Genetic Ablation of Pyruvate Dehydrogenase Kinase Isoform 4 Gene Enhances Recovery from Hyperoxic Lung Injury: Insights into Antioxidant and Inflammatory Mechanisms.

BACKGROUND: Pyruvate dehydrogenase kinase isoform 4 (PDK4) plays a pivotal role in the regulation of cellular proliferation and apoptosis. The objective of this study was to examine whether the genetic depletion of the PDK4 gene attenuates hyperoxia-induced lung injury in neonatal mice. METHODS: Neonatal PDK4-/- mice and wild-type (WT) mice were exposed to oxygen concentrations of 21% (normoxia) and 95% (hyperoxia) for the first 4 days of life. Pulmonary histological assessments were performed, and the mRNA levels of lung PDK4, monocyte chemoattractant protein (MCP)-1 and interleukin (IL)-6 were assessed. The levels of inflammatory cytokines in lung tissue were quantified. RESULTS: Following convalescence from neonatal hyperoxia, PDK4-/- mice exhibited improved lung alveolarization. Notably, PDK4-/- mice displayed significantly elevated MCP-1 protein levels in pulmonary tissues following 4 days of hyperoxic exposure, whereas WT mice showed increased IL-6 protein levels under similar conditions. Furthermore, neonatal PDK4-/- mice subjected to hyperoxia demonstrated markedly higher MCP-1 mRNA expression at 4 days of age compared to WT mice, while IL-6 mRNA expression remained unaffected in PDK4-/- mice. CONCLUSIONS: Newborn PDK4-/- mice exhibited notable recovery from hyperoxia-induced lung injury, suggesting the potential protective role of PDK4 depletion in mitigating lung damage.

Rare diseases presenting with hemophagocytic lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is a potentially fatal hyperinflammatory disorder characterized by hypercytokinemia caused by excessive activation of cytotoxic T cells and macrophages. HLH is caused by a variety of factors and is classified into primary and secondary HLH. Familial HLH (FHL) types 1-5, X-linked lymphoproliferative syndrome types 1 and 2, and FHL syndrome with hypopigmentation are all examples of primary HLH. Secondary HLH, on the other hand, is linked to infections, malignant tumors, autoimmune diseases, and other diseases. The causes of HLH vary, and finding the underlying disease is critical for diagnosis and treatment. The majority of HLH is caused by the aforementioned conditions; however, approximately 10% of cases are caused by rare diseases such as inborn errors of immunity (IEI) and inborn errors of metabolism (IEM). Novel IEI, such as RhoG, MAP kinase activating death domain, TIM3, and ZNFX1 deficiencies, have recently been identified as causes of HLH. IEM patients are rarely associated with HLH. Surprisingly, children with lysinuric protein intolerance and lysosomal acid lipase deficiency (Wolman disease) frequently develop HLH. This review focuses on the most recent knowledge of HLH caused by rare diseases such as IEI and IEM.

A Japanese Patient with Genitopatellar Syndrome Transiently Presenting with Cardiac Intramural Cavity during the Neonatal Period.

Genitopatellar syndrome (GPS) is a rare autosomal dominant disorder caused by de novo pathogenic variants in the KAT6B gene. It is characterized by genital abnormalities, patellar hypoplasia/agenesis, flexion contractures of the hips and knees, corpus callosum agenesis with microcephaly, and hydronephrosis and/or multiple renal cysts. More than half of patients with GPS have congenital heart defects, mostly atrial and/or ventricular septal defects, patent foramen ovale, and patent ductus arteriosus. We report a case of a Japanese neonate with a de novo heterozygous c.3769_3772delTCTA pathogenic variant in the KAT6B gene who presented with a cardiac intramural cavity of the ventricular septum at birth. The cavity unexpectedly disappeared at 1 month of age, but trabecular septal thinning and flash remained. The features of the cavity were not consistent with those of congenital ventricular diverticulum or aneurysm, and its identity and prognosis are still unclear. Because patients with GPS may exhibit various forms of cardiac malformation, careful cardiac examination and follow-up are required from birth in cases of suspected GPS.

An Early-Onset Neuronopathic Form of Acid Sphingomyelinase Deficiency: A SMPD1 p.C133Y Mutation in the Saposin Domain of Acid Sphingomyelinase.

