Environmental Toxin Biliatresone-Induced Biliary Atresia-like Abnormal Cilia and Bile Duct Cell Development of Human Liver Organoids.

Biliary atresia (BA) is a poorly understood and devastating obstructive bile duct disease of newborns. Biliatresone, a plant toxin, causes BA-like syndrome in some animals, but its relevance in humans is unknown. To validate the hypothesis that biliatresone exposure is a plausible BA disease mechanism in humans, we treated normal human liver organoids with biliatresone and addressed its adverse effects on organoid development, functions and cellular organization. The control organoids (without biliatresone) were well expanded and much bigger than biliatresone-treated organoids. Expression of the cholangiocyte marker CK19 was reduced, while the hepatocyte marker HFN4A was significantly elevated in biliatresone-treated organoids. ZO-1 (a tight junction marker) immunoreactivity was localized at the apical intercellular junctions in control organoids, while it was markedly reduced in biliatresone-treated organoids. Cytoskeleton F-actin was localized at the apical surface of the control organoids, but it was ectopically expressed at the apical and basal sides in biliatresone-treated organoids. Cholangiocytes of control organoids possess primary cilia and elicit cilia mechanosensory function. The number of ciliated cholangiocytes was reduced, and cilia mechanosensory function was hampered in biliatresone-treated organoids. In conclusion, biliatresone induces morphological and developmental changes in human liver organoids resembling those of our previously reported BA organoids, suggesting that environmental toxins could contribute to BA pathogenesis.

A systematic review and meta-analysis of the effects of long-term antibiotic use on cognitive outcomes.

Antibiotics are indispensable to infection management. However, use of antibiotics can cause gut microbiota dysbiosis, which has been linked to cognitive impairment by disrupting communication between the gut microbiota and the brain. We conducted a systematic review and meta-analysis on the effects of long-term antibiotic use on cognitive outcomes. We have searched PubMed, Web of Science, Embase, Cochrane Library and Scopus for English publications before March 2023 following the PRISMA guidelines. Screening, data extraction, and quality assessment were performed in duplicate. 960 articles were screened and 16 studies which evaluated the effect of any antibiotic compared to no antibiotics or placebo were included. Case-reports, in vitro and animal studies were excluded. We found that antibiotic use was associated with worse cognitive outcomes with a pooled effect estimate of - 0.11 (95% CI - 0.15, - 0.07, Z = 5.45; P < 0.00001). Subgroup analyses performed on adult vs pediatric patients showed a similar association of antibiotic on cognition in both subgroups. Antibiotic treatment was not associated with worse cognition on subjects with existing cognitive impairment. On the other hand, antibiotic treatment on subjects with no prior cognitive impairment was associated with worse cognitive performance later in life. This calls for future well-designed and well-powered studies to investigate the impact of antibiotics on cognitive performance.

QTc interval prolongation independently associates with FGF23 and predicts mortality in predialysis CKD.

INTRODUCTION: QTc interval prolongation is increasingly frequent as CKD advances and predicts death in dialysis. However, predictors and mortality-risk in predialysis CKD are understudied. FGF23 induces left ventricular hypertrophy (LVH) which is associated with QTc interval prolongation and death, suggesting a possible pathway from FGF23 to death that entails LVH and QTc prolongation. We looked for links between FGF23 and prolonged QTc intervals mediated by LVH, and for deaths associated with QTc prolongation in a prospective observational cohort of patients with predialysis CKD. METHODS: Participants underwent protocolized baseline and semi-annual FGF23 testing, baseline and study end echocardiograms, and baseline and annual electrocardiograms over three years. RESULTS: 2,254 participants (34.1% female; mean age 68.7 years; mean glomerular filtration rate 41.4 ml/min/m2) enrolled. Baseline LVH (left ventricular mass index >131 g/m2 (>100 g/m2 if female)) was present in 10.8% and prolonged QTc intervals (>=500 ms) in 1.5%. One hundred thirty-eight (6.1%) participants died during the study. In generalized mixed effects regression, each unit increase in the natural log of FGF23 - but not LVH - predicted an odds ratio of 1.76 (1.15, 2.70, p=0.009) for prolonged QTc intervals independently of 15 other covariates. Mediation analysis showed that only 13% of FGF23's total effect on prolonged QTc intervals was mediated by LVH. Patients with prolonged QTc intervals had higher unadjusted (log rank p<0.001) and adjusted (hazard ratio 3.15 (1.38, 7.16, p=0.006)) mortality rates than those with QTc intervals <500 ms. CONCLUSIONS: QTc interval prolongation ≥500 ms was prospectively associated with FGF23 independently of LVH, and with a tripling of mortality-risk in patients with predialysis CKD.

