The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Alberto Rissone - One of the best experts on this subject based on the ideXlab platform.
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a model for reticular dysgenesis shows impaired sensory organ development and hair cell regeneration linked to cellular stress
Disease Models & Mechanisms, 2019Co-Authors: Alberto Rissone, Kevin Bishop, Raman Sood, Fabio Candotti, Erin Jimenez, Blake Carrington, Claire Slevin, Stephen Wincovitch, Shawn M BurgessAbstract:ABSTRACT Mutations in the gene AK2 are responsible for reticular dysgenesis (RD), a rare and severe form of primary immunodeficiency in children. RD patients have a severely shortened life expectancy and without treatment die, generally from sepsis soon after birth. The only available therapeutic option for RD is hematopoietic stem cell transplantation (HSCT). To gain insight into the pathophysiology of RD, we previously created zebrafish models for AK2 deficiencies. One of the clinical features of RD is hearing loss, but its pathophysiology and causes have not been determined. In adult mammals, sensory hair cells of the inner ear do not regenerate; however, their regeneration has been observed in several non-mammalian vertebrates, including zebrafish. Therefore, we used our RD zebrafish models to determine whether AK2 deficiency affects sensory organ development and/or hair cell regeneration. Our studies indicated that AK2 is required for the correct development, survival and regeneration of sensory hair cells. Interestingly, AK2 deficiency induces the expression of several oxidative stress markers and it triggers an increased level of cell death in the hair cells. Finally, we show that glutathione treatment can partially rescue hair cell development in the sensory organs in our RD models, pointing to the potential use of antioxidants as a therapeutic treatment supplementing HSCT to prevent or ameliorate sensorineural hearing deficits in RD patients.
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a model for reticular dysgenesis shows impaired sensory organ development and hair cell regeneration linked to cellular stress
bioRxiv, 2019Co-Authors: Alberto Rissone, Kevin Bishop, Raman Sood, Fabio Candotti, Erin Jimenez, Blake Carrington, Claire Slevin, Stephen Wincovitch, Shawn M BurgessAbstract:Mutations in the gene AK2 are responsible for Reticular Dysgenesis (RD), a rare and severe form of primary immunodeficiency in children. RD patients have a severely shortened life expectancy and without treatment die a few weeks after birth. The only available therapeutic option for RD is bone marrow transplantation. To gain insight into the pathophysiology of RD, we previously created zebrafish models for an AK2 deficiency. One of the clinical features of RD is hearing loss, but its pathology and causes have not been determined. In adult mammals, sensory hair cells of the inner ear do not regenerate; however, their regeneration has been observed in several non-mammalian vertebrates, including zebrafish. Therefore, we use our RD zebrafish models to determine if AK2 deficiency affects sensory organ development and/or hair cell regeneration. Our studies indicated that AK2 is required for the correct development, survival and regeneration of sensory hair cells. Interestingly, AK2 deficiency induces the expression of several oxidative stress markers and it triggers an increased level of cell death in the hair cells. Finally, we show that glutathione treatment can partially rescue hair cell development in the sensory organs in our RD models, pointing to the potential use of antioxidants as a supportive therapeutic modality for RD patients, not only to increase their chances of survival, but to prevent or ameliorate their sensorineural hearing deficits.
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reticular dysgenesis associated AK2 protects hematopoietic stem and progenitor cell development from oxidative stress
Journal of Experimental Medicine, 2015Co-Authors: Alberto Rissone, Katja G Weinacht, Kevin Bishop, Giancarlo La Marca, Elisa Giocaliere, Jayashree Jagadeesh, Kerstin Felgentreff, Kerry Dobbs, Waleed AlherzAbstract:Adenylate kinases (AKs) are phosphotransferases that regulate the cellular adenine nucleotide composition and play a critical role in the energy homeostasis of all tissues. The AK2 isoenzyme is expressed in the mitochondrial intermembrane space and is mutated in reticular dysgenesis (RD), a rare form of severe combined immunodeficiency (SCID) in humans. RD is characterized by a maturation arrest in the myeloid and lymphoid lineages, leading to early onset, recurrent, and overwhelming infections. To gain insight into the pathophysiology of RD, we studied the effects of AK2 deficiency using the zebrafish model and induced pluripotent stem cells (iPSCs) derived from fibroblasts of an RD patient. In zebrafish, AK2 deficiency affected hematopoietic stem and progenitor cell (HSPC) development with increased oxidative stress and apoptosis. AK2-deficient iPSCs recapitulated the characteristic myeloid maturation arrest at the promyelocyte stage and demonstrated an increased AMP/ADP ratio, indicative of an energy-depleted adenine nucleotide profile. Antioxidant treatment rescued the hematopoietic phenotypes in vivo in AK2 mutant zebrafish and restored differentiation of AK2-deficient iPSCs into mature granulocytes. Our results link hematopoietic cell fate in AK2 deficiency to cellular energy depletion and increased oxidative stress. This points to the potential use of antioxidants as a supportive therapeutic modality for patients with RD.
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Reticular dysgenesis–associated AK2 protects hematopoietic stem and progenitor cell development from oxidative stress
Journal of Experimental Medicine, 2015Co-Authors: Alberto Rissone, Katja G Weinacht, Kevin Bishop, Waleed Al-herz, Giancarlo La Marca, Elisa Giocaliere, Jayashree Jagadeesh, Kerstin Felgentreff, Kerry Dobbs, Marypat JonesAbstract:Adenylate kinases (AKs) are phosphotransferases that regulate the cellular adenine nucleotide composition and play a critical role in the energy homeostasis of all tissues. The AK2 isoenzyme is expressed in the mitochondrial intermembrane space and is mutated in reticular dysgenesis (RD), a rare form of severe combined immunodeficiency (SCID) in humans. RD is characterized by a maturation arrest in the myeloid and lymphoid lineages, leading to early onset, recurrent, and overwhelming infections. To gain insight into the pathophysiology of RD, we studied the effects of AK2 deficiency using the zebrafish model and induced pluripotent stem cells (iPSCs) derived from fibroblasts of an RD patient. In zebrafish, AK2 deficiency affected hematopoietic stem and progenitor cell (HSPC) development with increased oxidative stress and apoptosis. AK2-deficient iPSCs recapitulated the characteristic myeloid maturation arrest at the promyelocyte stage and demonstrated an increased AMP/ADP ratio, indicative of an energy-depleted adenine nucleotide profile. Antioxidant treatment rescued the hematopoietic phenotypes in vivo in AK2 mutant zebrafish and restored differentiation of AK2-deficient iPSCs into mature granulocytes. Our results link hematopoietic cell fate in AK2 deficiency to cellular energy depletion and increased oxidative stress. This points to the potential use of antioxidants as a supportive therapeutic modality for patients with RD.
