Empagliflozin for treating neutropenia and neutrophil dysfunction in 21 infants with glycogen storage disease 1b

Empagliflozin has been successfully repurposed for treating neutropenia and neutrophil dysfunction in patients with glycogen storage disease type 1b (GSD 1b), however, data in infants are missing. We report on efficacy and safety of empagliflozin in infants with GSD 1b. This is an international retrospective case series on 21 GSD 1b infants treated with empagliflozin (total treatment time 20.6 years). Before starting empagliflozin (at a median age of 8.1 months with a median dose of 0.3 mg/kg/day) 12 patients had clinical signs and symptoms of neutrophil dysfunction. Six of these previously symptomatic patients had no further neutropenia/neutrophil dysfunction-associated findings on empagliflozin. Eight patients had no signs and symptoms of neutropenia/neutrophil dysfunction before start and during empagliflozin treatment. One previously asymptomatic individual with a horseshoe kidney developed a central line infection with pyelonephritis and urosepsis during empagliflozin treatment. Of the 10 patients who were treated with G-CSF before starting empagliflozin, this was stopped in four and decreased in another four. Eleven individuals were never treated with G-CSF. While in 17 patients glucose homeostasis remained stable on empagliflozin, four showed glucose homeostasis instability in the introductory phase. In 17 patients, no other side effects were reported, while genital (n = 2) or oral (n = 1) candidiasis and skin infection (n = 1) were reported in the remaining four. Empagliflozin had a good effect on neutropenia/neutrophil dysfunction-related signs and symptoms and a favourable safety profile in infants with GSD 1b and therefore qualifies for further exploration as first line treatment.

Brain function in classic galactosemia, a galactosemia network (GalNet) members review

Classic galactosemia (CG, OMIM #230400, ORPHA: 79,239) is a hereditary disorder of galactose metabolism that, despite treatment with galactose restriction, affects brain function in 85% of the patients. Problems with cognitive function, neuropsychological/social emotional difficulties, neurological symptoms, and abnormalities in neuroimaging and electrophysiological assessments are frequently reported in this group of patients, with an enormous individual variability. In this review, we describe the role of impaired galactose metabolism on brain dysfunction based on state of the art knowledge. Several proposed disease mechanisms are discussed, as well as the time of damage and potential treatment options. Furthermore, we combine data from longitudinal, cross-sectional and retrospective studies with the observations of specialist teams treating this disease to depict the brain disease course over time. Based on current data and insights, the majority of patients do not exhibit cognitive decline. A subset of patients, often with early onset cerebral and cerebellar volume loss, can nevertheless experience neurological worsening. While a large number of patients with CG suffer from anxiety and depression, the increased complaints about memory loss, anxiety and depression at an older age are likely multifactorial in origin.

Imerslund-Gräsbeck syndrome: a comprehensive review of reported cases

Imerslund-Gräsbeck syndrome (IGS) is a rare autosomal recessive disorder characterized by vitamin B12 malabsorption. Most patients present with non-specific symptoms attributed to vitamin B12 deficiency, and proteinuria. Patients may if untreated, develop severe neurocognitive manifestations. If recognized and treated with sufficient doses of vitamin B12, patients recover completely. We provide, for the first time, an overview of all previously reported cases of IGS. In addition, we provide a complete review of IGS and describe two new patients.

Metachromatic leukodystrophy: To screen or not to screen?

Metachromatic leukodystrophy (MLD) is a neurodegenerative lysosomal storage disorder caused by biallelic pathogenic variants in the gene encoding arylsulfatase A. Disease onset is variable (with late infantile, early and late juvenile, and adult forms) and treatment options depend on age and disease symptoms at onset. In the past, allo-hematopoietic stem cell transplantation (allo-HSCT) has been the best treatment option, following strict selection criteria. The outcome however is variable and morbidity remains high. This paved the way to the development of new treatment options, some of them aiming to be curative. In the light of this changing therapeutic field, newborn screening is becoming a valuable option. This narrative review aims to describe the outcome of allo-HSCT in the different MLD disease forms, and, in addition, reviews new treatment options. Finally, the shift of the field towards newborn screening for MLD is discussed.