BNT162b2 versus mRNA-1273 Third Dose COVID-19 Vaccine in Patients with CKD and Maintenance Dialysis Patients.

BACKGROUND: There is a lack of randomized controlled trial data regarding differences in immunogenicity of varying coronavirus disease 2019 (COVID-19) mRNA vaccine regimens in CKD populations. METHODS: We conducted a randomized controlled trial at three kidney centers in Toronto, Ontario, Canada, evaluating the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody response after third dose vaccination. Participants ( n =273) with CKD not on dialysis or receiving dialysis were randomized 1:1 to third dose 30- µ g BNT162b2 (Pfizer-BioNTech) or 100- µ g mRNA-1273 (Moderna). The primary outcome of this study was SARS-CoV-2 IgG-binding antibodies to the receptor-binding domain (anti-RBD). Spike protein (antispike), nucleocapsid protein, and vaccine reactogenicity were also evaluated. Serology was measured before third dose and 1, 3, and 6 months after third dose. A subset of participants ( n =100) were randomly selected to assess viral pseudovirus neutralization against wild-type D614G, B.1.617.2 (Delta), and B.1.1.529 (Omicron BA.1). RESULTS: Among 273 participants randomized, 94% were receiving maintenance dialysis and 59% received BNT162b2 for initial two dose COVID-19 vaccination. Third dose of mRNA-1273 was associated with higher mean anti-RBD levels (1871 binding antibody units [BAU]/ml; 95% confidence interval [CI], 829 to 2988) over a 6-month period in comparison with third dose BNT162b2 (1332 BAU/ml; 95% CI, 367 to 2402) with a difference of 539 BAU/ml (95% CI, 139 to 910; P = 0.009). Neither antispike levels nor neutralizing antibodies to wild-type, Delta, and Omicron BA.1 pseudoviruses were statistically different. COVID-19 infection occurred in 10% of participants: 15 (11%) receiving mRNA-1273 and 11 (8%) receiving BNT162b2. Third dose BNT162b2 was not associated with a significant different risk for COVID-19 in comparison with mRNA-1273 (hazard ratio, 0.78; 95% CI, 0.27 to 2.2; P = 0.63). CONCLUSIONS: In patients with CKD, third dose COVID-19 mRNA vaccination with mRNA-1273 elicited higher SARS-CoV-2 anti-RBD levels in comparison with BNT162b2 over a 6-month period. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER: COVID-19 Vaccine Boosters in Patients With CKD (BOOST KIDNEY), NCT05022329 .

Artificial intelligence-based approaches for the detection and prioritization of genomic mutations in congenital surgical diseases.

Genetic mutations are critical factors leading to congenital surgical diseases and can be identified through genomic analysis. Early and accurate identification of genetic mutations underlying these conditions is vital for clinical diagnosis and effective treatment. In recent years, artificial intelligence (AI) has been widely applied for analyzing genomic data in various clinical settings, including congenital surgical diseases. This review paper summarizes current state-of-the-art AI-based approaches used in genomic analysis and highlighted some successful applications that deepen our understanding of the etiology of several congenital surgical diseases. We focus on the AI methods designed for the detection of different variant types and the prioritization of deleterious variants located in different genomic regions, aiming to uncover susceptibility genomic mutations contributed to congenital surgical disorders.

The Current Proceedings of PSC-Based Liver Fibrosis Therapy.

