Association between adeno-associated virus 2 and severe acute hepatitis of unknown etiology in Japanese children.

INTRODUCTION: Outbreaks of acute hepatitis of unknown etiology (AHUE) in children were reported in Western countries in 2022. Previous studies found that adeno-associated virus 2 (AAV2) and its helper viruses, such as human adenovirus (HAdV) and human herpesvirus-6 (HHV-6), are frequently detected in patients with AHUE. However, the existence of hepatitis associated with AAV2 prior to AHUE outbreaks in 2022 had not yet been investigated. We aimed to investigate the association between AAV2 and pediatric acute hepatitis in Japanese children, as well as the incidence of AAV2-related hepatitis prior to 2022. METHODS: Preserved blood samples obtained from 49 pediatric patients with acute hepatitis between 2017 and 2023 were retrospectively analyzed. Blood samples from 50 children with acute illnesses and 50 children with chronic conditions were used as controls. Viral DNA loads were quantitated using real-time PCR. RESULTS: AAV2 DNA was detected in 12 % (6/49) of acute hepatitis cases but in only one acute illness and none of the chronic-condition control cases. The concentration of AAV2 DNA in the six acute hepatitis cases was higher than that in the acute-illness control case. Co-infection with one or more helper viruses, including HAdV, HHV-6, cytomegalovirus, and Epstein-Barr virus, was observed in five AAV2-positive cases. CONCLUSIONS: Our results indicated the sporadic occurrence of pediatric severe hepatitis associated with AAV2 infection in Japan prior to the AHUE outbreaks in 2022. Our findings suggest that co-infection with AAV2 and helper viruses plays a role in developing severe hepatitis.

Importance of HBsAg recognition by HLA molecules as revealed by responsiveness to different hepatitis B vaccines.

Hepatitis B (HB) vaccines (Heptavax-II and Bimmugen) designed based on HBV genotypes A and C are mainly used for vaccination against HB in Japan. To determine whether there are differences in the genetic background associated with vaccine responsiveness, genome-wide association studies were performed on 555 Heptavax-II and 1193 Bimmugen recipients. Further HLA imputation and detailed analysis of the association with HLA genes showed that two haplotypes, DRB1*13:02-DQB1*06:04 and DRB1*04:05-DQB1*04:01, were significantly associated in comparison with high-responders (HBsAb > 100 mIU/mL) for the two HB vaccines. In particular, HLA-DRB1*13:02-DQB1*06:04 haplotype is of great interest in the sense that it could only be detected by direct analysis of the high-responders in vaccination with Heptavax-II or Bimmugen. Compared with healthy controls, DRB1*13:02-DQB1*06:04 was significantly less frequent in high-responders when vaccinated with Heptavax-II, indicating that high antibody titers were less likely to be obtained with Heptavax-II. As Bimmugen and Heptavax-II tended to have high and low vaccine responses to DRB1*13:02, 15 residues were found in the Heptavax-II-derived antigenic peptide predicted to have the most unstable HLA-peptide binding. Further functional analysis of selected hepatitis B patients with HLA haplotypes identified in this study is expected to lead to an understanding of the mechanisms underlying liver disease.

Utilization of a novel Sendai virus vector in ex vivo gene therapy for hemophilia A.

Sendai virus (SeV) vectors are being recognized as a superior tool for gene transfer. Here, we report the transfection efficacy of a novel, high-performance, replication-defective, and persistent Sendai virus (SeVdp) vector in cultured cells and in mice using a near-infrared fluorescent protein (iRFP)-mediated in vivo imaging system. The novel SeVdp vector established persistent infection, and strong expression of inserted genes was sustained indefinitely in vitro. Analysis of iRFP-expressing cells transplanted subcutaneously into NOG, nude, and ICR mice suggests that innate immunity was involved in the exclusion of the transplanted cells. We also evaluated the feasibility of this novel SeVdp vector for hemophilia A gene therapy. This system enabled insertion of full-length FVIII genes, and transduced cells secreted FVIII into the culture medium. Transient FVIII activity was detected in the plasma of mice after intraperitoneal transplantation of these FVIII-secreting cells. Further improvement in methods to evade immunity, such as simultaneous expression of immunomodulatory genes, would make this novel vector a very useful tool in regenerative medicine.