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Adenylate Kinase 2 Regulates Zebrafish Primitive and Definitive Hematopoiesis
Blood, 2012Co-Authors: Alberto Rissone, Kevin Bishop, Trevor Blake, Raman Sood, Jaya Jagadeesh, Simon Karen, Fabio CandottiAbstract:Abstract 1208 Introduction: The adenylate kinase (AK) gene family consists of 7 different members that contribute to energy cell metabolism by converting ATP + AMP to 2 molecules of ADP. AKs are critical players in ensuring cellular energy homeostasis in all tissues and are generally involved in a broad range of cellular functions. Among AKs, AK2 has unique features such as its location in the mitochondrial intermembrane space and critical role in human lymphopoiesis and granulopoiesis. Indeed, mutations of the AK2 gene cause reticular dysgenesis (RD), an autosomal recessive form of severe combined immunodeficiency (SCID) characterized by an early differentiation arrest in the granulocyte lineage and impaired lymphoid maturation. The mechanisms underlying the pathophysiology of RD remain unclear. The phenotype of AK2 deficient animals has not been reported in the literature, but murine lines carrying homozygous inactivating retroviral insertions are embryonically lethal (our personal observations). Objectives: To study the role of AK2 in hematopoietic system development and define the effects of AK2 deficiency, we set out to generate a zebrafish model of RD. Methods: We injected zebrafish embryos with morpholino oligomers specific for the two zebrafish AK2 isoforms and analyzed the serial expression pattern of several hematopoietic markers in developing AK2 morphants. To confirm our observations in AK2 knockdown embryos, we screened a zebrafish DNA library of ENU-induced mutations and recovered a mutant fish line carrying a T371C/L124P missense mutation within the exon 4 of AK2 gene that is predicted to be deleterious for protein stability and function. Results: The downregulation of zebrafish AK2 expression phenocopied the human disease and resulted in strong reduction of developing lymphocytes. In addition, in situ hybridization for GATA1, alpha-globin 1, L-plastin and Odianisidine staining indicated that erythroid development was affected in AK2 morphants during primitive hematopoiesis, while myeloid development was conserved. Furthermore, in situ hybridization studies of the expression of markers of zebrafish definitive hematopoiesis showed abnormalities distributed among all hematopoietic lineages suggesting a broad role of AK2 in zebrafish hematopoiesis. Importantly, the ENU-induced AK2 mutant recapitulated all the primitive and definitive hematopoietic phenotypes observed in AK2 morphants. Finally, preliminary data suggest that AK2 deficiency (both in morphant and mutant embryos) induces an increased level of reactive oxygen species (ROS) triggering oxidative stress and consequent apoptosis in hematopoietic progenitor cells. Conclusions: Our data provide new insights into the AK2 function and indicate that zebrafish represents a good model for studying the molecular mechanisms involved in RD. To date, our mutant line represents the first example of animal model of this rare and unique human disease. Disclosures: No relevant conflicts of interest to declare.
Fabio Candotti - One of the best experts on this subject based on the ideXlab platform.
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a model for reticular dysgenesis shows impaired sensory organ development and hair cell regeneration linked to cellular stress
Disease Models & Mechanisms, 2019Co-Authors: Alberto Rissone, Kevin Bishop, Raman Sood, Fabio Candotti, Erin Jimenez, Blake Carrington, Claire Slevin, Stephen Wincovitch, Shawn M BurgessAbstract:ABSTRACT Mutations in the gene AK2 are responsible for reticular dysgenesis (RD), a rare and severe form of primary immunodeficiency in children. RD patients have a severely shortened life expectancy and without treatment die, generally from sepsis soon after birth. The only available therapeutic option for RD is hematopoietic stem cell transplantation (HSCT). To gain insight into the pathophysiology of RD, we previously created zebrafish models for AK2 deficiencies. One of the clinical features of RD is hearing loss, but its pathophysiology and causes have not been determined. In adult mammals, sensory hair cells of the inner ear do not regenerate; however, their regeneration has been observed in several non-mammalian vertebrates, including zebrafish. Therefore, we used our RD zebrafish models to determine whether AK2 deficiency affects sensory organ development and/or hair cell regeneration. Our studies indicated that AK2 is required for the correct development, survival and regeneration of sensory hair cells. Interestingly, AK2 deficiency induces the expression of several oxidative stress markers and it triggers an increased level of cell death in the hair cells. Finally, we show that glutathione treatment can partially rescue hair cell development in the sensory organs in our RD models, pointing to the potential use of antioxidants as a therapeutic treatment supplementing HSCT to prevent or ameliorate sensorineural hearing deficits in RD patients.
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a model for reticular dysgenesis shows impaired sensory organ development and hair cell regeneration linked to cellular stress
bioRxiv, 2019Co-Authors: Alberto Rissone, Kevin Bishop, Raman Sood, Fabio Candotti, Erin Jimenez, Blake Carrington, Claire Slevin, Stephen Wincovitch, Shawn M BurgessAbstract:Mutations in the gene AK2 are responsible for Reticular Dysgenesis (RD), a rare and severe form of primary immunodeficiency in children. RD patients have a severely shortened life expectancy and without treatment die a few weeks after birth. The only available therapeutic option for RD is bone marrow transplantation. To gain insight into the pathophysiology of RD, we previously created zebrafish models for an AK2 deficiency. One of the clinical features of RD is hearing loss, but its pathology and causes have not been determined. In adult mammals, sensory hair cells of the inner ear do not regenerate; however, their regeneration has been observed in several non-mammalian vertebrates, including zebrafish. Therefore, we use our RD zebrafish models to determine if AK2 deficiency affects sensory organ development and/or hair cell regeneration. Our studies indicated that AK2 is required for the correct development, survival and regeneration of sensory hair cells. Interestingly, AK2 deficiency induces the expression of several oxidative stress markers and it triggers an increased level of cell death in the hair cells. Finally, we show that glutathione treatment can partially rescue hair cell development in the sensory organs in our RD models, pointing to the potential use of antioxidants as a supportive therapeutic modality for RD patients, not only to increase their chances of survival, but to prevent or ameliorate their sensorineural hearing deficits.