Liver fibrosis was initially considered to be an irreversible process which will eventually lead to the occurrence of liver cancer. So far there has been no effective therapeutic approach to treat liver fibrosis although scientists have put tremendous efforts into the underlying mechanisms of this disease. Therefore, in-depth research on novel and safe treatments of liver fibrosis is of great significance to human health. Pluripotent stem cells (PSCs) play important roles in the study of liver fibrosis due to their unique features in self-renewal ability, pluripotency, and paracrine function. This article mainly reviews the applications of PSCs in the study of liver fibrosis in recent years. We discuss the role of PSC-derived liver organoids in the study of liver fibrosis, and the latest research advances on the differentiation of PSCs into hepatocytes or macrophages. We also highlight the importance of exosomes of PSCs for the treatment of liver fibrosis.

Amyloidoses in Onco-Nephrology Practice: A Multidisciplinary Case-Based Conference Report.

Introduction and Objective: Amyloidoses are a heterogeneous group of disorders resulting from deposition of amyloid fibrils into extracellular tissues. While the kidneys are one of the most frequent sites of amyloid deposition, amyloid deposits can also affect a wide range of organ systems, including the heart, liver, gastrointestinal tract, and peripheral nerves. The prognosis of amyloidosis, especially with cardiac involvement, remains poor; however, a collaborative approach applying new tools for diagnosis and management may improve outcomes. In September 2021, the Canadian Onco-Nephrology Interest Group hosted a symposium to discuss diagnostic challenges and recent advances in the management of amyloidosis from the perspectives of the nephrologist, cardiologist, and onco-hematologist. Methods and Sources of Information: Through structured presentations, the group discussed a series of cases highlighting the varied clinical presentations of amyloidoses affecting the kidney and heart. Expert opinions, clinical trial findings, and publication summaries were used to illustrate patient-related and treatment-related considerations in the diagnosis and management of amyloidoses. Key findings: (1) Overview of the clinical presentation of amyloidoses and the role of specialists in performing timely and accurate diagnostic workup; (2) review of best practices for multidisciplinary management of amyloidosis, including prognostic variables and determinants of treatment response; and (3) update on new and emerging treatments in the management of light chain and amyloid transthyretin amyloidoses. Limitations: This conference featured multidisciplinary discussion of cases, and learning points reflect the assessments by the involved experts/authors. Implications: Identification and management of amyloidoses can be facilitated with a multidisciplinary approach and higher index of suspicion from cardiologists, nephrologists, and hemato-oncologists. Increased awareness of clinical presentations and diagnostic algorithms for amyloidosis subtyping will lead to more timely interventions and improved clinical outcomes.

Introduction et objectifs: Les amyloïdoses sont un groupe hétérogène de troubles résultant du dépôt de fibrilles amyloïdes dans les tissus extracellulaires. Les reins sont un des sites les plus fréquents de dépôts amyloïdes, mais ces derniers peuvent également affecter un large éventail de systèmes et d'organes, notamment le cœur, le foie, le tractus gastro-intestinal et les nerfs périphériques. Le pronostic de l'amyloïdose, en particulier en cas d'atteinte cardiaque, est mauvais. Les résultats peuvent cependant être améliorés par une approche collaborative utilisant de nouveaux outils de diagnostic et de prise en charge. En septembre 2021, le Canadian Onco-Nephrology Interest Group (groupe canadien d'intérêt en onco-néphrologie) a organisé un symposium pour discuter des défis liés au diagnostic de l'amyloïdose et des récents progrès dans la gestion de cette maladie du point de vue du néphrologue, du cardiologue et de l'hémato-oncologue. Méthodologie et sources de l'information: Au moyen de présentations structurées, le groupe a discuté d'une série de cas mettant en évidence les diverses présentations cliniques d'amyloïdoses affectant les reins et le cœur. Les opinions d'experts, les résultats des essais cliniques et les résumés des publications ont été utilisés pour illustrer les facteurs liés au patient et au traitement à considérer dans le diagnostic et la prise en charge des amyloïdoses. Principaux résultats: 1) Aperçu de la présentation clinique des amyloïdoses et du rôle des spécialistes dans la réalisation d'un bilan diagnostic précis et en temps opportun (2) Examen des meilleures pratiques de gestion multidisciplinaire de l'amyloïdose, y compris des variables pronostiques et des déterminants de la réponse au traitement (3) Mise à jour sur les traitements nouveaux et émergents dans la prise en charge des amyloïdoses à chaîne légère (AL) et à transthyrétine (ATTR). Limites: Ce symposium a donné lieu à une discussion multidisciplinaire de cas; les points d'apprentissage reflètent les évaluations des experts/auteurs concernés. Conclusion: L'identification et la prise en charge des amyloïdoses peuvent être facilitées par une approche multidisciplinaire et un indice de suspicion plus élevé de la part des cardiologues, des néphrologues et des hémato-oncologues. Une meilleure connaissance des présentations cliniques et des algorithmes de diagnostic pour le sous-typage de l'amyloïdose permettra d'intervenir plus rapidement et d'améliorer les résultats cliniques.

