Prostacyclin is an endosteal bone marrow niche component and its clinical analog iloprost protects hematopoietic stem cell potential during stress.

Hematopoietic stem cells (HSCs) with superior reconstitution potential are reported to be enriched in the endosteal compared to central bone marrow (BM) region. To investigate whether specific factors at the endosteum may contribute to HSC potency, we screened for candidate HSC niche factors enriched in the endosteal compared to central BM regions. Together with key known HSC supporting factors Kitl and Cxcl12, we report that prostacyclin/prostaglandin I2 (PGI2 ) synthase (Ptgis) was one of the most highly enriched mRNAs (>10-fold) in endosteal compared to central BM. As PGI2 signals through receptors distinct from prostaglandin E2 (PGE2 ), we investigated functional roles for PGI2 at the endosteal niche using therapeutic PGI2 analogs, iloprost, and cicaprost. We found PGI2 analogs strongly reduced HSC differentiation in vitro. Ex vivo iloprost pulse treatment also significantly boosted long-term competitive repopulation (LT-CR) potential of HSCs upon transplantation. This was associated with increased tyrosine-phosphorylation of transducer and activator of transcription-3 (STAT3) signaling in HSCs but not altered cell cycling. In vivo, iloprost administration protected BM HSC potential from radiation or granulocyte colony-stimulating factor-induced exhaustion, and restored HSC homing potential with increased Kitl and Cxcl12 transcription in the BM. In conclusion, we propose that PGI2 is a novel HSC regulator enriched in the endosteum that promotes HSC regenerative potential following stress.

Neonatal factors related to survival and intellectual and developmental outcome of patients with early-onset urea cycle disorders.

PURPOSE: We aimed to identify prognostic factors for survival and long-term intellectual and developmental outcome in neonatal patients with early-onset urea cycle disorders (UCD) experiencing hyperammonaemic coma. METHODS: We retrospectively analysed ammonia (NH3) and glutamine levels, electroencephalogram and brain images obtained during neonatal coma of UCD patients born between 1995 and 2011 and managed at a single centre and correlated them to survival and intellectual and developmental outcome. RESULTS: We included 38 neonates suffering from deficiencies of argininosuccinate synthetase (ASSD, N = 12), ornithine transcarbamylase (OTCD, N = 10), carbamoylphosphate synthetase 1 (CPSD, N = 7), argininosuccinate lyase (ASLD, N = 7), N-acetylglutamate synthase (NAGS, N = 1) or arginase (ARGD, N = 1). Symptoms occurred earlier in mitochondrial than in cytosolic UCD. Sixty-eight percent of patients survived, with a mean (standard deviation-SD) follow-up of 10.4 (5.3) years. Mortality was mostly observed in OTCD (N = 7/10) and CPSD (N = 4/7) patients. Plasma NH3 level during the neonatal period, expressed as area under the curve, but not glutamine level was associated with mortality (p = .044 and p = .610). 62.1% of the patients had normal intellectual and developmental outcome. Intellectual and developmental outcome tended to correlate with UCD subtype (p = .052). No difference in plasma NH3 or glutamine level during the neonatal period among developmental outcomes was identified. EEG severity was linked to UCD subtypes (p = .004), ammonia levels (p = .037), duration of coma (p = .043), and mortality during the neonatal period (p = .020). Status epilepticus was recorded in 6 patients, 3 of whom died neonatally, 1 developed a severe intellectual disability while the 2 last patients had a normal development. CONCLUSION: UCD subtypes differed by survival rate, intellectual and developmental outcome and EEG features in the neonatal period. Hyperammonaemia expressed as area under the curve was associated with survival but not with intellectual and developmental outcome whereas glutamine was not associated with one of these outcomes. Prognostic value of video-EEG monitoring and the association between status epilepticus and mortality should be assessed in neonatal hyperammonaemic coma in further studies.

Autism spectrum disorders in propionic acidemia patients.