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AK2 deficiency in zebrafish recapitulates human reticular dysgenesis an autosomal recessive form of severe combined immunodeficiency
Blood, 2013Co-Authors: Jaya Jagadeesh, Karen L Simon, Kevin Bishop, Raman Sood, Fabio CandottiAbstract:The adenylate kinase (AK) gene family consists of 7 different members that contribute to energy cell metabolism by converting ATP+AMP to 2ADP. AKs are critical players in ensuring cellular energy homeostasis in all tissues. Mutations in the AK2 gene are responsible for reticular dysgenesis (RD), an autosomal recessive form of severe combined immunodeficiency (SCID). RD is characterized by an early differentiation arrest in the granulocyte lineage and impaired lymphoid maturation and it represents less than 2% of total SCID. Affected children succumb to overwhelming infections early in life unless their immune system is successfully restored with allogeneic hematopoietic stem cells transplant (HSCT). The mechanisms underlying the pathophysiology of RD remain unclear. The phenotype of AK2 deficient animals has never been reported in the literature, but murine lines carrying homozygous inactivating retroviral insertions are embryonically lethal (our personal observations). We used the zebrafish model to perform a comprehensive study of the effects of AK2 deficiency using Morpholino oligomers injections and two different kinds of AK2 mutants (a ENU-induced T371C/L124P missense mutant and two null mutant lines generated using zinc-finger nuclease technology). In situ hybridization analyses of AK2-deficient embryos indicated that only erythroid development was affected during primitive hematopoiesis. Conversely, during definitive hematopoiesis, the loss of function of AK2 resulted in abnormalities distributed along all hematopoietic lineages suggesting an impairment of hematopoietic stem cell (HSC) development. Moreover, we observed that the AK2 deficiency induced oxidative stress and consequent apoptosis in both primitive erythroid cells and definitive HSCs. Importantly, antioxidant treatment of AK2 mutant embryos rescued the hematopoietic phenotypes as indicated by the recovered expression of HSC and lymphoid markers (such as c-myb and rag1). Overall, our data indicate that zebrafish represents a good model for studying the molecular mechanisms involved in RD and testing of new therapeutic interventions. To date, our mutant lines remain the only animal model of this rare and lethal human disease. Disclosures: No relevant conflicts of interest to declare.
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Adenylate Kinase 2 Regulates Zebrafish Primitive and Definitive Hematopoiesis
Blood, 2012Co-Authors: Alberto Rissone, Kevin Bishop, Trevor Blake, Raman Sood, Jaya Jagadeesh, Simon Karen, Fabio CandottiAbstract:Abstract 1208 Introduction: The adenylate kinase (AK) gene family consists of 7 different members that contribute to energy cell metabolism by converting ATP + AMP to 2 molecules of ADP. AKs are critical players in ensuring cellular energy homeostasis in all tissues and are generally involved in a broad range of cellular functions. Among AKs, AK2 has unique features such as its location in the mitochondrial intermembrane space and critical role in human lymphopoiesis and granulopoiesis. Indeed, mutations of the AK2 gene cause reticular dysgenesis (RD), an autosomal recessive form of severe combined immunodeficiency (SCID) characterized by an early differentiation arrest in the granulocyte lineage and impaired lymphoid maturation. The mechanisms underlying the pathophysiology of RD remain unclear. The phenotype of AK2 deficient animals has not been reported in the literature, but murine lines carrying homozygous inactivating retroviral insertions are embryonically lethal (our personal observations). Objectives: To study the role of AK2 in hematopoietic system development and define the effects of AK2 deficiency, we set out to generate a zebrafish model of RD. Methods: We injected zebrafish embryos with morpholino oligomers specific for the two zebrafish AK2 isoforms and analyzed the serial expression pattern of several hematopoietic markers in developing AK2 morphants. To confirm our observations in AK2 knockdown embryos, we screened a zebrafish DNA library of ENU-induced mutations and recovered a mutant fish line carrying a T371C/L124P missense mutation within the exon 4 of AK2 gene that is predicted to be deleterious for protein stability and function. Results: The downregulation of zebrafish AK2 expression phenocopied the human disease and resulted in strong reduction of developing lymphocytes. In addition, in situ hybridization for GATA1, alpha-globin 1, L-plastin and Odianisidine staining indicated that erythroid development was affected in AK2 morphants during primitive hematopoiesis, while myeloid development was conserved. Furthermore, in situ hybridization studies of the expression of markers of zebrafish definitive hematopoiesis showed abnormalities distributed among all hematopoietic lineages suggesting a broad role of AK2 in zebrafish hematopoiesis. Importantly, the ENU-induced AK2 mutant recapitulated all the primitive and definitive hematopoietic phenotypes observed in AK2 morphants. Finally, preliminary data suggest that AK2 deficiency (both in morphant and mutant embryos) induces an increased level of reactive oxygen species (ROS) triggering oxidative stress and consequent apoptosis in hematopoietic progenitor cells. Conclusions: Our data provide new insights into the AK2 function and indicate that zebrafish represents a good model for studying the molecular mechanisms involved in RD. To date, our mutant line represents the first example of animal model of this rare and unique human disease. Disclosures: No relevant conflicts of interest to declare.