Hepatitis B Surface Antibody Titers at One and Two Years after Hepatitis B Virus Vaccination in Healthy Young Japanese Adults.

Objective Since healthcare providers face an increased risk of hepatitis B virus (HBV) infection because of their work, vaccination plays a critical role in preventing HBV transmission. However, the duration for which acquired HBV surface antibodies (anti-HBs) persist remains unknown. To evaluate the primary immunologic response to HBV vaccination and its persistence in healthy Japanese adolescents. Methods In total, 690 young adults underwent HBV vaccination with a three-dose schedule. The primary response was determined by the anti-HBs titers at 1-2 months after the final dosage. Subjects with anti-HBs titers of <10, 10-100, and >100 mIU/mL were classified as "non-responders," "low-responders," and "sufficient responders," respectively. Anti-HB titers were re-measured at 1 or 2 years after vaccination. Results First, 95.8% and 72.8% of the subjects had anti-HBs titers of >10 and >100 mIU/mL, respectively, as a primary response. The anti-HBs titers measured at 1 and 2 years after vaccination were significantly correlated with those of the primary response (1 year: r=0.893, p<0.0001; 2 years: r=0.902, p<0.001). Most subjects with a titer of >100 mIU/mL at the primary response maintained an anti-HBs titer of >10 mIU/mL [1 year after vaccination, 208/209 (99.5%); 2 years after vaccination, 72/81 (90.1%)]. However, in subjects with a primary response of 10-100 mIU/mL the anti-HBs titer frequently declined; 17/38 (44.7%) and 9/10 (90.0%) subjects had a titer of <10 mIU/mL at 1 and 2 years, respectively. Conclusion The primary response was associated with the anti-HBs titers at 1 and 2 years after vaccination, and the anti-HBs titers of 54.2% of the low responders were not maintained for 2 years, even if they were vaccinated as healthy young adults.

Establishment of immunity against Epstein-Barr virus infection in a patient with CHARGE/complete DiGeorge syndrome after peripheral blood lymphocyte transfusion.

CHARGE syndrome is a rare congenital malformation syndrome which may share symptoms with DiGeorge syndrome. Complete DiGeorge syndrome (cDGS) is a severe form of DiGeorge syndrome, characterized by a CD3+ T-cell count of <50/mm3 due to athymia, and is fatal without immunologic intervention. We performed peripheral blood lymphocyte transfusion (PBLT) from an HLA-identical sibling without pretransplant conditioning in a CHARGE/cDGS patient with a novel CHD7 splice site mutation. Cyclosporine and short-term methotrexate were used for graft versus host disease (GVHD) prophylaxis, and neither acute nor chronic GVHD was observed. After PBLT, T-cell proliferative response to phytohemagglutinin and concanavalin A recovered, and intractable diarrhea improved. EBV infection, evidenced by a gradual increase in the viral genome copy number to a maximum of 2861 copies/µgDNA on day 42 after PBLT, resolved spontaneously. HLA A2402 restricted, EBV-specific CTLs were detected from peripheral blood on day 148, and EBV seroconversion was observed on day 181. Thus, EBV-specific immunity was successfully established by PBLT. Our results indicate that PBLT is a simple and effective therapy to reconstitute immune systems in CHARGE/DiGeorge syndrome.

Schuurs-Hoeijmakers syndrome in two patients from Japan.