Propionic acidemia is the result of a deficiency in propionyl-CoA carboxylase activity. Chronic neurologic and cognitive complications frequently occur, but the psychiatric evolution of the disorder is not well documented. We conducted a pedopsychiatric evaluation of 19 children, adolescents and young adults, aged between 2 and 25 years, using ADI-R, CARS-T, as well as ADOS when autism spectrum disorder was suspected. Previous psychometric examinations were also taken into consideration. Thirteen patients had an IQ < 80. Two patients presented with autism and two additional patients with other autism spectrum disorders. Five patients did not fulfill diagnostic criteria for autism spectrum disorder but showed difficulties indicative of a broader autism phenotype (BAP). Four other patients had severe anxiety manifestations related to their disease. Two patients presented with acute psychotic episodes. The number of decompensations in the first 3 years of life was lower in patients with autism spectrum disorder or related symptoms. These patients were also older when they were assessed (median age of 15 years old versus 11 years old). There was no significant correlation between 3-hydroxypropionate levels during the first 6 years of life and autism spectrum disorder diagnosis. In conclusion, autism spectrum disorder is frequent in patients with propionic acidemia. These patients should undergo in-depth psychiatric evaluation and be screened for autism spectrum disorder. Further studies are needed to understand the underlying mechanisms.

Long-term metabolic follow-up and clinical outcome of 35 patients with maple syrup urine disease.

BACKGROUND: Maple syrup urine disease (MSUD) is a rare disease that requires a protein-restricted diet for successful management. Little is known, however, about the psychosocial outcome of MSUD patients. This study investigates the relationship between metabolic and clinical parameters and psychosocial outcomes in a cohort of patients with neonatal-onset MSUD. METHODS: Data on academic achievement, psychological care, family involvement, and biochemical parameters were collected from the medical records of neonatal MSUD patients treated at Necker Hospital (Paris) between 1964 and 2013. RESULTS: Thirty-five MSUD patients with a mean age of 16.3 (2.1-49.0) years participated. Metabolic decompensations (plasma leucine >380 µmol/L) were more frequent during the first year of life and after 15 years, mainly due to infection and dietary noncompliance, respectively. Leucine levels increased significantly in adulthood: 61.5% of adults were independent and achieved adequate social and professional integration; 56% needed occasional or sustained psychological or psychiatric care (8/19, with externalizing, mood, emotional, and anxiety disorders being the most common). Patients needing psychiatric care were significantly older [mean and standard deviation (SD) 22.6 (7.7) years] than patients needing only psychological follow-up [mean (SD) 14.3 (8.9) years]. Patients with psychological follow-up experienced the highest lifetime number of decompensations; 45% of families had difficulty coping with the chronic disease. Parental involvement was negatively associated with the number of lifetime decompensations. CONCLUSION: Adults had increased levels of plasma leucine, consistent with greater chronic toxicity. Psychological care was associated with age and number of decompensations. In addition, parental involvement appeared to be crucial in the management of MSUD patients.

Neurocognitive profiles in MSUD school-age patients.

Maple syrup urine disease (MSUD), an inborn error of amino acids catabolism is characterized by accumulation of branched chain amino acids (BCAAs) leucine, isoleucine, valine and their corresponding alpha-ketoacids. Impact on the cognitive development has been reported historically, with developmental delays of varying degree. Currently, earlier diagnosis and improved management allow a better neurodevelopment, without requirement of special education. However, specific impairments can be observed, and so far, results of detailed neurocognitive assessments are not available. The aim of this study was to analyse neurocognitive profiles of French MSUD patients. This was a multicentre retrospective study on MSUD patients who underwent neurocognitive evaluation at primary school age. Twenty-one patients with classical neonatal onset MSUD were included. The patients' mean age at the time of evaluation was 8.7 years. The mean intellectual quotient (IQ) score was in the normal range (95.1 ± 12.6). In a subset of eight patients, a consistent developmental pattern of higher verbal than performance IQ was observed (mean of the difference 25.7 ± 8.7, p < 0.0001). No correlation could be established between this pattern and long-term metabolic balance (BCAA blood levels), or severity of acute metabolic imbalances, or leucine blood levels at diagnosis and time to toxin removal procedure. These data show that some MSUD patients may exhibit an abnormal neurocognitive profile with higher verbal than performance abilities. This might suggest an executive dysfunction disorder that would need to be further investigated by specialized testing. This pattern is important to detect in MSUD, as appropriate neuropsychological treatment strategies should be proposed.