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characterization of AK2 gene function in zebrafish hematopoiesis
Blood, 2011Co-Authors: Alberto Rissone, Guridevi Jayashree Jagadeesh, Karen L Simon, Kevin Bishop, Milton A English, Trevor Blake, Robert M Nissen, Raman Sood, Fabio CandottiAbstract:Abstract 2185 Objective: The Adenylate Kinase (AK) gene family consists of 7 different members (AK1-7) that contribute to energy metabolism of the cells by converting ATP (or GTP) and free AMP to ADP (or GDP) and free ADP. AKs are critical players in ensuring cellular energy homeostasis in all tissues and are generally involved in a broad range of cellular functions. Among AKs, AK2 is uniquely located in the mitochondrial intermembrane space and has been implicated in Caspase 10-mediated apoptosis, although the published data remain controversial. More recently, it was demonstrated that mutations of the AK2 gene cause reticular dysgenesis, an autosomal recessive form of severe combined immunodeficiency (SCID). Reticular dysgenesis is characterized by an early differentiation arrest in the granulocyte lineage and impaired lymphoid maturation resulting in overwhelming infections and high lethality in affected patients. Moreover, patients commonly present with bilateral sensorineural deafness. The mechanisms underlying the biological consequences of AK2-defieincy remain unclear and the generation and characterization study of model systems is expected to provide useful insigths. AK2 gene-targeted mice have not been reported in the literature, but lines carrying homozygous inactivating retroviral insertions have been shown to be embryonically lethal (our unpublished observations). Because of the known advantages of zebrafish as model system for developmental studies and the similarities of hematopoiesis in zebrafish and higher vertebrates, we set out to investigate the function of the zebrafish AK2 gene in development, with particular emphasis on hematopoiesis. Results: Similar to humans, we found that two different alternatively spliced isoforms of the AK2 gene (Isoform A and Isoform B) are expressed in zebrafish. By Real-Time PCR and In situ Hybridization (ISH) we analyzed the expression of both AK2 isoforms during embryo development. Preliminary data indicate that Isoform A is more abundantly represented than Isoform B during embryo development. ISH analysis showed that the two isoforms have different spatial expression patterns. These data suggest different functionalities for AK2 isoforms during embryo development. To explore such hypothesis, we injected two different morpholinos (MOs) targeting the AK2 isoforms. Downregulation of both AK2 isoforms phenocopied the human disease and resulted in a strong reduction of developing lymphocytes. Moreover we observed a hypochromic phenotype that also suggested impairment of the erythroid lineage. ISH experiments are underway to better define the affected hematopoietic lineages. Interestingly, AK2 MOs-injected embryos showed also developmental defects beyond the hematopoietic system, such as abnormal jaw development. Future studies will focus on the characterization of the specific function of the alternatively spliced AK2 isoforms. Conclusions: We show that the transcription features of the AK2 gene are conserved in zebrafish. The observed differential expression patterns of the zebrafish AK2 isoforms may provide new insights into the function of AK2 in the development of the hematopoietic system, as well as other organs and offers prospects for the understanding of the molecular mechanisms involved in reticular dysgenesis. Disclosures: No relevant conflicts of interest to declare.
Kevin Bishop - One of the best experts on this subject based on the ideXlab platform.
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a model for reticular dysgenesis shows impaired sensory organ development and hair cell regeneration linked to cellular stress
Disease Models & Mechanisms, 2019Co-Authors: Alberto Rissone, Kevin Bishop, Raman Sood, Fabio Candotti, Erin Jimenez, Blake Carrington, Claire Slevin, Stephen Wincovitch, Shawn M BurgessAbstract:ABSTRACT Mutations in the gene AK2 are responsible for reticular dysgenesis (RD), a rare and severe form of primary immunodeficiency in children. RD patients have a severely shortened life expectancy and without treatment die, generally from sepsis soon after birth. The only available therapeutic option for RD is hematopoietic stem cell transplantation (HSCT). To gain insight into the pathophysiology of RD, we previously created zebrafish models for AK2 deficiencies. One of the clinical features of RD is hearing loss, but its pathophysiology and causes have not been determined. In adult mammals, sensory hair cells of the inner ear do not regenerate; however, their regeneration has been observed in several non-mammalian vertebrates, including zebrafish. Therefore, we used our RD zebrafish models to determine whether AK2 deficiency affects sensory organ development and/or hair cell regeneration. Our studies indicated that AK2 is required for the correct development, survival and regeneration of sensory hair cells. Interestingly, AK2 deficiency induces the expression of several oxidative stress markers and it triggers an increased level of cell death in the hair cells. Finally, we show that glutathione treatment can partially rescue hair cell development in the sensory organs in our RD models, pointing to the potential use of antioxidants as a therapeutic treatment supplementing HSCT to prevent or ameliorate sensorineural hearing deficits in RD patients.
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a model for reticular dysgenesis shows impaired sensory organ development and hair cell regeneration linked to cellular stress
bioRxiv, 2019Co-Authors: Alberto Rissone, Kevin Bishop, Raman Sood, Fabio Candotti, Erin Jimenez, Blake Carrington, Claire Slevin, Stephen Wincovitch, Shawn M BurgessAbstract:Mutations in the gene AK2 are responsible for Reticular Dysgenesis (RD), a rare and severe form of primary immunodeficiency in children. RD patients have a severely shortened life expectancy and without treatment die a few weeks after birth. The only available therapeutic option for RD is bone marrow transplantation. To gain insight into the pathophysiology of RD, we previously created zebrafish models for an AK2 deficiency. One of the clinical features of RD is hearing loss, but its pathology and causes have not been determined. In adult mammals, sensory hair cells of the inner ear do not regenerate; however, their regeneration has been observed in several non-mammalian vertebrates, including zebrafish. Therefore, we use our RD zebrafish models to determine if AK2 deficiency affects sensory organ development and/or hair cell regeneration. Our studies indicated that AK2 is required for the correct development, survival and regeneration of sensory hair cells. Interestingly, AK2 deficiency induces the expression of several oxidative stress markers and it triggers an increased level of cell death in the hair cells. Finally, we show that glutathione treatment can partially rescue hair cell development in the sensory organs in our RD models, pointing to the potential use of antioxidants as a supportive therapeutic modality for RD patients, not only to increase their chances of survival, but to prevent or ameliorate their sensorineural hearing deficits.