Transcriptomics of Hirschsprung disease patient-derived enteric neural crest cells reveals a role for oxidative phosphorylation.

Hirschsprung disease is characterized by the absence of enteric neurons caused by the defects of enteric neural crest cells, leading to intestinal obstruction. Here, using induced pluripotent stem cell-based models of Hirschsprung and single-cell transcriptomic analysis, we identify a gene set of 118 genes commonly dysregulated in all patient enteric neural crest cells, and suggest HDAC1 may be a key regulator of these genes. Furthermore, upregulation of RNA splicing mediators and enhanced alternative splicing events are associated with severe form of Hirschsprung. In particular, the higher inclusion rate of exon 9 in PTBP1 and the perturbed expression of a PTBP1-target, PKM, are significantly enriched in these patient cells, and associated with the defective oxidative phosphorylation and impaired neurogenesis. Hedgehog-induced oxidative phosphorylation significantly enhances the survival and differentiation capacity of patient cells. In sum, we define various factors associated with Hirschsprung pathogenesis and demonstrate the implications of oxidative phosphorylation in enteric neural crest development and HSCR pathogenesis.

Determining the Longitudinal Serologic Response to COVID-19 Vaccination in the Chronic Kidney Disease Population: A Clinical Research Protocol.

Background: People living with chronic kidney disease (CKD) have been disproportionately affected by the coronavirus disease 2019 (COVID-19) pandemic, including higher rates of infection, hospitalization, and death. Data on responsiveness to COVID-19 vaccination strategies and immunogenicity are limited, yet required to inform vaccination strategies in this at-risk population. Objective: The objective of this study is to characterize the longitudinal serologic response to COVID-19 vaccination. Design: This is a prospective observational cohort study. Setting: Participating outpatient kidney programs within Ontario and British Columbia. Patients: Up to 2500 participants with CKD G3b-5D receiving COVID-19 vaccination, including participants receiving dialysis and kidney transplant recipients (CKD G1T-5T). Measurements: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG antibodies (anti-spike, anti-receptor binding domain, anti-nucleocapsid) will be detected by ELISA (enzyme-linked immunosorbent assay) from serum or dried blood spot testing. In a subset of participants, neutralizing antibodies against novel variants of concern will be evaluated. Peripheral blood mononuclear cells will be collected for exploratory immune profiling of SARS-CoV-2 specific cellular immunity. Methods: Participants will be recruited prior to or following any COVID-19 vaccine dose and have blood sampled for serological testing at multiple timepoints: 1, 3, 6, 9, and 12 months post vaccination. When possible, samples will be collected prior to a dose or booster. Participants will remain in the study for at least 1 year following their last COVID-19 vaccine dose. Strengths and limitations: The adaptive design of this study allows for planned modification based on emerging evidence or rapid changes in public health policy surrounding vaccination. Limitations include incomplete earlier timepoints for blood collection due to rapid vaccination of the population. Conclusions: This large multicenter serologic study of participants living with kidney disease will generate data on the kinetics of SARS-CoV-2 immune response to vaccination across the spectrum of CKD, providing insights into the amplitude and duration of immunity conferred by COVID-19 vaccination and allowing for characterization of factors associated with immune response. The results of this study may be used to inform immunization guidelines and public health recommendations for the 4 million Canadians living with CKD.