Interaction of c-Myb with p300 is required for the induction of acute myeloid leukemia (AML) by human AML oncogenes.

The MYB oncogene is widely expressed in acute leukemias and is important for the continued proliferation of leukemia cells, suggesting that MYB may be a therapeutic target in these diseases. However, realization of this potential requires a significant therapeutic window for MYB inhibition, given its essential role in normal hematopoiesis, and an approach for developing an effective therapeutic. We previously showed that the interaction of c-Myb with the coactivator CBP/p300 is essential for its transforming activity. Here, by using cells from Booreana mice which carry a mutant allele of c-Myb, we show that this interaction is essential for in vitro transformation by the myeloid leukemia oncogenes AML1-ETO, AML1-ETO9a, MLL-ENL, and MLL-AF9. We further show that unlike cells from wild-type mice, Booreana cells transduced with AML1-ETO9a or MLL-AF9 retroviruses fail to generate leukemia upon transplantation into irradiated recipients. Finally, we have begun to explore the molecular mechanisms underlying these observations by gene expression profiling. This identified several genes previously implicated in myeloid leukemogenesis and HSC function as being regulated in a c-Myb-p300-dependent manner. These data highlight the importance of the c-Myb-p300 interaction in myeloid leukemogenesis and suggest disruption of this interaction as a potential therapeutic strategy for acute myeloid leukemia.

Neurological heterotopic ossification following spinal cord injury is triggered by macrophage-mediated inflammation in muscle.

Neurological heterotopic ossification (NHO) is the abnormal formation of bone in soft tissues as a consequence of spinal cord or traumatic brain injury. NHO causes pain, ankyloses, vascular and nerve compression and delays rehabilitation in this high-morbidity patient group. The pathological mechanisms leading to NHO remain unknown and consequently there are no therapeutic options to prevent or reduce NHO. Genetically modified mouse models of rare genetic forms of heterotopic ossification (HO) exist, but their relevance to NHO is questionable. Consequently, we developed the first model of spinal cord injury (SCI)-induced NHO in genetically unmodified mice. Formation of NHO, measured by micro-computed tomography, required the combination of both SCI and localized muscular inflammation. Our NHO model faithfully reproduced many clinical features of NHO in SCI patients and both human and mouse NHO tissues contained macrophages. Muscle-derived mesenchymal progenitors underwent osteoblast differentiation in vitro in response to serum from NHO mice without additional exogenous osteogenic stimuli. Substance P was identified as a candidate NHO systemic neuropeptide, as it was significantly elevated in the serum of NHO patients. However, antagonism of substance P receptor in our NHO model only modestly reduced the volume of NHO. In contrast, ablation of phagocytic macrophages with clodronate-loaded liposomes reduced the size of NHO by 90%, supporting the conclusion that NHO is highly dependent on inflammation and phagocytic macrophages in soft tissues. Overall, we have developed the first clinically relevant model of NHO and demonstrated that a combined insult of neurological injury and soft tissue inflammation drives NHO pathophysiology.

Pharmacologic stabilization of HIF-1α increases hematopoietic stem cell quiescence in vivo and accelerates blood recovery after severe irradiation.