Schuurs-Hoeijmakers syndrome is a rare disease characterized by intellectual disability and dysmorphic facial features among various physical abnormalities due to PACS1 mutation. To date, 28 patients with a recurrent de novo PACS1 mutation (c.607C > T) have been reported, primarily in Western populations. Here, we describe two Japanese patients with Schuurs-Hoeijmakers syndrome with a recurrent PACS1 mutation. In addition to the typical clinical symptoms, each patient presented novel clinical phenotypes. One patient presented with involuntary movements and was treated with trihexyphenidyl hydrochloride. We hypothesized that the PACS1 mutation leads to an inherent dopaminergic insufficiency that underlies the developing symptoms along with the neurodevelopmental processes. The second patient was diagnosed with lipomyelomeningocele during an examination for severe constipation at the age of 2 years and 8 months. The diagnosis of lipomyelomeningocele in this patient was delayed due to the lack of cutaneous lesions. As the majority of patients with PACS1 mutation present constipation, underdiagnosis of lipomyelomeningocele is a possibility. As the phenotypic expansion of the patients with Schuurs-Hoeijmakers syndrome was not fully recognized, additional studies are needed to clarify the clinical spectrum.

Interinstitutional patient transfers between rapid chemotherapy cycles were feasible to utilize proton beam therapy for pediatric Ewing sarcoma family of tumors.

AIM: To assess the feasibility of transferring to the University of Tsukuba Hospital for proton beam therapy (PBT) during intensive chemotherapy in children with Ewing sarcoma family of tumors (ESFT) who had been diagnosed and started their first-line treatment at prefectural or regional centers for pediatric oncology. BACKGROUND: The treatment of ESFT relies on a multidisciplinary approach using intensive neoadjuvant and adjuvant chemotherapies with surgery and radiotherapy. Multi-agent chemotherapy comprising vincristine, doxorubicin, cyclophosphamide, ifosfamide, and etoposide (VDC-IE) is widely used for ESFT, and the interval between each course is very important for maintaining the intensity and effect of chemotherapy. MATERIALS AND METHODS: Clinical information of patients who received PBT and VDC-IE between April 2009 and May 2016 was collected retrospectively. The intervals between each course of VDC-IE and adverse events were assessed. RESULTS: Fifteen patients were evaluated. No delays in the intervals of chemotherapy due to transfer were observed. There were no adverse events caused during/just after transfer and no increases in adverse events. The estimated 4-year overall and event-free survival rates were 94.6% and 84.8%, respectively. DISCUSSION: Although the results of efficacy are preliminary, survival rates were comparable with past studies. More experience and follow-up are required to further assess the efficacy of PBT for patients with ESFT. CONCLUSION: Multidisciplinary therapy for children with ESFT involving transfer to our hospital for PBT during VDC-IE was feasible without treatment delay or an increase in adverse events.

Hospital-based care utilization of children with medical complexity in Japan.

BACKGROUND: Few studies have investigated the hospital-based care utilization of children with medical complexity (CMC) in Japan. This study examined the frequency and differences in hospital-based care utilization for CMC according to the level of medical complexity (moderate and severe). METHODS: Medical records of three pediatric tertiary hospitals in one prefecture were examined in 2014. We examined the number of outpatient visits and of admissions to the hospital for CMC in the 5 years after the introduction of home medical care. RESULTS: Of 92 CMC, 55 had medical complexity that was moderate (CMC-moderate) and 37 had medical complexity that was severe (CMC-severe). The number of CMC who had medical care introduced at home had increased year by year, especially that of CMC <2 years old; the number of older CMC (i.e. 7-17 years old) had also increased in 2010-2014. The median total outpatient visits was 20 (IQR, 13-29 visits) for CMC-moderate and 20 (IQR, 17-26 visits) for CMC-severe in the first year. CMC-severe had significantly longer length of admissions in the 5 years than CMC-moderate. The number of total visits and admissions during the subsequent 4 years (from the second to the fifth year) was slightly decreased compared with the first year, but this was not significantly different. CONCLUSIONS: CMC had high utilization of hospital-based care, and consistently utilized hospital-based care in the 5 years after the introduction of home medical care. Further study is needed to examine both hospital-based and home/community-based services use.

Clinical phenotype and molecular analysis of a homozygous ABCB11 mutation responsible for progressive infantile cholestasis.

