 (0.08 γ/γ+β) compared to PA8695 (0.014+0.005 γ/γ+β) and PA8698 (0.004+0.0007 γ/γ+β) and the effect on γ-globin expression in PA8697 (0.24+0.5 γ/γ+β) at the 0.125mg/kg/d dose was greater than the effect of 0.25 mg/kg/d dose in PA8695 (0.17+0.05 γ/γ+β) and PA8698 (0.121+0.006 γ/γ+β). For combinatorial studies with decitabine, an RN-1 dose of 0.125mg/kg/d was chosen for PA8697 and 0.25mg/kg/d for PA8695 and 8698. Decitabine (0.3mg/kg/d; 2d), administered as a single agent subcutaneously for two days increased F retics nearly 3 fold (23.6+12.5%; p&amp;amp;amp;lt;0.02) compared to pretreatment levels (8.26+9.90%) but changes in γ-globin expression (0.066+0.076 γ/γ+β) compared to the pretreatment levels (0.03+0.042 γ/γ+β) were not significant. For combinatorial experiments, decitabine (0.3mg/kg/d) was administered for 2 days followed by administration of RN-1 (0.25mg/kg/d PA8695 and 8698; 0.125mg/kg/d PA8697) for 3 days. This staggered dose schedule was used to avoid any possible effects of RN-1 on cell cycle kinetics that could potentially reduce incorporation of decitabine during S phase. The decitabine/RN-1 combination produced significantly higher increases in F retics (63.0+23.6%; p&amp;amp;amp;lt;0.002) than either RN-1 (29.9+27.1%) or decitabine (23.6+12.5%) alone. The effect of the decitabine/RN-1 combination on F retics was greater than additive (p&amp;amp;amp;lt;0.01; Figure 1A) in the two low HbF animals, PA8695 and 8698, and additive for the high HbF animal PA8697 (Figure 1B). Although increased levels of γ-globin expression produced by the decitabine/RN-1 combination (0.22+0.08 γ/γ+β) were not significantly different overall from those induced by RN-1 alone (0.178+0.06 γ/γ+β), individual analysis of PA8697 revealed an additive effect (Figure 1C). Plt and ANC remained with the normal range. In conclusion, targeting separate components of the γ-globin co-repressor complex by combinatorial administration of decitabine and RN-1 generated synergistic and additive increases in F retics and γ-globin expression in the absence of hematological toxicity. Future experiments will explore different doses, alternative schedules, and the effect of longer term treatment regimens. Disclosures Saunthararajah: EpiDestiny: Consultancy, Current equity holder in private company, Membership on an entity&amp;amp;#39;s Board of Directors or advisory committees, Patents &amp;amp;amp;amp; Royalties.

Blood, Dec 2, 2016

Sickle cell disease (SCD) is an inherited blood disorder that affects millions of people worldwid... more Sickle cell disease (SCD) is an inherited blood disorder that affects millions of people worldwide. A single point mutation of the sixth amino acid of β-globin causes glutamic acid to be replaced by valine, rendering the hemoglobin susceptible to polymerization when deoxygenated. SCD patients suffer from the wide variety of disease manifestations including chronic hemolytic anemia, inflammation, painful vaso-occlusive crises, multisystem organ damage, and reduced life expectancy. In addition to the HbS polymerization-mediated rigid and fragile sickle-shaped red blood cell (RBC) formation, an excessive formation of intracellular reactive oxygen species (ROS) occurs in SCD red blood cells, which accelerates their hemolysis. This causes the release of ROS, free extracellular hemoglobin, hemin, and inflammatory cytokines that trigger disease progression. We analyzed levels of ROS in SCD patient RBCs and observed a higher fraction of intracellular ROS positive RBC in SCD (HbSS) compared to control (HbAA) RBC of adults [Control (HbAA): 7.1%± 1.4 %, n=11; SCD (HbSS): 25.3 % ± 4.3%, n=9; p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.0004]. We also made the novel observation that mature RBCs from SCD patients abnormally contain mitochondria as evidenced by flow cytometry analysis of blood samples of 36 SCD patients and 14 normal human control subjects.[Control (HbAA):0.4 % ± 0.04%, n=14; SCD (HbSS): 7.8%± 0.9%, n=30; p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.0001]. Further subset analysis from SCD patients with HbSC showed mitochondrial retention in their mature RBCs [HbSC: 2.2%± 0.6%,n=6…

Pharmacogenomics, Aug 1, 2018

Blood, 2020

Sickle cell disease (SCD) is an inherited blood disorder that affects millions of people worldwid... more Sickle cell disease (SCD) is an inherited blood disorder that affects millions of people worldwide. The disease is caused by a mutation of the beta-globin gene that results in polymerization of the sickle hemoglobin (HbS) when deoxygenated. Reactive oxygen species (ROS) induced hemolysis is a major critical event in SCD. We have previously shown that abnormal retention of mitochondria in the erythrocytes of both SCD patients and SCD mice is associated with elevated ROS levels and hemolysis (Exp. Hem.2017;50:46-52). The mechanism responsible for mitochondrial retention in SCD is unknown. Autophagy is one of the processes responsible for the elimination of mitochondria during erythroid differentiation. Autophagy is a conserved physiological process that promotes cellular homeostasis through the recycling of proteins, protein aggregates, and removal of damaged organelles. Hypothesis: In this study, we have investigated the hypothesis that autophagy pathway dysregulation is responsible ...

Blood, 2018

Sickle cell disease (SCD) is an inherited red blood cell disorder that leads to vaso-occlusion, e... more Sickle cell disease (SCD) is an inherited red blood cell disorder that leads to vaso-occlusion, endothelial damage, and activation of pro-coagulant pathways. Recent studies have demonstrated that thrombotic episodes occur at a 3- to 100-fold higher rate (PMID: 17000225, 22417249) in SCD versus non-SCD populations but the risk factors for thrombosis are not clear. We investigated the incidence and predictors for thrombosis in a longitudinal cohort of 1193 SCD patients treated at our institution between 1/2008 and 12/2017. Clinical and laboratory data were extracted from the electronic medical records from the first outpatient encounter during this time period. Linear and categorical variables were compared by the Kruskal-Wallis and Chi-square test, respectively, and Cox proportional hazard models were adjusted for age, sex, SCD genotype, and hydroxyurea use. With a median follow up of 5.6 years (interquartile range [IQR], 2.3-9.3 years), 210 SCD patients (17.6%) had 347 arterial or v...

Blood, 2014

DNA methyltransferase (DNMT1) is a validated molecular target for epigenetic therapy of non-malig... more DNA methyltransferase (DNMT1) is a validated molecular target for epigenetic therapy of non-malignant diseases (e.g., sickle cell disease, SCD) and cancer. DNMT1 can be depleted by decitabine (Dec), an FDA-approved drug, without off-target cytotoxicity, reproducibly demonstrated pre-clinically. Dec, however, has pharmacologic limitations that impede translation into clinical epigenetic therapy. For e.g., DNMT-depletion requires Dec levels to overlap with cellular S-phase entry, yet the plasma half-life of Dec is <20 minutes, severely curtailing the probability of such overlap. This problem is not solved by increasing Dec dose, since off-target effects from higher Cmax causes cytotoxicity that paradoxically decreases efficacy by restricting the feasible frequency of administration. Similarly, continuous infusion is likely not the answer, since toxic increases of Dec can occur in some tissues while inadequate exposure remains in others. This unbalanced distribution could be related...