UNLABELLED: Quiescent hematopoietic stem cells (HSCs) preferentially reside in poorly perfused niches that may be relatively hypoxic. Most of the cellular effects of hypoxia are mediated by O2-labile hypoxia-inducible transcription factors (HIFs). To investigate the effects of hypoxia on HSCs, we blocked O2-dependent HIF-1α degradation in vivo in mice by injecting 2 structurally unrelated prolyl hydroxylase domain (PHD) enzyme inhibitors: dimethyloxalyl glycine and FG-4497. Injection of either of these 2 PHD inhibitors stabilized HIF-1α protein expression in the BM. In vivo stabilization of HIF-1a with these PHD inhibitors increased the proportion of phenotypic HSCs and immature hematopoietic progenitor cells in phase G0 of the cell cycle and decreased their proliferation as measured by 5-bromo-2'-deoxyuridine incorporation. This effect was independent of erythropoietin, the expression of which was increased in response to PHD inhibitors. Finally, pretreatment of mice with a HIF-1α stabilizer before severe, sublethal 9.0-Gy irradiation improved blood recovery and enhanced 89-fold HSC survival in the BM of irradiated mice as measured in long-term competitive repopulation assays. The results of the present study demonstrate that the levels of HIF-1α protein can be manipulated pharmacologically in vivo to increase HSC quiescence and recovery from irradiation. KEY POINTS: HIF-1α protein stabilization increases HSC quiescence in vivo. HIF-1α protein stabilization increases HSC resistance to irradiation and accelerates recovery.

B-lymphopoiesis is stopped by mobilizing doses of G-CSF and is rescued by overexpression of the anti-apoptotic protein Bcl2.

Osteoblasts are necessary to B lymphopoiesis and mobilizing doses of G-CSF or cyclophosphamide inhibit osteoblasts, whereas AMD3100/Plerixafor does not. However, the effect of these mobilizing agents on B lymphopoiesis has not been reported. Mice (wild-type, knocked-out for TNF-α and TRAIL, or over-expressing Bcl-2) were mobilized with G-CSF, cyclophosphamide, or AMD3100. Bone marrow, blood, spleen and lymph node content in B cells was measured. G-CSF stopped medullar B lymphopoiesis with concomitant loss of B-cell colony-forming units, pre-pro-B, pro-B, pre-B and mature B cells and increased B-cell apoptosis by an indirect mechanism. Overexpression of the anti-apoptotic protein Bcl2 in transgenic mice rescued B-cell colony forming units and pre-pro-B cells in the marrow, and prevented loss of all B cells in marrow, blood and spleen. Blockade of endogenous soluble TNF-α with Etanercept, or combined deletion of the TNF-α and TRAIL genes did not prevent B lymphopoiesis arrest in response to G-CSF. Unlike G-CSF, treatments with cyclophosphamide or AMD3100 did not suppress B lymphopoiesis but caused instead robust B-cell mobilization. G-CSF, cyclophosphamide and AMD3100 have distinct effects on B lymphopoiesis and B-cell mobilization with: 1) G-CSF inhibiting medullar B lymphopoiesis without mobilizing B cells in a mechanism distinct from the TNF-α-mediated loss of B lymphopoiesis observed during inflammation or viral infections; 2) CYP mobilizing B cells but blocking their maturation; and 3) AMD3100 mobilizing B cells without affecting B lymphopoiesis. These results suggest that blood mobilized with these three agents may have distinct immune properties.

Bacterial Lipopolysaccharides Exacerbate Neurogenic Heterotopic Ossification Development.

Neurogenic heterotopic ossifications (NHO) are heterotopic bones that develop in periarticular muscles after severe central nervous system (CNS) injuries. Several retrospective studies have shown that NHO prevalence is higher in patients who suffer concomitant infections. However, it is unclear whether these infections directly contribute to NHO development or reflect the immunodepression observed in patients with CNS injury. Using our mouse model of NHO induced by spinal cord injury (SCI) between vertebrae T11 to T13 , we demonstrate that lipopolysaccharides (LPS) from gram-negative bacteria exacerbate NHO development in a toll-like receptor-4 (TLR4)-dependent manner, signaling through the TIR-domain-containing adapter-inducing interferon-ß (TRIF/TICAM1) adaptor rather than the myeloid differentiation primary response-88 (MYD88) adaptor. We find that T11 to T13 SCI did not significantly alter intestinal integrity nor cause intestinal bacteria translocation or endotoxemia, suggesting that NHO development is not driven by endotoxins from the gut in this model of SCI-induced NHO. Relevant to the human pathology, LPS increased expression of osteoblast markers in cultures of human fibro-adipogenic progenitors isolated from muscles surrounding NHO biopsies. In a case-control retrospective study in patients with traumatic brain injuries, infections with gram-negative Pseudomonas species were significantly associated with NHO development. Together these data suggest a functional association between gram-negative bacterial infections and NHO development and highlights infection management as a key consideration to avoid NHO development in patients. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Long term follow-up after haematopoietic stem cell transplantation for mucopolysaccharidosis type I-H: a retrospective study of 51 patients.