The bile salt export pump (BSEP) plays an important role in biliary secretion. Mutations in ABCB11, the gene encoding BSEP, induce progressive familial intrahepatic cholestasis type 2 (PFIC2), which presents with severe jaundice and liver dysfunction. A less severe phenotype, called benign recurrent intrahepatic cholestasis type 2, is also known. About 200 missense mutations in ABCB11 have been reported. However, the phenotype-genotype correlation has not been clarified. Furthermore, the frequencies of ABCB11 mutations differ between Asian and European populations. We report a patient with PFIC2 carrying a homozygous ABCB11 mutation c.386G>A (p.C129Y) that is most frequently reported in Japan. The pathogenicity of BSEPC129Y has not been investigated. In this study, we performed the molecular analysis of this ABCB11 mutation using cells expressing BSEPC129Y. We found that trafficking of BSEPC129Y to the plasma membrane was impaired and that the expression of BSEPC129Y on the cell surface was significantly lower than that in the control. The amount of bile acids transported via BSEPC129Y was also significantly lower than that via BSEPWT. The transport activity of BSEPC129Y may be conserved because the amount of membrane BSEPC129Y corresponded to the uptake of taurocholate into membrane vesicles. In conclusion, we demonstrated that c.386G>A (p.C129Y) in ABCB11 was a causative mutation correlating with the phenotype of patients with PFIC2, impairment of biliary excretion from hepatocytes, and the absence of canalicular BSEP expression in liver histological assessments. Mutational analysis in ABCB11 could facilitate the elucidation of the molecular mechanisms underlying the development of intrahepatic cholestasis.

Key HLA-DRB1-DQB1 haplotypes and role of the BTNL2 gene for response to a hepatitis B vaccine.

Approximately 5-10% of individuals who are vaccinated with a hepatitis B (HB) vaccine designed based on the hepatitis B virus (HBV) genotype C fail to acquire protective levels of antibodies. Here, host genetic factors behind low immune response to this HB vaccine were investigated by a genome-wide association study (GWAS) and Human Leukocyte Antigen (HLA) association tests. The GWAS and HLA association tests were carried out using a total of 1,193 Japanese individuals including 107 low responders, 351 intermediate responders, and 735 high responders. Classical HLA class II alleles were statistically imputed using the genome-wide SNP typing data. The GWAS identified independent associations of HLA-DRB1-DQB1, HLA-DPB1 and BTNL2 genes with immune response to a HB vaccine designed based on the HBV genotype C. Five HLA-DRB1-DQB1 haplotypes and two DPB1 alleles showed significant associations with response to the HB vaccine in a comparison of three groups of 1,193 HB vaccinated individuals. When frequencies of DRB1-DQB1 haplotypes and DPB1 alleles were compared between low immune responders and HBV patients, significant associations were identified for three DRB1-DQB1 haplotypes, and no association was identified for any of the DPB1 alleles. In contrast, no association was identified for DRB1-DQB1 haplotypes and DPB1 alleles in a comparison between high immune responders and healthy individuals. Conclusion: The findings in this study clearly show the importance of HLA-DR-DQ (i.e., recognition of a vaccine related HB surface antigen (HBsAg) by specific DR-DQ haplotypes) and BTNL2 molecules (i.e., high immune response to HB vaccine) for response to a HB vaccine designed based on the HBV genotype C. (Hepatology 2018).

Association of Japanese cedar pollinosis and sensitization with HLA-DPB1 in the Japanese adolescent.