Acid sphingomyelinase (ASM) is a lysosomal hydrolase that degrades sphingomyelin into ceramide and phosphocholine. Recent crystallographic studies revealed the functional role of the N-terminal ASM saposin domain. ASM deficiency due to mutations in the ASM-encoding sphingomyelin phosphodiesterase 1 (SMPD1) gene causes an autosomal recessive sphingolipid-storage disorder, known as Niemann-Pick disease Type A (NPA) or Type B (NPB). NPA is an early-onset neuronopathic disorder, while NPB is a late-onset non-neuronopathic disorder. A homozygous one-base substitution (c.398G>A) of the SMPD1 gene was identified in an infant with NPA, diagnosed with complete loss of ASM activity in the patient's fibroblasts. This mutation is predicted to substitute tyrosine for cysteine at amino acid residue 133, abbreviated as p.C133Y. The patient showed developmental delay, hepatosplenomegaly and rapid neurological deterioration leading to death at the age of 3 years. To characterize p.C133Y, which may disrupt one of the three disulfide bonds of the N-terminal ASM saposin domain, we performed immunoblotting analysis to explore the expression of a mutant ASM protein in the patient's fibroblasts, showing that the protein was detected as a 70-kDa protein, similar to the wild-type ASM protein. Furthermore, transient expression of p.C133Y ASM protein in COS-7 cells indicated complete loss of ASM enzyme activity, despite that the p.C133Y ASM protein was properly localized to the lysosomes. These results suggest that the proper three-dimensional structure of saposin domain may be essential for ASM catalytic activity. Thus, p.C133Y is associated with complete loss of ASM activity even with stable protein expression and proper subcellular localization.

A novel S269C mutation in fibroblast growth factor receptor 3 in a Japanese child with hypochondroplasia.

Functionally activating mutations in fibroblast growth factor receptor 3 (FGFR3) can cause four types of autosomal dominant skeletal dysplasia with short-limbed dwarfism that include the mildest phenotype, hypochondroplasia (HCH). A novel mutation (c.805A>T, p.S269C) was identified in a Japanese infant with HCH through direct sequencing of all FGFR3 exons and exon/intron boundaries. This mutation creates an additional cysteine residue in the extracellular region of FGFR3 that results in the functional activation of FGFR3.

Elevation of Serum Acid Sphingomyelinase Activity in Children with Acute Respiratory Syncytial Virus Bronchiolitis.

Acid sphingomyelinase (ASM) is a lysosomal enzyme that hydrolyzes sphingomyelin into ceramide, a bioactive lipid to regulate cellular physiological functions. Thus, ASM activation has been reported as a key event in pathophysiological reactions including inflammation, cytokine release, oxidative stress, and endothelial damage in human diseases. Since ASM activation is associated with extracellular ASM secretion through unknown mechanisms, it can be detected by recognizing the elevation of secretory ASM (S-ASM) activity. Serum S-ASM activity has been reported to increase in chronic diseases, acute cardiac diseases, and systemic inflammatory diseases. However, the serum S-ASM has not been investigated in common acute illness. This study was designed to evaluate serum S-ASM activity in children with common acute illness. Fifty children with common acute illness and five healthy children were included in this study. The patients were categorized into five groups based on clinical diagnoses: acute respiratory syncytial virus (RSV) bronchiolitis, adenovirus infection, streptococcal infection, asthma, and other infections due to unknown origin. The serum S-ASM activity was significantly elevated at 6.9 ± 1.6 nmol/0.1 mL/6 h in the group of acute RSV bronchiolitis patients compared with healthy children who had a mean level of 1.8 ± 0.8 nmol/0.1 mL/6 h (p < 0.05). In the other illness groups, the serum S-ASM activity was not significantly elevated. The results suggest an association of ASM activation with RSV infection, a cause for common acute illness. This is the first report to describe the elevation of serum S-ASM activity in respiratory tract infection.

Elevated Urinary Levels of 8-Hydroxy-2'-deoxyguanosine in a Japanese Child of Xeroderma Pigmentosum/Cockayne Syndrome Complex with Infantile Onset of Nephrotic Syndrome.

Nucleotide excision repair (NER) is an essential biological pathway protecting against ultraviolet light-induced DNA damage. Deficient NER causes a group of rare genetic disorders including two autosomal recessive diseases, xeroderma pigmentosum (XP) and Cockayne syndrome (CS). In addition to the cutaneous photosensitivity shared in XP and CS, CS is featured by growth failure, neurological deterioration, microcephaly, and deep sunken eyes. XP/CS complex is an extremely rare type of NER disorder with a distinct phenotype that is characterized by the skin and eye pathology of XP and the somatic and neurological abnormalities of CS. Some of CS cases have been reported to be complicated with renal failure, but the genetic background or the etiology of the renal failure has not been reported. We herein report a 1-year-old Japanese boy with XP/CS complex, complicated by nephrotic syndrome. Diagnosis was confirmed by the presence of compound heterozygous mutations, G47R (c.139G>A) and R616G (c.1846C>G), in the excision repair cross-complementation group 2 (ERCC2) gene. The kidney biopsies, performed at the age of 1 year and 2 months, revealed diffuse expansion of the mesangial matrix and segmental glomerulosclerosis under light microscopy, and diffused thin capillary walls with partially lamellated regions under electron microscopy. Notably, high levels of urinary 8-hydroxy-2'-deoxyguanosin, known as an oxidative stress marker, were observed during the clinical course. The patient died at the age of 1 year and 11 months because of renal failure. We suggest the involvement of oxidative stress in the pathogenesis of nephrotic syndrome in NER disorders.