Contexte: Les personnes atteintes d'insuffisance rénale chronique (IRC) ont été touchées de façon disproportionnée par la pandémie de COVID-19 ayant notamment présenté des taux plus élevés d'infection, d'hospitalisation et de décès. Les données sur la réactivité aux stratégies de vaccination de la COVID-19 et à l'immunogénicité sont limitées, mais elles sont nécessaires pour développer des stratégies de vaccination dans cette population à risque. Objectif: Caractériser la réponse sérologique longitudinale à la vaccination contre la COVID-19. Conception: Étude de cohorte observationnelle prospective. Cadre: Les programmes ambulatoires de santé rénale participants en Ontario et en Colombie-Britannique. Sujets: Jusqu'à 2 500 personnes atteintes d'IRC G3B-5D recevant un vaccin contre la COVID-19, y compris des patients suivant des traitements de dialyse et des receveurs d'une greffe rénale (IRC G1T-5T). Mesures: Les anticorps IgG anti-SARS-CoV-2 (anti-spike, anti-domaine de liaison au récepteur, anti-nucléocapside) seront détectés par ELISA à partir du sérum ou de taches de sang séché. Un sous-groupe de sujets participera également à l'évaluation d'anticorps neutralisants dirigés contre les nouveaux variants préoccupants. Des cellules mononuclées de sang périphérique seront prélevées pour établir un profil immunitaire exploratoire de l'immunité cellulaire spécifique au SARS-CoV-2. Méthodologie: Les sujets seront recrutés avant ou après toute dose du vaccin contre la COVID-19 et se soumettront à des prélèvements sanguins pour les tests sérologiques à 1, 3, 6, 9 et 12 mois post-vaccination. Lorsque possible, des échantillons seront prélevés avant l'administration d'une dose ou d'un rappel. Les sujets demeureront dans l'étude pendant au moins un an après leur dernière dose de vaccin contre la COVID-19. Points forts et limites: La conception adaptative de l'étude permet d'apporter des modifications planifiées fondées sur de nouvelles données ou des changements rapides dans les politiques de santé publique entourant la vaccination. Les résultats sont limités par l'absence de certains prélèvements sanguins antérieurs (point temporels) en raison de la vaccination rapide de la population. Conclusion: Cette vaste étude sérologique multicentrique menée auprès de personnes atteintes de néphropathie fournira des données sur la cinétique de la réponse immunitaire à la vaccination contre le SARS-CoV-2 dans l'ensemble du spectre de l'IRC. Elle fournira des informations sur l'amplitude et la durée de l'immunité conférée par la vaccination contre la COVID-19 et permettra de caractériser les facteurs associés à la réponse immunitaire. Ces résultats serviront à orienter les recommandations de santé publique et les lignes directrices en matière d'immunisation pour les quatre millions de Canadiens et Canadiennes qui vivent avec l'IRC.

Identification of cancer-related genes FGFR2 and CEBPB in choledochal cyst via RNA sequencing of patient-derived liver organoids.