BACKGROUND: Allergic rhinitis (AR) is a heterogeneous disorder that significantly affects daily activity, work productivity, sleep, learning, and quality of life in all generations. Japanese cedar (JC) pollen is the most common allergen responsible for the development of AR in Japan. AR caused by JC pollen is considered to be a multifactorial inheritance disease that is caused by both environmental and genetic factors. The aim of this study was to investigate whether Human Leukocyte Antigen-DPB1 (HLA-DPB1) is associated with JC sensitization/pollinosis. METHODS: Subjects in the present study were 544 students at the University of Tsukuba from 2013 to 2015. PCR-SSOP was performed to determine each individual's HLA-DPB1 alleles. Logistic regression analysis was performed to examine relationships between JC-related phenotypes and alleles/amino acid polymorphisms of HLA-DPB1. RESULTS: HLA-DPB1*02 allele were significantly associated with both JC sensitization/pollinosis (q < 0.05). Furthermore, HLA-DPB1*02:01 and HLA-DPB1*02:02 had a protective tendency for JC sensitization/pollinosis, and HLA-DPB1*05:01 had a susceptible tendency for sensitization (P < 0.05). In amino acid polymorphism analyses, Glutamic acid in position 69, Glycine-Glycine-Proline-Methionine in positions 84-87, Threonine in position 170 and Methionine in position 205 were also observed to have a protective tendency for JC sensitization (P < 0.05). Amino acid positions 69 and 84-87 were located in binding pocket 5 and 1 of HLA-DPß1, respectively. CONCLUSIONS: Amino acid changes in the allergen-binding pocket of HLA-DPß1 are likely to influence pollinosis/sensitization to the allergenic peptide of JC pollen and determine the pollinosis risk for each individual exposed to JC pollen.

Preaxial polydactyly in an individual with Wiedemann-Steiner syndrome caused by a novel nonsense mutation in KMT2A.

Wiedemann-Steiner syndrome (WDSTS) is an autosomal dominant disorder characterized by hypertrichosis, intellectual disability, and dysmorphic facial appearances (down-slanted vertically narrow palpebral fissures, wide nasal bridge, broad nasal tip, and thick eyebrows). In 2012, Jones and co-workers identified heterozygous mutations in KMT2A (lysine methyltransferase 2A) as the molecular cause of WDSTS. Although the phenotype of this syndrome continues to expand, the associated features are not fully understood. Here, we report WDSTS in a 12-year-old Japanese boy with a novel nonsense mutation in KMT2A. He had right preaxial polydactyly, which has not been previously reported in WDSTS. We could not identify a causal relationship between the KMT2A mutation and preaxial polydactyly, and cannot exclude the preaxial polydactyly is a simple coincidence. We summarized the clinical features of WDSTS associated with KMT2A mutation and discussed the cardinal symptoms in detail.

A novel BBS10 mutation identified in a patient with Bardet-Biedl syndrome with a violent emotional outbreak.

We report a 10-year-old girl with Bardet-Biedl syndrome caused by a novel mutation in the Bardet-Biedl syndrome 10 (BBS10) gene. She had multiple malformations, including a dysmorphic face, postaxial polydactyly, polycystic kidney and amblyopia. She presented with typical BBS features, including intellectual disability with emotional outbursts and mild obesity. Whole-exome sequencing identified compound heterozygous mutations with NM_024685.3:c.1677C>A [p.(Tyr559*)] and c.1974T>G [p.(Tyr658*)]. To our knowledge, the latter mutation has never been reported previously.

Human ESC/iPSC-Derived Hepatocyte-like Cells Achieve Zone-Specific Hepatic Properties by Modulation of WNT Signaling.

The function of hepatocytes largely depends on their position in the liver lobule. Although the method of differentiating hepatocytes from human pluripotent stem cells has been largely improved over the past decade, there remains no technique for generating hepatocyte-like cells (HLCs) with zone-specific hepatic properties. In this study, we searched for the factors that promote acquisition of zone-specific properties of HLCs. Here, we identified that WNT7B and WNT8B secreted from hepatocytes and cholangiocytes play important roles in achieving perivenous zone-specific characteristics, such as the enhancement of glutamine secretion, citric acid cycle, cytochrome P450 (CYP) 1A2 metabolism, and CYP1A2 induction capacities. We also found that WNT inhibitory factor (WIF-1) secreted from cholangiocytes was necessary for achieving periportal zone-specific characteristics, such as the enhancement of urea secretion and gluconeogenesis capacities. Therefore, WNT signal modulators secreted from hepatocytes or cholangiocytes conferred zone-specific hepatic properties onto HLCs.

Comorbidity and quality of life in childhood cancer survivors treated with proton beam therapy.