Mucopolysaccharidosis type I-H (MPS I-H) is a rare lysosomal storage disorder caused by α-L-Iduronidase deficiency. Early haematopoietic stem cell transplantation (HSCT) is the sole available therapeutic option to preserve neurocognitive functions. We report long-term follow-up (median 9 years, interquartile range 8-16.5) for 51 MPS I-H patients who underwent HSCT between 1986 and 2018 in France. 4 patients died from complications of HSCT and one from disease progression. Complete chimerism and normal α-L-Iduronidase activity were obtained in 84% and 71% of patients respectively. No difference of outcomes was observed between bone marrow and cord blood stem cell sources. All patients acquired independent walking and 91% and 78% acquired intelligible language or reading and writing. Intelligence Quotient evaluation (n = 23) showed that 69% had IQ ≥ 70 at last follow-up. 58% of patients had normal or remedial schooling and 62% of the 13 adults had good socio-professional insertion. Skeletal dysplasia as well as vision and hearing impairments progressed despite HSCT, with significant disability. These results provide a long-term assessment of HSCT efficacy in MPS I-H and could be useful in the evaluation of novel promising treatments such as gene therapy.

Positioning of bone marrow hematopoietic and stromal cells relative to blood flow in vivo: serially reconstituting hematopoietic stem cells reside in distinct nonperfused niches.

Hematopoietic stem cell (HSC) niches have been reported at the endosteum or adjacent to bone marrow (BM) vasculature. To investigate functional attributes of these niches, mice were perfused with Hoechst 33342 (Ho) in vivo before BM cell collection in presence of pump inhibitors and antibody stained. We report that the position of phenotypic HSCs, multipotent and myeloid progenitors relative to blood flow, follows a hierarchy reflecting differentiation stage, whereas mesenchymal stromal cells are perivascular. Furthermore, during granulocyte colony-stimulating factor-induced mobilization, HSCs migrated closer to blood flow, whereas stromal cells did not. Interestingly, phenotypic Lin(-)Sca1(+)KIT(+)CD41(-)CD48(-)CD150(+) HSCs segregated into 2 groups (Ho(neg) or Ho(med)), based on degree of blood/Ho perfusion of their niche. HSCs capable of serial transplantation and long-term bromodeoxyuridine label retention were enriched in Ho(neg) HSCs, whereas Ho(med) HSCs cycled more frequently and only reconstituted a single host. This suggests that the most potent HSC niches are enriched in locally secreted factors and low oxygen tension due to negligible blood flow. Importantly, blood perfusion of niches correlates better with HSC function than absolute distance from vasculature. This technique enables prospective isolation of serially reconstituting HSCs distinct from other less potent HSCs of the same phenotype, based on the in vivo niche in which they reside.

Bone marrow macrophages maintain hematopoietic stem cell (HSC) niches and their depletion mobilizes HSCs.