BACKGROUND: Choledochal cysts (CC) are congenital bile duct anomalies with 6-30% risk for developing bile duct cancer. However, the molecular mechanisms underlying cancer risk of CC are unknown. We sought to identify the gene expression changes underlying the cancer risk of CC patients. METHODS: Liver organoids (n = 51) were generated from liver/bile duct biopsies of CC (n = 7; type I) and hepatoblastoma (n = 5; HB: non-tumor & tumor) for RNA sequencing. Bioinformatics analysis was conducted to identify differentially expressed cancer-related genes in CC and controls. We compared CC with non-cancerous and cancerous controls, normal adjacent non-tumor region of hepatoblastoma (HB) liver as non-cancerous control and tumor region as non-CC cancer control (HB-tumor). Reverse transcription real-time quantitative PCR (RT-qPCR) verification and immunohistochemistry of selected genes was conducted in additional CC and HB liver biopsies. FINDINGS: HB non-tumor and HB tumor organoids displayed distinct gene expression profiles. Expression profiling separated CC organoids into two clusters, one overlapping with HB non-tumor and the other one with HB tumor organoids. Genes selected based on their log2FoldChange values for RT-qPCR verification in 31 CC and 11 HB non-tumor liver tissues revealed significantly elevated expression of FGFR2 in 7 and CEBPB in 2 CC liver tissues (CC vs HB: 4.082 vs. 0.7671, p<0.01; 2.506 vs. 1.210, p<0.01). Distinctive positive staining in bile ducts were seen in CC, HB tumor and non-tumor liver tissues for FGFR2 and CEBPB. Percentages of CEBPB-immuno-positive or FGFR2-immuno-positive bile duct cells in CC and HB-tumor liver were higher than that in HB non-tumor liver. INTERPRETATION: The study identified dysregulated genes related to cancer pathways in CC patients suggesting cancer risk. The findings suggest that the elevated expression of FGFR2 and CEBPB in liver may contribute to cancer development in CC patients.

Functional patency rates of arteriovenous fistula of a retrospective cohort study from one of the biggest centers in Canada.

BACKGROUND: The main barriers to arterio-venous fistula (AVF) utilization are primary failure, long maturation duration, and low secondary patency rates. METHODS: In this retrospective cohort study, primary, secondary, functional primary, and functional secondary patency rates were calculated and compared between two age groups (< 75 years and > = 75 years) and between radiocephalic (RC-) and upper arm (UA-) AVFs, and factors determining the duration of functional secondary patency were evaluated. RESULTS: Between 2016 and 2020, 206 predialysis patients whose AVFs had been created previously initiated renal replacement treatment. RC-AVFs comprised 23.3% and were created after favorable analysis of the forearm vasculature. Overall, the primary failure rate was 8.3, and 84.7% started hemodialysis with a functioning AVF. Functional secondary patency rates of primary AVFs were better with RC-AVFs [1,3 and 5 year rates of 95.8, 81.9 and 81.9% versus 83.4, 71.8 and 59.2% for UA-AVFs (log rank p: 0.041)]. There was no difference between the two age groups for any of the AVF outcomes assessed. Among patients whose AVF was abandoned, 40.3% had gone on to have a second fistula created. This was significantly less likely in the older group (p < 0.01). IN CONCLUSION: (1) UA-AVFs were placed more commonly than RC-AVFs; (2) a selection bias existed whereby RC-AVFs were only created after favorable forearm vasculature was demonstrated or suspected; (3) superior functional secondary patency rates were observed with RC-AV's, perhaps stemming from this selection bias; (4) the elderly were more likely to have only one AVF creation attempt.

Genetics of Hirschsprung's disease.

Hirschsprung's disease (HSCR) is a classical model of enteric neuropathy, occurring in approximately 2-2.8 in 10,000 newborns. It is the commonest form of congenital bowel obstruction and is characterized by the absence of enteric ganglia in distal colon. Recent advances in genome-wide association analysis (GWAS) and next generation sequencing (NGS) studies have led to the discovery of a number of new HSCR candidate genes, thereby providing new insights into the genetic architecture and molecular mechanisms of the disease. Altogether, these findings indicated that genetic heterogeneity, variable penetrance and expressivity, and genetic interaction are the pervasive characteristics of HSCR genetics. In this review, we will provide an update on the genetic landscape of HSCR and discuss how the common and rare variants may act together to modulate the phenotypic manifestation. Translating the genetic findings to genetic risk prediction and to optimize clinical outcomes are undoubtedly the ultimate goals for genetic studies on HSCR. From this perspective, we will further discuss the major obstacles in the clinical translation of these latest genetic findings. Lastly, new measures to address these clinical challenges are suggested to advance precision medicine and to develop novel alternative therapies.

Bioengineering Liver Organoids for Diseases Modelling and Transplantation.