Recurrent Isolated Sixth Nerve Palsy in Childhood-Review on a Rare Phenomenon

Sixth nerve palsy is an ominous sign in pediatric neurology. Due to the long and tortuous course of the sixth (abducens) nerve, it is generally considered a sign of intracranial pathology. Sixth nerve palsy is associated with increased intracranial pressure and neoplasms, among other less frequent causes. In ∼5 to 15% of cases, no cause can be identified. These cases are classified as idiopathic or "benign" and recovery is typically complete. A recurrence of symptoms is very rare. We provide a rare case report of recurrent benign sixth nerve palsy in a 5-year-old child. In addition, we provide an overview of all earlier published cases of recurrent isolated sixth nerve palsy. To date, only 72 pediatric patients with recurrent isolated sixth nerve palsy have been reported. Young females with left-sided sixth nerve palsy and recent immunization are at risk of recurrence. Pathophysiological mechanisms have been discussed, but have yet to be clarified. Recurrent isolated sixth nerve palsy is only rarely associated with severe causes and the need for extensive investigation may be questioned.

MPS I: Early diagnosis, bone disease and treatment, where are we now?

Mucopolysaccharidosis type I (MPS I) is a lysosomal storage disorder characterized by α-L-iduronidase deficiency. Patients present with a broad spectrum of disease severity ranging from the most severe phenotype (Hurler) with devastating neurocognitive decline, bone disease and early death to intermediate (Hurler-Scheie) and more attenuated (Scheie) phenotypes, with a normal life expectancy. The most severely affected patients are preferably treated with hematopoietic stem cell transplantation, which halts the neurocognitive decline. Patients with more attenuated phenotypes are treated with enzyme replacement therapy. There are several challenges to be met in the treatment of MPS I patients. First, to optimize outcome, early recognition of the disease and clinical phenotype is needed to guide decisions on therapeutic strategies. Second, there is thus far no effective treatment available for MPS I bone disease. The pathophysiological mechanisms behind bone disease are largely unknown, limiting the development of effective therapeutic strategies. This article is a state of the art that comprehensively discusses three of the most urgent open issues in MPS I: early diagnosis of MPS I patients, pathophysiology of MPS I bone disease, and emerging therapeutic strategies for MPS I bone disease.

Are GMI gangliosidosis and Morquio type B two different disorders or part of one phenotypic spectrum?

Monosialotetrahexosylganglioside (GMI) gangliosidosis and Morquio type B (MorB) are two lysosomal storage disorders (LSDs) caused by the same enzyme deficiency, β-galactosidase (βgal). GMI gangliosidosis, associated with GMI ganglioside accumulation, is a neurodegenerative condition characterized by psychomotor regression, visceromegaly, cherry red spot, and facial and skeletal abnormalities. MorB is characterized by prominent and severe skeletal deformities due to keratan sulfate (KS) accumulation. There are only a few reports on intermediate phenotypes between GMI gangliosidosis and MorB. The presentation of two new patients with this rare intermediate phenotype motivated us to review the literature, to study differences and similarities between GMI gangliosidosis and MorB, and to speculate about the possible mechanisms that may contribute to the differences in clinical presentation. In conclusion, we hypothesize that GMI gangliosidosis and MorB are part of one phenotypic spectrum of the same disease and that the classification of LSDs might need to be revised.