In the bone marrow, hematopoietic stem cells (HSCs) reside in specific niches near osteoblast-lineage cells at the endosteum. To investigate the regulation of these endosteal niches, we studied the mobilization of HSCs into the bloodstream in response to granulocyte colony-stimulating factor (G-CSF). We report that G-CSF mobilization rapidly depletes endosteal osteoblasts, leading to suppressed endosteal bone formation and decreased expression of factors required for HSC retention and self-renewal. Importantly, G-CSF administration also depleted a population of trophic endosteal macrophages (osteomacs) that support osteoblast function. Osteomac loss, osteoblast suppression, and HSC mobilization occurred concomitantly, suggesting that osteomac loss could disrupt endosteal niches. Indeed, in vivo depletion of macrophages, in either macrophage Fas-induced apoptosis (Mafia) transgenic mice or by administration of clodronate-loaded liposomes to wild-type mice, recapitulated the: (1) loss of endosteal osteoblasts and (2) marked reduction of HSC-trophic cytokines at the endosteum, with (3) HSC mobilization into the blood, as observed during G-CSF administration. Together, these results establish that bone marrow macrophages are pivotal to maintain the endosteal HSC niche and that the loss of such macrophages leads to the egress of HSCs into the blood.

Treatment by oral creatine, L-arginine and L-glycine in six severely affected patients with creatine transporter defect.

BACKGROUND: X-linked cerebral creatine deficiency is caused by the deficiency of the creatine transporter (CTP) encoded by the SLC6A8 gene. PATIENTS AND METHODS: We report here a series of six patients with severe CTP deficiency, four males and two females; clinical presentations include mild to severe mental retardation (6/6), associated with psychiatric symptoms (5/6: autistic behaviour, chronic hallucinatory psychosis), seizures (2/6) and muscular symptoms (2/4 males). Diagnosis was suspected upon elevated urinary creatine/creatinine (except in one of the female patients) and on a markedly decreased creatine peak on magnetic resonance spectroscopy (MRS). Diagnosis was confirmed by molecular analysis that identified four novel mutations not reported so far, including a mutation found twice in two male patients. All patients were treated successively and according to the same protocol by creatine alone then combined to its precursors, L-glycine and L-arginine for 42 months. RESULTS AND CONCLUSION: In our patients, creatine supplementation alone or with its precursors L-glycine and L-arginine showed benefit only in the muscular symptoms of the disease and no improvement in the cognitive and psychiatric manifestations and did not modify brain creatine content on MRS of male and female CTP deficient patients. New treatment strategies are required including creatine derivatives transported independently from CTP or using alternative pathways and transporters.

Oncostatin M regulates hematopoietic stem cell (HSC) niches in the bone marrow to restrict HSC mobilization.

We show that pro-inflammatory oncostatin M (OSM) is an important regulator of hematopoietic stem cell (HSC) niches in the bone marrow (BM). Treatment of healthy humans and mice with granulocyte colony-stimulating factor (G-CSF) dramatically increases OSM release in blood and BM. Using mice null for the OSM receptor (OSMR) gene, we demonstrate that OSM provides a negative feed-back acting as a brake on HSPC mobilization in response to clinically relevant mobilizing molecules G-CSF and CXCR4 antagonist. Likewise, injection of a recombinant OSM molecular trap made of OSMR complex extracellular domains enhances HSC mobilization in poor mobilizing C57BL/6 and NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ mice. Mechanistically, OSM attenuates HSC chemotactic response to CXCL12 and increases HSC homing to the BM signaling indirectly via BM endothelial and mesenchymal cells which are the only cells expressing OSMR in the BM. OSM up-regulates E-selectin expression on BM endothelial cells indirectly increasing HSC proliferation. RNA sequencing of HSCs from Osmr-/- and wild-type mice suggest that HSCs have altered cytoskeleton reorganization, energy usage and cycling in the absence of OSM signaling in niches. Therefore OSM is an important regulator of HSC niche function restraining HSC mobilization and anti-OSM therapy combined with current mobilizing regimens may improve HSPC mobilization for transplantation.

Initial presentation, management and follow-up data of 33 treated patients with hereditary tyrosinemia type 1 in the absence of newborn screening.