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reticular dysgenesis associated AK2 protects hematopoietic stem and progenitor cell development from oxidative stress
Journal of Experimental Medicine, 2015Co-Authors: Alberto Rissone, Katja G Weinacht, Kevin Bishop, Giancarlo La Marca, Elisa Giocaliere, Jayashree Jagadeesh, Kerstin Felgentreff, Kerry Dobbs, Waleed AlherzAbstract:Adenylate kinases (AKs) are phosphotransferases that regulate the cellular adenine nucleotide composition and play a critical role in the energy homeostasis of all tissues. The AK2 isoenzyme is expressed in the mitochondrial intermembrane space and is mutated in reticular dysgenesis (RD), a rare form of severe combined immunodeficiency (SCID) in humans. RD is characterized by a maturation arrest in the myeloid and lymphoid lineages, leading to early onset, recurrent, and overwhelming infections. To gain insight into the pathophysiology of RD, we studied the effects of AK2 deficiency using the zebrafish model and induced pluripotent stem cells (iPSCs) derived from fibroblasts of an RD patient. In zebrafish, AK2 deficiency affected hematopoietic stem and progenitor cell (HSPC) development with increased oxidative stress and apoptosis. AK2-deficient iPSCs recapitulated the characteristic myeloid maturation arrest at the promyelocyte stage and demonstrated an increased AMP/ADP ratio, indicative of an energy-depleted adenine nucleotide profile. Antioxidant treatment rescued the hematopoietic phenotypes in vivo in AK2 mutant zebrafish and restored differentiation of AK2-deficient iPSCs into mature granulocytes. Our results link hematopoietic cell fate in AK2 deficiency to cellular energy depletion and increased oxidative stress. This points to the potential use of antioxidants as a supportive therapeutic modality for patients with RD.
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Reticular dysgenesis–associated AK2 protects hematopoietic stem and progenitor cell development from oxidative stress
Journal of Experimental Medicine, 2015Co-Authors: Alberto Rissone, Katja G Weinacht, Kevin Bishop, Waleed Al-herz, Giancarlo La Marca, Elisa Giocaliere, Jayashree Jagadeesh, Kerstin Felgentreff, Kerry Dobbs, Marypat JonesAbstract:Adenylate kinases (AKs) are phosphotransferases that regulate the cellular adenine nucleotide composition and play a critical role in the energy homeostasis of all tissues. The AK2 isoenzyme is expressed in the mitochondrial intermembrane space and is mutated in reticular dysgenesis (RD), a rare form of severe combined immunodeficiency (SCID) in humans. RD is characterized by a maturation arrest in the myeloid and lymphoid lineages, leading to early onset, recurrent, and overwhelming infections. To gain insight into the pathophysiology of RD, we studied the effects of AK2 deficiency using the zebrafish model and induced pluripotent stem cells (iPSCs) derived from fibroblasts of an RD patient. In zebrafish, AK2 deficiency affected hematopoietic stem and progenitor cell (HSPC) development with increased oxidative stress and apoptosis. AK2-deficient iPSCs recapitulated the characteristic myeloid maturation arrest at the promyelocyte stage and demonstrated an increased AMP/ADP ratio, indicative of an energy-depleted adenine nucleotide profile. Antioxidant treatment rescued the hematopoietic phenotypes in vivo in AK2 mutant zebrafish and restored differentiation of AK2-deficient iPSCs into mature granulocytes. Our results link hematopoietic cell fate in AK2 deficiency to cellular energy depletion and increased oxidative stress. This points to the potential use of antioxidants as a supportive therapeutic modality for patients with RD.
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AK2 deficiency in zebrafish recapitulates human reticular dysgenesis an autosomal recessive form of severe combined immunodeficiency
Blood, 2013Co-Authors: Jaya Jagadeesh, Karen L Simon, Kevin Bishop, Raman Sood, Fabio CandottiAbstract:The adenylate kinase (AK) gene family consists of 7 different members that contribute to energy cell metabolism by converting ATP+AMP to 2ADP. AKs are critical players in ensuring cellular energy homeostasis in all tissues. Mutations in the AK2 gene are responsible for reticular dysgenesis (RD), an autosomal recessive form of severe combined immunodeficiency (SCID). RD is characterized by an early differentiation arrest in the granulocyte lineage and impaired lymphoid maturation and it represents less than 2% of total SCID. Affected children succumb to overwhelming infections early in life unless their immune system is successfully restored with allogeneic hematopoietic stem cells transplant (HSCT). The mechanisms underlying the pathophysiology of RD remain unclear. The phenotype of AK2 deficient animals has never been reported in the literature, but murine lines carrying homozygous inactivating retroviral insertions are embryonically lethal (our personal observations). We used the zebrafish model to perform a comprehensive study of the effects of AK2 deficiency using Morpholino oligomers injections and two different kinds of AK2 mutants (a ENU-induced T371C/L124P missense mutant and two null mutant lines generated using zinc-finger nuclease technology). In situ hybridization analyses of AK2-deficient embryos indicated that only erythroid development was affected during primitive hematopoiesis. Conversely, during definitive hematopoiesis, the loss of function of AK2 resulted in abnormalities distributed along all hematopoietic lineages suggesting an impairment of hematopoietic stem cell (HSC) development. Moreover, we observed that the AK2 deficiency induced oxidative stress and consequent apoptosis in both primitive erythroid cells and definitive HSCs. Importantly, antioxidant treatment of AK2 mutant embryos rescued the hematopoietic phenotypes as indicated by the recovered expression of HSC and lymphoid markers (such as c-myb and rag1). Overall, our data indicate that zebrafish represents a good model for studying the molecular mechanisms involved in RD and testing of new therapeutic interventions. To date, our mutant lines remain the only animal model of this rare and lethal human disease. Disclosures: No relevant conflicts of interest to declare.
T B Karegoudar - One of the best experts on this subject based on the ideXlab platform.