Altered interaction and distribution of glycosaminoglycans and growth factors in mucopolysaccharidosis type I bone disease

The mucopolysaccharidoses (MPSs) comprise a group of lysosomal storage disorders characterized by deficient degradation and subsequent accumulation of glycosaminoglycans (GAGs). Progressive bone and joint disease are a major cause of morbidity, and current therapeutic strategies have limited effect on these symptoms. By elucidating pathophysiological mechanisms underlying bone disease, new therapeutic targets may be identified. Longitudinal growth is regulated by interaction between GAGs and growth factors. Because GAGs accumulate in the MPSs, we hypothesized that altered interaction between growth factors and GAGs contribute to the pathogenesis of MPS bone disease. In this study, binding between GAGs from MPS I chondrocytes and fibroblast growth factor 2 (FGF2) was not significantly different from binding of FGF2 to GAGs from control chondrocytes. FGF2 signaling, however, was increased in MPS I chondrocytes after incubation with FGF2, as compared to control chondrocytes. Using bone cultures, we demonstrated decreased growth of WT mouse bones after incubation with FGF2, but no effect on MPS I bone growth. However, MPS I bones showed decreased growth in the presence of GAGs from MPS I chondrocytes. Finally, we demonstrate altered GAG distribution in MPS I chondrocytes, and altered GAG, FGF2 and Indian hedgehog distribution in growth plates from MPS I mice. In summary, our results suggest that altered interaction and distribution of growth factors and accumulated GAGs may contribute to the pathogenesis of MPS bone disease. In the future, targeting growth factor regulation or the interaction between in growth factors and GAGs might be a promising therapeutic strategy for MPS bone disease.

Adverse Effects of Genistein in a Mucopolysaccharidosis Type I Mouse Model

Mucopolysaccharidosis type I (MPS I) is a lysosomal storage disorder characterized by diminished degradation of the glycosaminoglycans heparan sulfate (HS) and dermatan sulfate (DS). Patients present with a variety of symptoms, including severe skeletal disease. Current therapeutic strategies have only limited effects on bone disease. The isoflavone genistein has been studied as a potential therapy for the mucopolysaccharidoses because of its putative ability to inhibit GAG synthesis and subsequent accumulation. Cell, animal, and clinical studies, however, showed variable outcomes. To determine the effects of genistein on MPS I-related bone disease, wild-type (WT) and MPS I mice were fed a genistein-supplemented diet (corresponding to a dose of approximately 160 mg/kg/day) for 8 weeks. HS and DS levels in bone and plasma remained unchanged after genistein supplementation, while liver HS levels were decreased in genistein-fed MPS I mice as compared to untreated MPS I mice. Unexpectedly, genistein-fed mice exhibited significantly decreased body length and femur length. In addition, 60% of genistein-fed MPS I mice developed a scrotal hernia and/or scrotal hydrocele, manifestations, which were absent in WT or untreated MPS I mice. In contrast to studies in MPS III mice, our study in MPS I mice demonstraes no beneficial but even potential adverse effects of genistein supplementation. Our results urge for a cautious approach on the use of genistein, at least in patients with MPS I.

Epidemiology and diagnosis of lysosomal storage disorders; challenges of screening

The lysosomal storage disorders (LSDs) are a group of genetic disorders resulting from defective lysosomal metabolism and subsequent accumulation of substrates. Patients present with a large phenotypic spectrum of disease manifestations that are generally not specific for LSDs, leading to considerable diagnostic delay and missed cases. Introduction of new disease modifying therapies for LSDs has made early diagnosis a priority. Increased awareness, but particularly the introduction of screening programs allow for early diagnosis and timely initiation of treatment. This review will provide insight into the epidemiology and diagnostic process for LSDs. In addition, challenges for carrier screening, high-risk screening and newborn population screening for LSDs are discussed.

Genistein increases glycosaminoglycan levels in mucopolysaccharidosis type I cell models