Hereditary tyrosinemia type 1 (HT1) is a rare autosomal recessive disorder of phenylalanine and tyrosine catabolism due to a deficiency of fumarylacetoacetate hydrolase. HT1 has a large clinical spectrum with acute forms presenting before six months of age, subacute forms with initial symptoms occurring between age 6 and 12 months, and chronic forms after 12 months of age. Without treatment, HT1 results in the accumulation of toxic metabolites leading to liver disease, proximal tubular dysfunction, and porphyria-like neurological crises. Since the early nineties, the outcome of HT1 has dramatically changed due to its treatment with 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC, nitisinone). In some countries, HT1 is included in the newborn screening program based on the analysis of succinylacetone concentration on dried blood spots. In the present study, we report clinical and laboratory parameters data on 33 HT1 patients focusing on clinical presentation and therapeutic management at the time of diagnosis. Eighteen patients were diagnosed with the acute form (median age at presentation 2.5 months), 6 with the subacute form (median age at presentation 10 months), and 5 with the chronic form of HT1 (median age at presentation 15 months). Four patients were diagnosed pre-symptomatically in the setting of a family history of HT1. Among the 29 symptomatic patients, hepatomegaly was found in 83% of patients and prolonged coagulation times due to hepatocellular insufficiency was observed in 93% of patients. HT1 diagnosis was confirmed by increased urine succinylacetone in all patients. All patients but 2 were treated with nitisinone immediately at diagnosis. During follow-up, 2 patients received liver transplant for high grade dysplasia or hepatocellular carcinoma, 10 patients exhibited some form of neurocognitive impairments. Our data confirm that HT1 is a severe treatable liver disease that should be detected at the earliest, ideally by newborn screening and appropriately treated.

Clinical and biochemical heterogeneity associated with fumarase deficiency.

Fumarase deficiency (FD), caused by biallelic alteration of the Fumarase Hydratase gene (FH), and a rare metabolic disorder that affects the Krebs cycle, causes severe neurological impairment and fumaric aciduria. Less than 30 unrelated cases are known to date. In addition, heterozygous mutations of the FH gene are responsible for hereditary leiomyomatosis and renal cell cancer (HLRCC). We report three additional patients with dramatically different clinical presentations of FD and novel missense mutations in the FH gene. One patient had severe neonatal encephalopathy, polymicrogyria, <1% enzyme activity, and mildly increased levels of urinary fumarate. The second patient had microcephaly, mental retardation, 20% of fumarase activity, and intermediate levels of urinary fumarate. The third patient had mild mental retardation, polymicrogyria, 42-61% enzyme activity in different cell types and massive amounts of urinary fumarate. In silico analysis predicted minor yet significant structural changes in the encoded proteins. The nuclear translocation of hypoxia-inducible factor (HIF)-1alpha (HIF1A) in cultured fibroblasts was similar to controls. These results extend the range of clinical and biochemical variation associated with FD, supporting the notion that patients with moderate increases in fumarate excretion should be investigated for this disease. The tumoral risk in the patients and their relatives requires adequate screening protocols.

Enteral tube feeding in patients receiving dietary treatment for metabolic diseases: A retrospective analysis in a large French cohort.

CONTEXT: A strictly controlled diet (often involving enteral tube feeding (ETF)) is part of the treatment of many inherited metabolic diseases (IMDs). OBJECTIVE: To describe the use of ETF in a large cohort of patients with IMDs. DESIGN: A retrospective analysis of ETF in patients with urea cycle disorders (UCDs), organic aciduria (OA), maple syrup disease (MSUD), glycogen storage diseases (GSDs) or fatty acid oxidation disorders (FAODs) diagnosed before the age of 12 months. SETTING: The reference center for IMDs at Necker Hospital (Paris, France). RESULTS: 190 patients born between January 1991 and August 2017 were being treated for OA (n = 60), UCDs (n = 55), MSUD (n = 32), GSDs (n = 26) or FAODs (n = 17). Ninety-eight of these patients (52%) received ETF (OA subgroup: n = 40 (67%); UCDs: n = 12 (22%); MSUD: n = 9 (28%); GSDs: n = 23 (88%); FAODs: n = 14 (82%)). Indications for ETF were feeding difficulties in 64 (65%) patients, cessation of fasting in 39 (40%), and recurrent metabolic decompensation in 14 (14%). Complications of ETF were recorded in 48% of cases, more frequently with nasogastric tube (NGT) than with gastrostomy. Among patients in whom ETF was withdrawn, the mean duration of ETF was 5.9 (SD: 4.8) years (range: 0.6-19.8 years). The duration of ETF was found to vary from one disease subgroup to another (p = 0.051). While the longest median duration was found in the GSD subgroup (6.8 years), the shortest one was found in the UCD subgroup (0.9 years). CONCLUSION: ETF is an integral part of the dietary management of IMDs. The long duration of ETF and the specific risks of NGT highlights the potential value of gastrostomy.In this study at a French tertiary hospital, we documented the indications, modalities, duration and complications of enteral tube feeding in a cohort of patients with inherited metabolic diseases.