Elevation of Serum Acid Sphingomyelinase Activity in Acute Kawasaki Disease.

Kawasaki disease (KD) is an acute systemic vasculitis that affects both small and medium-sized vessels including the coronary arteries in infants and children. Acid sphingomyelinase (ASM) is a lysosomal glycoprotein that hydrolyzes sphingomyelin to ceramide, a lipid, that functions as a second messenger in the regulation of cell functions. ASM activation has been implicated in numerous cellular stress responses and is associated with cellular ASM secretion, either through alternative trafficking of the ASM precursor protein or by means of an unidentified mechanism. Elevation of serum ASM activity has been described in several human diseases, suggesting that patients with diseases involving vascular endothelial cells may exhibit a preferential elevation of serum ASM activity. As acute KD is characterized by systemic vasculitis that could affect vascular endothelial cells, the elevation of serum ASM activity should be considered in these patients. In the present study, serum ASM activity in the sera of 15 patients with acute KD was determined both before and after treatment with infusion of high-dose intravenous immunoglobulin (IVIG), a first-line treatment for acute KD. Serum ASM activity before IVIG was significantly elevated in KD patients when compared to the control group (3.85 ± 1.46 nmol/0.1 ml/6 h vs. 1.15 ± 0.10 nmol/0.1 ml/6 h, p < 0.001), suggesting that ASM activation may be involved in the pathophysiology of this condition. Serum ASM activity before IVIG was significantly correlated with levels of C-reactive protein (p < 0.05). These results suggest the involvement of sphingolipid metabolism in the pathophysiology of KD.

Novel mutation in the TMPRSS6 gene with iron-refractory iron deficiency anemia.

Iron-refractory iron deficiency anemia (IRIDA) is a rare autosomal recessive disease characterized by congenital hypochromic microcytic anemia, low transferrin saturation, low serum iron, normal-high serum ferritin, and increased hepcidin. This disease is caused by loss-of-function mutations in TMPRSS6 that lead to high hepcidin and result in severe anemia. We report our experience with an 11-year-old Japanese girl with hypochromic microcytic anemia, low serum iron, and high serum ferritin, with anemia that was refractory to the oral iron that was prescribed frequently from early childhood. Presence of high hepcidin suggested a diagnosis of IRIDA, which was eventually confirmed by identification of a novel homozygous mutation, p.Pro354Leu, in the TMPRSS6 gene. This case suggests that serum hepcidin should be routinely measured for differential diagnosis when patients with IDA are unresponsive to oral iron or have unusual clinical features.

Pathological fracture of the femur in Alagille syndrome that was treated with low-intensity pulsed ultrasound stimulation and an Ilizarov ring fixator: a case report.

BACKGROUND: Alagille syndrome is a multisystem disorder, which is characterized by hypoplasia of the intrahepatic bile ducts, malformations of the cardiovascular system, eyes, and vertebral column, and abnormal facies. Several of the characteristics of Alagille syndrome may result in an especially high risk of fracture. The majority of patients suffer from chronic cholestasis, which can have a variety of adverse effects on bone metabolism. In Alagille syndrome, fractures primarily occur in the lower limb long bones in the absence of significant trauma. CASE PRESENTATION: A 9-year-old Japanese girl with Alagille syndrome was admitted to our institution with marked hyperbilirubinemia and a pathological fracture of the femur. She had been diagnosed with biliary atresia at the age of 1 month and treated with surgical bile duct reconstruction, vitamins D and K, and ursodeoxycholic acid. However, her liver dysfunction and hyperbilirubinemia worsened. The pathological fracture of the femur was treated with low-intensity pulsed ultrasound stimulation (LIPUS) and an Ilizarov ring fixator. Seventy-four days after surgery, the patient had anatomically and functionally recovered. There was no leg-length discrepancy and no angular malalignment of the lower extremities as measured clinically and radiographically. The range of motion of the hip, knee, and ankle of the patient's operative leg matched the range of motion in the nonoperative leg. CONCLUSION: To the best of our knowledge, there are no reports on use of the Ilizarov frame and LIPUS in diaphyseal femoral fractures in Alagille syndrome. This case report provides evidence that this procedure is successful for managing such diaphyseal fractures in Alagille syndrome.

Fatigue and quality of life in citrin deficiency during adaptation and compensation stage.