Organoids as three-dimension (3D) cellular organizations partially mimic the physiological functions and micro-architecture of native tissues and organs, holding great potential for clinical applications. Advances in the identification of essential factors including physical cues and biochemical signals for controlling organoid development have contributed to the success of growing liver organoids from liver tissue and stem/progenitor cells. However, to recapitulate the physiological properties and the architecture of a native liver, one has to generate liver organoids that contain all the major liver cell types in correct proportions and relative 3D locations as found in a native liver. Recent advances in stem-cell-, biomaterial- and engineering-based approaches have been incorporated into conventional organoid culture methods to facilitate the development of a more sophisticated liver organoid culture resembling a near to native mini-liver in a dish. However, a comprehensive review on the recent advancement in the bioengineering liver organoid is still lacking. Here, we review the current liver organoid systems, focusing on the construction of the liver organoid system with various cell sources, the roles of growth factors for engineering liver organoids, as well as the recent advances in the bioengineering liver organoid disease models and their biomedical applications.

Embryology and anatomy of Hirschsprung disease.

Bowel has its own elegant nervous system - the enteric nervous system (ENS) which is a complex network of neurons and glial clones. Derived from neural crest cells (NCCs), this little brain controls muscle contraction, motility, and bowel activities in response to stimuli. Failure of developing enteric ganglia at the distal bowel results in intestinal obstruction and Hirschsprung disease (HSCR). This Review summarises the important embryological development of the ENS including proliferation, migration, and differentiation of NCCs. We address the signalling pathways which determine NCC cell fate and discuss how they are altered in the context of HSCR. Finally, we outline the anatomical defects and the mechanisms underlying gut motility in HSCR.

Whole genome sequencing reveals epistasis effects within RET for Hirschsprung disease.

Common variants in RET and NRG1 have been associated with Hirschsprung disease (HSCR), a congenital disorder characterised by incomplete innervation of distal gut, in East Asian (EA) populations. However, the allelic effects so far identified do not fully explain its heritability, suggesting the presence of epistasis, where effect of one genetic variant differs depending on other (modifier) variants. Few instances of epistasis have been documented in complex diseases due to modelling complexity and data challenges. We proposed four epistasis models to comprehensively capture epistasis for HSCR between and within RET and NRG1 loci using whole genome sequencing (WGS) data in EA samples. 65 variants within the Topologically Associating Domain (TAD) of RET demonstrated significant epistasis with the lead enhancer variant (RET+3; rs2435357). These epistatic variants formed two linkage disequilibrium (LD) clusters represented by rs2506026 and rs2506028 that differed in minor allele frequency and the best-supported epistatic model. Intriguingly, rs2506028 is in high LD with one cis-regulatory variant (rs2506030) highlighted previously, suggesting that detected epistasis might be mediated through synergistic effects on transcription regulation of RET. Our findings demonstrated the advantages of WGS data for detecting epistasis, and support the presence of interactive effects of regulatory variants in RET for HSCR.

Immunomodulatory Mechanisms of Mesenchymal Stem Cells and Their Potential Clinical Applications.

Mesenchymal stem cells (MSCs) are multipotent stem cells with the capacity of self-renewal, homing, and low immunogenicity. These distinct biological characteristics have already shown immense potential in regenerative medicine. MSCs also possess immunomodulatory properties that can maintain immune homeostasis when the immune response is over-activated or under-activated. The secretome of MSCs consists of cytokines, chemokines, signaling molecules, and growth factors, which effectively contribute to the regulation of immune and inflammatory responses. The immunomodulatory effects of MSCs can also be achieved through direct cell contact with microenvironmental factors and immune cells. Furthermore, preconditioned and engineered MSCs can specifically improve the immunomodulation effects in diverse clinical applications. These multifunctional properties of MSCs enable them to be used as a prospective therapeutic strategy to treat immune disorders, including autoimmune diseases and incurable inflammatory diseases. Here we review the recent exploration of immunomodulatory mechanisms of MSCs and briefly discuss the promotion of the genetically engineered MSCs. Additionally, we review the potential clinical applications of MSC-mediated immunomodulation in four types of immune diseases, including systemic lupus erythematosus, Crohn's disease, graft-versus-host disease, and COVID-19.