Acute Myeloid Leukemia Chemo-Resistance Is Mediated by E-selectin Receptor CD162 in Bone Marrow Niches.

The interactions of leukemia cells with the bone marrow (BM) microenvironment is critical for disease progression and resistance to treatment. We have recently found that the vascular adhesion molecule E-(endothelial)-selectin is a key niche component that directly mediates acute myeloid leukemia (AML) chemo-resistance, revealing E-selectin as a promising therapeutic target. To understand how E-selectin promotes AML survival, we investigated the potential receptors on AML cells involved in E-selectin-mediated chemo-resistance. Using CRISPR-Cas9 gene editing to selectively suppress canonical E-selectin receptors CD44 or P-selectin glycoprotein ligand-1 (PSGL-1/CD162) from human AML cell line KG1a, we show that CD162, but not CD44, is necessary for E-selectin-mediated chemo-resistance in vitro. Using preclinical models of murine AML, we then demonstrate that absence of CD162 on AML cell surface leads to a significant delay in the onset of leukemia and a significant increase in sensitivity to chemotherapy in vivo associated with a more rapid in vivo proliferation compared to wild-type AML and a lower BM retention. Together, these data reveal for the first time that CD162 is a key AML cell surface receptor involved in AML progression, BM retention and chemo-resistance. These findings highlight specific blockade of AML cell surface CD162 as a potential novel niche-based strategy to improve the efficacy of AML therapy.

Bacterial Lipopolysaccharides Suppress Erythroblastic Islands and Erythropoiesis in the Bone Marrow in an Extrinsic and G- CSF-, IL-1-, and TNF-Independent Manner.

Anemia of inflammation (AI) is the second most prevalent anemia after iron deficiency anemia and results in persistent low blood erythrocytes and hemoglobin, fatigue, weakness, and early death. Anemia of inflammation is common in people with chronic inflammation, chronic infections, or sepsis. Although several studies have reported the effect of inflammation on stress erythropoiesis and iron homeostasis, the mechanisms by which inflammation suppresses erythropoiesis in the bone marrow (BM), where differentiation and maturation of erythroid cells from hematopoietic stem cells (HSCs) occurs, have not been extensively studied. Here we show that in a mouse model of acute sepsis, bacterial lipopolysaccharides (LPS) suppress medullary erythroblastic islands (EBIs) and erythropoiesis in a TLR-4- and MyD88-dependent manner with concomitant mobilization of HSCs. LPS suppressive effect on erythropoiesis is indirect as erythroid progenitors and erythroblasts do not express TLR-4 whereas EBI macrophages do. Using cytokine receptor gene knock-out mice LPS-induced mobilization of HSCs is G-CSF-dependent whereas LPS-induced suppression of medullary erythropoiesis does not require G- CSF-, IL- 1-, or TNF-mediated signaling. Therefore suppression of medullary erythropoiesis and mobilization of HSCs in response to LPS are mechanistically distinct. Our findings also suggest that EBI macrophages in the BM may sense innate immune stimuli in response to acute inflammation or infections to rapidly convert to a pro-inflammatory function at the expense of their erythropoietic function.