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Efficient decolorization and detoxification of sulphonated azo dye Ponceau 4R by using single and mixed bacterial consortia
Biocatalysis and Biotransformation, 2019Co-Authors: Ramesh S Masarbo, T R Monisha, Anand S Nayak, S. R. Niranjana, T B KaregoudarAbstract:The decolorization of toxic azo dye Ponceau 4R by three strains of bacteria Bacillus sp. strain AK1, Lysinibacillus sp. strain AK2 and Kerstersia sp. strain VKY1 individually and in consortia was s...
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enhanced decolorization of sulfonated azo dye methyl orange by single and mixed bacterial strains ak1 AK2 and vky1
Bioremediation Journal, 2018Co-Authors: Ramesh S Masarbo, Mukram Ismailsab, T R Monisha, Anand S Nayak, T B KaregoudarAbstract:AbstractMethyl orange, a sulfonated azo dye having various industrial applications was decolorized by three bacteria Bacillus sp. strain AK1, Lysinibacillus sp. strain AK2 and Kerstersia sp. strain VKY1. The effect of various factors such as dye concentration, pH, temperature and NaCl concentration on decolorization was investigated. At 200 mg/L methyl orange concentration, the strains AK1, AK2 and VKY1 exhibited maximum decolorizing potential of 93, 95 and 96%, respectively, at temperature 35 °C and pH 7.0 within 18 h of incubation. These strains decolorized the dye over a wide range of pH (5–10), temperature (15–55 °C), and NaCl concentration (5–20 g/L). Further, these strains decolorize up to 800 mg/L concentrations of methyl orange within 24 h. The dye decolorization efficiency was further increased by using different consortia of these three strains which could decolorize the dye completely within 12 h of incubation. The cell-free extracts of the strains AK1, AK2 and VKY1 grown on methyl orange exhib...
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decolorization of sulfonated azo dye metanil yellow by newly isolated bacterial strains bacillus sp strain ak1 and lysinibacillus sp strain AK2
Journal of Hazardous Materials, 2011Co-Authors: O Anjaneya, Yogesh S Souche, M Santoshkumar, T B KaregoudarAbstract:Abstract Two different bacterial strains capable of decolorizing a highly water soluble azo dye Metanil Yellow were isolated from dye contaminated soil sample collected from Atul Dyeing Industry, Bellary, India. The individual bacterial strains Bacillus sp. AK1 and Lysinibacillus sp. AK2 decolorized Metanil Yellow (200 mg L −1 ) completely within 27 and 12 h respectively. Various parameters like pH, temperature, NaCl and initial dye concentrations were optimized to develop an economically feasible decolorization process. The maximum concentration of Metanil Yellow (1000 mg L −1 ) was decolorized by strains AK2 and AK1 within 78 and 84 h respectively. These strains could decolorize Metanil Yellow over a broad pH range 5.5–9.0; the optimum pH was 7.2. The decolorization of Metanil Yellow was most efficient at 40 °C and confirmed by UV–visible spectroscopy, TLC, HPLC and GC/MS analysis. Further, both the strains showed the involvement of azoreductase in the decolorization process. Phytotoxicity studies of catabolic products of Metanil Yellow on the seeds of chick pea and pigeon pea revealed much reduction in the toxicity of metabolites as compared to the parent dye. These results indicating the effectiveness of strains AK1 and AK2 for the treatment of textile effluents containing azo dyes.
Katja G Weinacht - One of the best experts on this subject based on the ideXlab platform.
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Adenylate Kinase 2 Links Energy Metabolism and Cell Fate in Hematopoietic Stem and Progenitor Cells
Blood, 2019Co-Authors: Wenqing Wang, Avni Awani, Andrew Devilbiss, Thomas P. Mathews, Daniel Thomas, Daniel P. Dever, Matthew H. Porteus, Sean J. Morrison, Katja G WeinachtAbstract:While hematopoietic stem and progenitor cells (HSPCs) were thought to rely mainly on glycolysis for energy supply, emerging evidence suggests that defects in mitochondrial functions can impact HSPC development with respect to self-renewal, differentiation and aging. The exact mechanisms underlying metabolic reprogramming and cell fate decisions during human hematopoiesis, however, remain elusive. Biallelic mutations in the mitochondrial enzyme adenylate kinase 2 (AK2), cause reticular dysgenesis (RD), one of the most profound forms of severe combined immunodeficiency (SCID). AK2 catalyzes the interconversion between adenine nucleotides and thereby controls the availability of ADP for oxidative phosphorylation. Clinically, RD patients not only present with profound lymphopenia, typical for classic SCID, but also suffer from severe congenital neutropenia. The developmental arrest across the T, NK and granulocytic lineages suggests that AK2 deficiency causes a metabolic defect with global impact on hematopoiesis. Our prior work in induced pluripotent stem cells (iPSCs) from RD patients has shown that maturation-arrested iPSC-derived HSPCs exhibit increased oxidative stress and an energy-depleted adenine nucleotide profile, suggesting that AK2-regulated mitochondrial bioenergetics play an integral role in HSPC differentiation. Therefore, RD serves as an excellent model to study the impact of mitochondrial metabolism during human HSPC development. Methods: Since iPSCs do not recapitulate definitive hematopoiesis, we developed an AK2 biallelic knock-out model in primary human HSPCs using CRISPR/Cas9 gene editing. Employing a homologous recombination-mediated dual color reporter strategy, we were able to select for HSPCs with biallelic AK2 knock-out. HSPCs edited at the safe harbor AAVS1 site were used as a control. FACS purified AK2-/- and AAVS1-/- HSPCs were in vitro differentiated along the granulocytic lineage, and cells at various differentiation stages were sorted for RNA-seq and metabolomics analysis. Results: We analyzed the myeloid differentiation potential of AK2-/- HSPCs in vitro. Compared to AAVS1-/- controls, AK2-/- HSPCs displayed a severely decreased colony forming potential of both myeloid and erythroid lineages. In addition, AK2-/- HSPCs showed a granulocytic maturation arrest at the HLA-DR-, CD117+ promyelocyte stage, consistent with the characteristic phenotype observed in RD patients. We then performed RNA-seq studies on in vitro differentiated promyelocyte and neutrophil subpopulations derived from AK2-/- and control HSPCs. The RNA-seq analysis showed differential gene expression in glutathione metabolism and IL-10 signaling pathways, suggesting an increase in oxidative stress and inflammation, respectively, caused by AK2 deficiency. In addition, genes implicated in antimicrobial function and granule synthesis were downregulated in AK2-/- neutrophils, suggesting a functional defect. Liquid chromatography-mass spectrometry (LC-MS/MS) studies to delineate differences in metabolite profile conferred by AK2 deficiency at different stages of HSPC development are currently in progress. Conclusions: We have established the first cell-traceable biallelic AK2 CRISPR knock-out model in primary human HSPCs that recapitulates the myeloid phenotype of RD patients. This model allows us to profile AK2 knock-out cells at different developmental stages. AK2-/- granulocyte precursors showed a transcriptional signature suggestive of worsening oxidative stress, inflammation and defective effector cell functions during maturation. To understand the mechanistic underpinnings for these observations we are now using a global metabolomics approach to profile the changes in energy metabolites that occur during development in AK2-deficient and control HSPC subpopulations. Understanding how metabolism governs differentiation and self-renewal of human HSPCs has important translational implications to improve hematopoietic stem cell products and transplantation outcomes. Disclosures Morrison: Frequency Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; OncoMed Pharmaceuticals: Equity Ownership; GI Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Kolon Gene Therapeutics: Consultancy; Protein Fluidics: Other: Stock Options.