Plasma amyloid-beta levels correlated with impaired hepatic functions: An adjuvant biomarker for the diagnosis of biliary atresia.

Background: Biliary atresia (BA) is an infantile fibro-obstructive cholestatic disease with poor prognosis. An early diagnosis and timely Kasai portoenterostomy (KPE) improve clinical outcomes. Aggregation of amyloid-beta (Aß) around hepatic bile ducts has been discovered as a factor for BA pathogenesis, yet whether plasma Aß levels correlate with hepatic dysfunctions and could be a biomarker for BA remains unknown. Method: Plasma samples of 11 BA and 24 controls were collected for liver function test, Aß40 and Aß42 measurement by enzyme-linked immunosorbent assay (ELISA). Pearson's chi-squared test or Mann-Whitney U test was performed to assess differences between groups. Correlation between Aß42/Aß40 and liver function parameters was performed using Pearson analysis. The area under the receiver-operative characteristic (ROC) curve (area under curve; AUC) was measured to evaluate the diagnostic power of Aß42/Aß40 for BA. Diagnostic enhancement was further evaluated by binary regression ROC analysis of Aß42/Aß40 combined with other hepatic function parameters. Results: Plasma Aß42/Aß40 was elevated in BA patients. Aß42 displayed a weak positive correlation with γ-glutamyl transpeptidase (GGT) (Pearson's correlation = 0.349), while there was no correlation for Aß40 with hepatic functions. Aß42/Aß40 was moderately correlated with GGT, total bile acid (TBA), direct bilirubin (DBIL) (Pearson's correlation = 0.533, 0.475, 0.480), and weakly correlated with total bilirubin (TBIL) (Pearson's correlation = 0.337). Aß42/Aß40 showed an acceptable predictive power for cholestasis [AUC = 0.746 (95% CI: 0.552-0.941), p < 0.05]. Diagnostic powers of Aß42/Aß40 together with hepatic function parameters for cholestasis were markedly improved compared to any indicator alone. Neither Aß42/Aß40 nor hepatic function parameters displayed sufficient power in discriminating BA from choledochal cysts (CC); however, combinations of Aß42/Aß40 + GGT along with any other hepatic function parameters could differentiate BA from CC-cholestasis (AUC = 1.000, p < 0.05) with a cut-off value as 0.02371, -0.28387, -0.34583, 0.06224, 0.01040, 0.06808, and 0.05898, respectively. Conclusion: Aß42/Aß40 is a good indicator for cholestasis, but alone is insufficient for a distinction of BA from non-BA. However, Aß42/Aß40 combined with GGT and one other hepatic function parameter displayed a high predictive power as a screening test for jaundiced neonates who are more likely to be BA, enabling them to early intraoperative cholangiography for BA confirmation and KPE to improve surgical outcomes. However, a multi-centers validation is needed before introduction into daily clinical practice.

Regenerative medicine: postnatal approaches.

Paper 2 of the paediatric regenerative medicine Series focuses on recent advances in postnatal approaches. New gene, cell, and niche-based technologies and their combinations allow structural and functional reconstitution and simulation of complex postnatal cell, tissue, and organ hierarchies. Organoid and tissue engineering advances provide human disease models and novel treatments for both rare paediatric diseases and common diseases affecting all ages, such as COVID-19. Preclinical studies for gastrointestinal disorders are directed towards oesophageal replacement, short bowel syndrome, enteric neuropathy, biliary atresia, and chronic end-stage liver failure. For respiratory diseases, beside the first human tracheal replacement, more complex tissue engineering represents a promising solution to generate transplantable lungs. Genitourinary tissue replacement and expansion usually involve application of biocompatible scaffolds seeded with patient-derived cells. Gene and cell therapy approaches seem appropriate for rare paediatric diseases of the musculoskeletal system such as spinal muscular dystrophy, whereas congenital diseases of complex organs, such as the heart, continue to challenge new frontiers of regenerative medicine.