Mucopolysaccharidosis type I (MPS I) is a lysosomal storage disorder characterized by diminished degradation of the glycosaminoglycans (GAGs) heparan sulfate and dermatan sulfate, which results in the accumulation of these GAGs and subsequent cellular dysfunction. Patients present with a variety of symptoms, including severe skeletal disease. Genistein has been shown previously to inhibit GAG synthesis in MPS fibroblasts, presumably through inhibition of tyrosine kinase activity of the epidermal growth factor receptor (EGFR). To determine the potentials of genistein for the treatment of skeletal disease, MPS I fibroblasts were induced into chondrocytes and osteoblasts and treated with genistein. Surprisingly, whereas tyrosine phosphorylation levels (as a measure for tyrosine kinase inhibition) were decreased in all treated cell lines, there was a 1.3 and 1.6 fold increase in GAG levels in MPS I chondrocytes and fibroblast, respectively (p < 0.05). Sulfate incorporation in treated MPS I fibroblasts was 2.6 fold increased (p < 0.05), indicating increased GAG synthesis despite tyrosine kinase inhibition. This suggests that GAG synthesis is not exclusively regulated through the tyrosine kinase activity of the EGFR. We hypothesize that the differences in outcomes between studies on the effect of genistein in MPS are caused by the different effects of genistein on different growth factor signaling pathways, which regulate GAG synthesis. More studies are needed to elucidate the precise signaling pathways which are affected by genistein and alter GAG metabolism in order to evaluate the therapeutic potential of genistein for MPS patients.

An algorithm to predict phenotypic severity in mucopolysaccharidosis type I in the first month of life

Introduction

Mucopolysaccharidosis type I (MPS I) is a progressive multisystem lysosomal storage disease caused by deficiency of the enzyme α-L-iduronidase (IDUA). Patients present with a continuous spectrum of disease severity, and the most severely affected patients (Hurler phenotype; MPS I-H) develop progressive cognitive impairment. The treatment of choice for MPS I-H patients is haematopoietic stem cell transplantation, while patients with the more attenuated phenotypes benefit from enzyme replacement therapy.

The potential of newborn screening (NBS) for MPS I is currently studied in many countries. NBS for MPS I, however, necessitates early assessment of the phenotype, in order to decide on the appropriate treatment. In this study, we developed an algorithm to predict phenotypic severity in newborn MPS I patients.

Methods

Thirty patients were included in this study. Genotypes were collected from all patients and all patients were phenotypically categorized at an age of > 18 months based on the clinical course of the disease. In 18 patients, IDUA activity in fibroblast cultures was measured using an optimized IDUA assay. Clinical characteristics from the first month of life were collected from 23 patients.

Results

Homozygosity or compound heterozygosity for specific mutations which are associated with MPS I-H, discriminated a subset of patients with MPS I-H from patients with more attenuated phenotypes (specificity 100%, sensitivity 82%). Next, we found that enzymatic analysis of IDUA activity in fibroblasts allowed identification of patients affected by MPS I-H. Therefore, residual IDUA activity in fibroblasts was introduced as second step in the algorithm. Patients with an IDUA activity of < 0.32 nmol x mg^-1 × hr^-1 invariably were MPS I-H patients, while an IDUA activity of > 0.66 nmol × mg^-1 × hr^-1 was only observed in more attenuated patients. Patients with an intermediate IDUA activity could be further classified by the presence of differentiating clinical characteristics, resulting in a model with 100% sensitivity and specificity for this cohort of patients.

Conclusion

Using genetic, biochemical and clinical characteristics, all potentially available in the newborn period, an algorithm was developed to predict the MPS I phenotype, allowing timely initiation of the optimal treatment strategy after introduction of NBS.

Small atrial septal defect associated with heart failure in an infant with a marginal left ventricle

Atrial septal defect (ASD) is usually asymptomatic in infancy, unless pulmonary hypertension or severe co-morbidity is present. We report a case of a 4-week-old infant with moderate-sized ASD, small patent ductus arteriosus (PDA), and a borderline sized left ventricle that developed heart failure. Despite the relatively small diameter of the ASD, this defect influenced the mechanism of heart failure significantly. After surgical closure of both PDA and ASD, the signs of pulmonary hypertension resolved and the patient developed a normal sized left ventricle. This report illustrates that the presence of a small ASD in combination with a marginal left ventricle may result in inadequate left ventricular filling, pulmonary hypertension and heart failure.