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An Engineered Cell-Traceable Model of Reticular Dysgenesis in Human Hematopoietic Stem Cells Linking Metabolism and Differentiation
Blood, 2018Co-Authors: Wenqing Wang, Avni Awani, Daniel Thomas, Daniel P. Dever, Matthew H. Porteus, Lauren Reich, Yusuke Nakauchi, Katja G WeinachtAbstract:Abstract Hematopoietic stem cell (HSC) differentiation is accompanied by a metabolic shift from glycolysis to oxidative phosphorylation (OXPHOS) to meet the increasing energy demand during proliferation and differentiation. However, the role of mitochondrial metabolism in HSC differentiation goes beyond ATP production. Metabolites generated during mitochondrial metabolism may impact in HSC fate decisions through stable epigenetic modifications. Despite some progress in understanding mitochondrial communication during HSC development, their role in human hematopoiesis remains largely elusive, where the lack of appropriate model systems poses a major obstacle. Reticular Dysgenesis (RD), a rare and particularly severe form of severe combined immunodeficiency (SCID), offers an attractive model for studying the role of mitochondrial metabolism in hematopoiesis. RD is an autosomal recessive disease caused by biallelic mutations of the mitochondrial enzyme Adenylate Kinase 2 (AK2). AK2 catalyzes the reversible phosphorylation of adenosine monophosphate (AMP) to adenosine diphosphate (ADP), which serves as the substrate for the ATP synthase. In addition to defective lymphocyte development typical of classic SCID, RD patients also suffer from impaired myeloid development, suggestive of a global defect in hematopoiesis. In a human induced pluripotent stem cell (iPSC) model for RD, hematopoietic stem and progenitor cells (HSPCs) recapitulate a profound maturation arrest of the myeloid lineage, increased oxidative stress and an energy-depleted metabolite and transcriptional profile. We hypothesize that AK2 defects drive hematopoietic cell fate decisions through changes in metabolites that regulate the activities of DNA/histone modifying enzymes and result in stable epigenetic modifications. Methods: Since iPSCs are not suitable to model the epigenetic characteristics of definitive hematopoiesis, we developed a novel model system in which we deleted AK2 in primary human HSCs using CRISPR/Cas9 gene editing technique. We found a highly effective single-guide RNA (sgRNA) targeting the catalytic LID domain of the AK2 gene to introduce directed DNA double stranded breaks (DSBs), and use a homologous recombination (HR)-mediated dual reporter system to track and isolate cells with biallelic AK2 disruption. Results: Our single-color GFP reporter system consistently produces a >60% GFP+ population of AK2-targeted CD34+ umbilical cord blood (UCB) cells. With dual GFP/BFP reporters, we were able to achieve 6% GFP/BFP double positive cells with confirmed biallelic AK2 knock-out. Since HR events on one allele are biologically linked to CRISPR/Cas9 mediated DSBs on the other, we assessed insertion and/or deletion (INDEL) frequency and protein expression in a single reporter (GFP+) population of AK2-targeted UCBs. We detected an INDEL frequency of over 90% on the non-HR alleles along with nearly absent AK2 protein expression by Western Blot. These results indicated that the highly efficient single-color reporter system with >60% targeting efficiency is sufficient to achieve an AK2 biallelic knock-out population in primary HSCs. in vitro myeloid differentiation of these AK2-targeted HSCs recapitulates the RD phenotype with impaired neutrophil but preserved monocyte development. Conclusion: This novel disease model for RD will now allow us to examine the cellular and molecular impact of perturbations in metabolism on human HSC development. We will investigate the effect on differentiation potential, metabolite profile, transcriptome and epigenome in vitro as well as in a xenograft mouse model. Elucidating how metabolism governs differentiation and self-renewal of human HSCs will not only advance our basic understanding of many blood and immune diseases, but has important translational implications for improving the use of HSCs in hematopoietic stem cell transplantation, gene and cell therapy. Disclosures Porteus: CRISPR Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees.