Citrin-deficient children and adolescents between adult-onset type II citrullinemia and neonatal intrahepatic cholestasis by citrin deficiency do not have clear clinical features except for unusual diet of high-fat, high-protein, and low-carbohydrate food. The aims of the present study are to characterize fatigue and quality of life (QOL) in citrin-deficient patients during adaptation and compensation stage, and to define the relationship between fatigue and QOL. The study subjects were 55 citrin-deficient patients aged 1-22years (29 males) and 54 guardians. Fatigue was evaluated by self-reports and proxy-reports of the PedsQL Multidimensional Fatigue Scale. QOL was evaluated by the PedsQL Generic Core Scales. Both scale scores were significantly lower in child self-reports (p<0.01 and p<0.05, respectively) and parent proxy-reports (p<0.01 and p<0.01, respectively) than those of healthy children. Citrin-deficient patients with scores of 50 percentile or less of healthy children constituted 67.5% of the sample for the Fatigue Scale and 68.4% for the Generic Core Scales. The PedsQL Fatigue Scale correlated with the Generic Core Scales for both the patients (r=0.56) and parents reports (r=0.71). Assessments by the patients and their parents showed moderate agreement. Parents assessed the condition of children more favorably than their children. The study identified severe fatigue and impaired QOL in citrin-deficient patients during the silent period, and that such children perceive worse fatigue and poorer QOL than those estimated by their parents. The results stress the need for active involvement of parents and medical staff in the management of citrin-deficient patients during the silent period.

Congenital hyperinsulinism in an infant with paternal uniparental disomy on chromosome 11p15: few clinical features suggestive of Beckwith-Wiedemann syndrome.

Beckwith-Wiedemann syndrome (BWS) is the most common congenital overgrowth syndrome involving tumor predisposition. BWS is caused by various epigenetic or genetic alterations that disrupt the imprinted genes on chromosome 11p15.5 and the clinical findings of BWS are highly variable. Hyperinsulinemic hypoglycemia is reported in about half of all babies with BWS. We identified an infant with diazoxide-unresponsive congenital hyperinsulinism (HI) without any apparent clinical features suggestive of BWS, but diagnosed BWS by molecular testing. The patient developed severe hyperinsulinemic hypoglycemia within a few hours after birth, with macrosomia and mild hydronephrosis. We excluded mutations in the K(ATP) channel genes on chromosome 11p15.1, but found a rare homozygous single nucleotide polymorphism (SNP) of ABCC8. Parental SNP pattern suggested paternal uniparetal disomy in this region. By microsatellite marker analysis on chromosome 11p15, we could diagnose BWS due to the mosaic of paternal uniparental disomy. Our case suggests that some HI of unknown genetic etiology could involve undiagnosed BWS with no apparent clinical features, which might be diagnosed only by molecular testing.

A case report of pediatric fulminant hepatitis treated with plasma diafiltration.

Plasma diafiltration (PDF) is blood purification therapy in which simple plasma exchange is performed with a membrane plasma separator while dialysate flows outside the hollow fibers. A 14-year-old boy with fulminant hepatitis underwent two sessions of PDF and one session of hemodiafiltration. We infused filtered replacement fluid for artificial kidneys at a dialysate flow rate of 600 mL/h and a replacement flow rate of 450 mL/h. We infused fresh frozen plasma (1200 mL) and 25% albumin solution (50 mL) intravenously over 8 h. Each PDF session lasted 8 h. The patient's total bilirubin, interleukin-18, and cystatin C levels decreased with treatment, and he recovered from hepatic failure. PDF may be an extremely useful blood purification therapy for pediatric fulminant hepatitis in terms of both medical economics and cytokine removal.

Split notochord syndrome: ileal duplication causing intermittent episodes of vomiting.

Split notochord syndrome is a group of developmental abnormalities caused by abnormal splitting or deviation of the notochord, clinically resulting in the duplicated bowel associated with vertebral anomalies. In this syndrome, initial presentations due to duplicated bowel, vomiting, abdominal pain, and failure to thrive, usually occur before 1 year of age. We here report a 12-year-old boy with intermittent vomiting, previously diagnosed with cyclic vomiting syndrome. On abdominal x-ray examination, a defect in the closure of posterior vertebral arches was observed in the 5th lumbar vertebral body, indicating the complication of spina bifida occulta. This finding suggested the diagnosis of split notochord syndrome. A magnetic resonance imaging study revealed a cystic mass lesion in the pelvic cavity. (99m)Tc-pertechnetate scintigraphy, which is frequently used to detect ectopic gastric mucosa for the diagnosis of Meckel's diverticulum, showed a positive spot corresponding to the cystic mass lesion. Surgical resection of the cystic mass lesion demonstrated ileal duplication with ectopic gastric mucosa. Surgical findings suggest that symptoms of the patient were due to ulceration, inflammation, or bleeding caused by acid-peptic juice secreted from ectopic gastric mucosa. Duplication of the alimentary tract should be considered as a possible cause in patients with symptoms suggesting cyclic vomiting syndrome.