Lactobacillus johnsonii N6.2 stimulates the innate immune response through Toll-like receptor 9 in Caco-2 cells and increases intestinal crypt Paneth cell number in biobreeding diabetes-prone rats

Lactobacillus johnsonii (Ljo) N6.2 has been shown to mitigate the development of type 1 diabetes when administered to diabetes-prone rats. The specific mechanisms underlying this observed response remain under investigation. The objective of this study was to assess the effect of Ljo N6.2 on mucosal inflammatory response using differentiated Caco-2 monolayers. The mRNA expression levels of CCL20, CXCL8, and CXCL10 chemokines were determined by qRT-PCR. Ljo at 10(11) CFU/L induced a strong response in all chemokines examined. To assess the specific host-signaling pathways involved, we performed RT-PCR amplification of Toll-like receptors (TLR) and nucleotide-binding oligomerization domain-like receptors. TLR7 and TLR9 expression levels were induced 4.2- and 9-fold, respectively, whereas other TLR and nucleotide-binding oligomerization domain receptors were not modified. A similar effect was observed in Caco-2 monolayers treated with Ljo cell-free extract or purified nucleic acids (NA). Increased levels of IFN type 1 and IFN regulators Stat1 and IRF7 followed the upregulation of TLR9. Activation of TLR9 was also evidenced by increased Frizzled 5 expression in Ljo-treated Caco-2 cells and an increase in the number of Paneth cells in Ljo-fed, diabetes-prone rats. These results are in agreement with the polarizing-tolerizing mechanism recently described in which the apical stimulation of TLR9 in intestinal epithelial cells leads to a higher state of immunologic alertness. Furthermore, these results suggest that live probiotics could be, in the future, replaced with select cellular components.

Ischemia-reperfusion and neonatal intestinal injury

We review research relating ischemia/reperfusion to injury in the neonatal intestine. Epidemiologic evidence suggests that the most common form of necrotizing enterocolitis is not triggered by a primary hypoxic-ischemic event. Its late occurrence, lack of preceding ischemic events, and evidence for microbial and inflammatory processes preclude a major role for primary hypoxic ischemia as the sentinel pathogenic event. However, term infants, especially those with congenital heart disease who have development of intestinal necrosis, and those preterm infants with spontaneous intestinal perforations, are more likely to have intestinal ischemia as a primary component of their disease pathogenesis.

The intestinal microbiome: relationship to type 1 diabetes

This article discusses recent evidence that associates the developing intestinal microbiome to the pathogenesis of autoimmune T1D. It attempts to identify avenues that should be pursued that relate this new evidence to interventions that eventually could result in prevention.

Pulmonary effects of red blood cell transfusion in critically ill, non-bleeding patients

The aim of the study is to evaluate the effects of red blood cell (RBC) transfusions on pulmonary parameters in critically ill, non-bleeding patients. Retrospective chart analysis was performed on critically ill patients without overt bleeding in the intensive care unit (ICU) of a university hospital. In 83 patients in a 5-month period, who had received at least 1 RBC unit and stayed at least 24 h in the ICU, 199 transfusions of median 2 RBCs per transfusion (n = 504) were studied. Pulmonary parameters were retrieved during the period between 24 h before the start of transfusion and 24-48 h after transfusion. Outcome was assessed. The P(a)O(2)/F(I)O(2) dose-dependently decreased from 250 +/- 105 at baseline to 240 +/- 102 mmHg at 24 h after RBC transfusion (P = 0.003), irrespective of acute lung injury at baseline and RBC storage time. The lung injury score (LIS) also increased dose-dependently, whereas, at 48 h, oxygenation and LIS largely returned to baseline. For every seven RBCs transfused, the LIS transiently increased by 1 unit. There were no changes in haemodynamics, lung mechanics or chest radiography. The total number of RBCs given in the ICU did not directly contribute to ICU and 1-year mortality prediction. Transfusion of RBCs decreases oxygenation thereby increasing the LIS, dose-dependently and transiently, in a heterogeneous population of critically ill, non-bleeding patients, independent of prior cardiorespiratory status and RBC storage time. The effects are subtle, may go unseen and unreported and may represent subclinical transfusion-related acute lung injury. They do not adversely affect outcome, even at 1-year follow-up.