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reticular dysgenesis associated AK2 protects hematopoietic stem and progenitor cell development from oxidative stress
Journal of Experimental Medicine, 2015Co-Authors: Alberto Rissone, Katja G Weinacht, Kevin Bishop, Giancarlo La Marca, Elisa Giocaliere, Jayashree Jagadeesh, Kerstin Felgentreff, Kerry Dobbs, Waleed AlherzAbstract:Adenylate kinases (AKs) are phosphotransferases that regulate the cellular adenine nucleotide composition and play a critical role in the energy homeostasis of all tissues. The AK2 isoenzyme is expressed in the mitochondrial intermembrane space and is mutated in reticular dysgenesis (RD), a rare form of severe combined immunodeficiency (SCID) in humans. RD is characterized by a maturation arrest in the myeloid and lymphoid lineages, leading to early onset, recurrent, and overwhelming infections. To gain insight into the pathophysiology of RD, we studied the effects of AK2 deficiency using the zebrafish model and induced pluripotent stem cells (iPSCs) derived from fibroblasts of an RD patient. In zebrafish, AK2 deficiency affected hematopoietic stem and progenitor cell (HSPC) development with increased oxidative stress and apoptosis. AK2-deficient iPSCs recapitulated the characteristic myeloid maturation arrest at the promyelocyte stage and demonstrated an increased AMP/ADP ratio, indicative of an energy-depleted adenine nucleotide profile. Antioxidant treatment rescued the hematopoietic phenotypes in vivo in AK2 mutant zebrafish and restored differentiation of AK2-deficient iPSCs into mature granulocytes. Our results link hematopoietic cell fate in AK2 deficiency to cellular energy depletion and increased oxidative stress. This points to the potential use of antioxidants as a supportive therapeutic modality for patients with RD.
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Reticular dysgenesis–associated AK2 protects hematopoietic stem and progenitor cell development from oxidative stress
Journal of Experimental Medicine, 2015Co-Authors: Alberto Rissone, Katja G Weinacht, Kevin Bishop, Waleed Al-herz, Giancarlo La Marca, Elisa Giocaliere, Jayashree Jagadeesh, Kerstin Felgentreff, Kerry Dobbs, Marypat JonesAbstract:Adenylate kinases (AKs) are phosphotransferases that regulate the cellular adenine nucleotide composition and play a critical role in the energy homeostasis of all tissues. The AK2 isoenzyme is expressed in the mitochondrial intermembrane space and is mutated in reticular dysgenesis (RD), a rare form of severe combined immunodeficiency (SCID) in humans. RD is characterized by a maturation arrest in the myeloid and lymphoid lineages, leading to early onset, recurrent, and overwhelming infections. To gain insight into the pathophysiology of RD, we studied the effects of AK2 deficiency using the zebrafish model and induced pluripotent stem cells (iPSCs) derived from fibroblasts of an RD patient. In zebrafish, AK2 deficiency affected hematopoietic stem and progenitor cell (HSPC) development with increased oxidative stress and apoptosis. AK2-deficient iPSCs recapitulated the characteristic myeloid maturation arrest at the promyelocyte stage and demonstrated an increased AMP/ADP ratio, indicative of an energy-depleted adenine nucleotide profile. Antioxidant treatment rescued the hematopoietic phenotypes in vivo in AK2 mutant zebrafish and restored differentiation of AK2-deficient iPSCs into mature granulocytes. Our results link hematopoietic cell fate in AK2 deficiency to cellular energy depletion and increased oxidative stress. This points to the potential use of antioxidants as a supportive therapeutic modality for patients with RD.
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linking oxidative stress to cell fate ipsc based disease modeling identifies new therapeutic target in reticular dysgenesis
Blood, 2014Co-Authors: Katja G WeinachtAbstract:Reticular Dysgenesis (RD) is one of the most serious forms of severe combined immune deficiency (SCID). It is characterized by complete absence of circulating lymphocytes and neutrophils. In addition, patients suffer from sensorineural hearing loss. Before newborn screening for SCID was implemented, the majority of patients succumbed to infection long before hematopoietic cell transplantation (HCT) could be attempted. To this date, the prognosis for RD remains grim. RD is caused by mutations in the mitochondrial ADP-generator Adenylate Kinase 2 (AK2). AK1 is a cytosolic protein that may compensate in various tissues for the lack of AK2. However, AK1 is not expressed in leukocytes and the stria vascularis of the inner ear [1]. While this observation may explain where AK2 defects manifest, the molecular mechanisms how AK2 defects take effect, remain largely obscure. Significant obstacles to elucidating disease pathology have been the lack of a suitable animal models and the unavailability of patient specimens. Using skin fibroblasts from an RD-patient we have recently identified at Boston Children’s Hospital [2], we have generated induced pluripotent stem cells (iPSC) with homozygous loss of function mutation in AK2. In-vitro myeloid differentiation of AK2-mutated iPSCs recapitulates the characteristic maturation arrest at the promyelocyte stage observed in-vivo in patients with this condition. AK2 is expressed in the intermitochondrial space and serves as primary mitochondrial ADP generator by promoting the reversible reaction AMP + ATP = 2 ADP. Maintenance of adequate levels of ADP is critical to support ATP synthase activity. Using Mass Spectrometry, we have shown that decreased AK2 activity leads to an increase in the AMP/ADP ratio in iPS-derived myeloid cells, indicating that AK2 is indispensable in maintaining ADP supply in the myeloid lineage. We have also performed transcriptome analysis of AK2- mutated myeloid cells compared to control and found a significant down regulation of ATP-dependant transporters. Based on this data, we hypothesized that in patients with RD, ADP-depletion in myeloid progenitors leads to stage 4 respiration, a well defined state in mitochondrial biology, in which the ATP-synthase lacks substrate and decreases its activity. This causes a reduction in proton flux from the intermitochondrial space back into the matrix, transient rise in membrane potential, and an escalation in the formation of reactive oxygen species (ROS). The cell responds by activating “inducible uncoupling”, the opening of alternative proton pores, which allows proton flux back into the matrix, bypassing the ATP-synthase and foregoing the use of energy stored in the proton gradient. While this represents a cellular rescue mechanism in response to acute oxidative stress, extended oxidative-stress-induced uncoupling eventually leads to a decline in proton gradient and membrane potential and ultimately in demise of the cell. To test this hypothesis, we have added Glutathione, the primary endogenous cellular antioxidant, to the culture conditions. We also tested G-CSF and all-trans-retinoic acid (ATRA), agents known to promote promyelocyte differentiation to mature neutrophils in other conditions. While G-CSF had no, and ATRA clearly deleterious effects on myeloid maturation in AK2-mutated cells, Glutathione led to a significant improvement in differentiation, allowing development of mature neutrophils in-vitro . Our results suggest that cell fate in RD is linked to oxidative stress and identify antioxidants as a possible therapeutic approach that may help reduce early mortality due to severe infections in patients with RD. Disclosures No relevant conflicts of interest to declare.