BACKGROUND: The rate of childhood cancer survival has recently reached >80%. Various adverse events among childhood cancer survivors (CCS) have been reported. Proton beams are able to avoid unnecessary irradiation to normal/vital organs. We conducted a quality of life (QOL) study for CCS who were treated with proton beam therapy (PBT). METHODS: We included those patients treated with PBT to the brain, head, or neck and who were ≤15 years old at the University of Tsukuba Hospital between 1983 and 2011. Clinical information was collected from medical records. Questionnaires including the Pediatric Quality of Life Inventory (PedsQL) 4.0 Generic Core Scales (which assess health-related quality of life) were sent to the families/patients. RESULTS: Sixty patients were included. Median age at treatment was 6.2 years. The number of patients with status alive/dead/unknown was 32/24/4. Median follow-up period was 63.0 months (range, 48-340 months) for survivors. Questionnaires were sent to 25 families/patients and 19 were returned. PedsQL was assessed for 17 patients. Eleven of 32 living patients had at least one comorbidity grade 3/4. Average QOL score was above that for Japanese schoolchildren and adolescents. There was no correlation with comorbidity, and only longer time from treatment was correlated with a higher PedsQL score (P = 0.006). CONCLUSION: CCS who were treated with multimodal treatment using PBT had a higher QOL score. Higher score was related to longer time since treatment, regardless of comorbidity.

Haploidentical peripheral blood stem cell transplantation without irradiation or busulfan after reduced-intensity conditioning for KMT2A(MLL)-rearranged infant B-cell precursor acute lymphoblastic leukemia: Report of two cases.

We present two infants with KMT2A(MLL)-gene-R-associated BCP-ALL, who received HLA haploidentical PBSCT after RIC. The patients developed ALL at age 6 months and 3 months, respectively. Case 1 underwent PBSCT at the second CR with detectable KMT2A-AFF1(MLL-AF4) fusion gene transcript at 11 months of age, and Case 2 at the first CR without KMT2A-MLLT1(MLL-ENL) fusion gene transcript at 8 months of age. Both patients received G-CSF-mobilized unmanipulated peripheral blood mononuclear cells from their HLA haploidentical mothers after administration of FLU, MEL, and ATG. Tacrolimus, methotrexate, and mPSL were administered as prophylaxis against GVHD. Engraftment was rapidly obtained with complete chimerism in both patients. Acute adverse events included acute GVHD in Case 1 and bacterial sepsis in Case 2. At last clinical check at age 5 years and 4 years, respectively, both patients were recurrence-free and attained normal growth and development. We conclude that PBSCT from an HLA haploidentical mother with non-TBI and non-BU regimen seems feasible and efficacious, offering favorable life quality for infants.

Generation of a bile salt export pump deficiency model using patient-specific induced pluripotent stem cell-derived hepatocyte-like cells.

Bile salt export pump (BSEP) plays an important role in hepatic secretion of bile acids and its deficiency results in severe cholestasis and liver failure. Mutation of the ABCB11 gene encoding BSEP induces BSEP deficiency and progressive familial intrahepatic cholestasis type 2 (PFIC2). Because liver transplantation remains standard treatment for PFIC2, the development of a novel therapeutic option is desired. However, a well reproducible model, which is essential for the new drug development for PFIC2, has not been established. Therefore, we attempted to establish a PFIC2 model by using iPSC technology. Human iPSCs were generated from patients with BSEP-deficiency (BD-iPSC), and were differentiated into hepatocyte-like cells (HLCs). In the BD-iPSC derived HLCs (BD-HLCs), BSEP was not expressed on the cell surface and the biliary excretion capacity was significantly impaired. We also identified a novel mutation in the 5'-untranslated region of the ABCB11 gene that led to aberrant RNA splicing in BD-HLCs. Furthermore, to evaluate the drug efficacy, BD-HLCs were treated with 4-phenylbutyrate (4PBA). The membrane BSEP expression level and the biliary excretion capacity in BD-HLCs were rescued by 4PBA treatment. In summary, we succeeded in establishing a PFIC2 model, which may be useful for its pathophysiological analysis and drug development.