The developmental etiology and pathogenesis of Hirschsprung disease

Intestinal Neuronal Dysplasia Type B: An Updated Review of a Problematic Diagnosis

Context.—

Intestinal neuronal dysplasia type B (IND B) is a controversial histopathologic phenotype that has been associated with intestinal dysmotility, either as an isolated condition or in conjunction with established pathologic disorders (eg, Hirschsprung disease). Many factors contribute to the debate over the existence and/or clinical significance of IND B, including a large body of published data based on inconsistent diagnostic criteria and methods, which have fostered many unwarranted conclusions that lack sufficient scientific basis.

Objective.—

To critically analyze existing published data regarding IND B to provide supporting evidence-based diagnostic practice and to stimulate necessary and scientifically sound research.

Data Sources.—

This update focuses on published literature related to the pathology of IND B because without a reliable pathologic diagnosis, studies of epidemiology, pathogenesis, natural history, management, and outcome are all suspect. Problems with existing data are identified explicitly with suggestions as to how future investigations should be designed and evaluated to better understand this entity.

Conclusions.—

Inconsistencies in diagnostic criteria and methods used to define IND B justifiably encumber the universal acceptance of IND B as a neuropathologic etiology for intestinal dysmotility. IND B will remain a controversial diagnosis until rigorous, well-controlled scientific studies are conducted to establish reproducible and reliable diagnostic criteria that reliably translate from one laboratory to another.

IGF2-derived miR-483-3p associated with Hirschsprung's disease by targeting FHL1

HSCR (Hirschsprung's disease) is a serious congenital defect, and the aetiology of it remains unclear. Many studies have highlighted the significant roles of intronic miRNAs and their host genes in various disease, few was mentioned in HSCR although. In this study, miR-483-3p along with its host gene IGF2 (Insulin-like growth factor 2) was found down-regulated in 60 HSCR aganglionic colon tissues compared with 60 normal controls. FHL1 (Four and a half LIM domains 1) was determined as a target gene of miR-483-3p via dual-luciferase reporter assay, and its expression was at a higher level in HSCR tissues. Here, we study cell migration and proliferation in human 293T and SH-SY5Y cell lines by performing Transwell and CCK8 assays. In conclusion, the knockdown of miR-483-3p and IGF2 both suppressed cell migration and proliferation, while the loss of FHL1 leads to opposite outcome. Furthermore, miR-483-3p mimics could rescue the negative effects on cell proliferation and migration caused by silencing IGF2, while the FHL1 siRNA may inverse the function of miR-483-3p inhibitor. This study revealed that miR-483-3p derived from IGF2 was associated with Hirschsprung's disease by targeting FHL1 and may provide a new pathway to understand the aetiology of HSCR.

Mutations in Smad-interacting protein 1 gene are responsible for absence of its expression in Hirschsprung's disease

Hirschsprung's disease (HSCR) is a common congenital malformation of the enteric nervous system. The pathophysiological basis remains unclear. Recently, the SIP1 gene has been recognized as being involved in the pathogenesis of symptomatic HSCR patients with 2q22 chromosomal rearrangement. In this study, mutations in SIP1 were analyzed to explore the relationship between SIP1 and HSCR. All exons of SIP1 were amplified and then analyzed by PCR-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing. SIP1 expression was determined by immunohistochemistry, Western blot and real-time quantitative PCR. By PCR-RFLP, three different electrophoretic bands of 536, 428 and 257 bp representing different genotypes were demonstrated accordingly. DNA sequencing revealed a heterozygous absence of codon 157 GTG → GTA exchange at exon 7. Simultaneously, exchanges of GCC → ACC at codon 351 and ACC → GCC at codon 395 were also observed in exon 8. All the exchanges caused a missense mutation. By immunohistochemistry, SIP1 was ectopically expressed in the aganglionic segment of HSCR without mutation. For comparison, in HSCR with mutation either in exon 7 or exon 8, SIP1 immunoreactivity disappeared in all structures. The protein and mRNA levels determined by Western blot and real-time quantitative PCR were consistent with that of immunohistochemistry. In summary, mutations of the SIP1 gene were detected in HSCR. These mutations in SIP1 were responsible for the absence of its expression in HSCR and contributed to the pathogenesis of this disease.

Association between DSCAM polymorphisms and non-syndromic Hirschsprung disease in Chinese population

Background

Hirschsprung disease (HSCR, aganglionic megacolon) is the most frequent genetic cause of congenital intestinal obstruction. DSCAM was identified as associated to HSCR with Down Syndrome (DS-HSCR) in European population,but failed to replicate in the non-syndromic HSCR patients. We aim to further investigate the relationship of DSCAM with non-sydromic HSCR in a South Chinese cohort, the largest case-control study so far.

Method

We analyzed 1394 HSCR patients and 973 healthy controls. Two polymorphisms (rs2837770 A > G, rs8134673 A > G) on DSCAM were genotyped using Sequenom Massarray platform.

Results

Both SNPs were confirmed as associated with non-syndromic HSCR in the South Chinese population (P = 1.69E-03, OR = 1.29 for SNP rs2837770 and P = 3.00E-03, OR = 1.27 for SNP rs8134637). Of note, we demonstrated the associated SNPs were more likely to affect a subgroup of patients with short-segment aganglionosis (S-HSCR) (P = 3.06E-03,OR = 1.21 for SNP rs2837770 and P = 3.33E-03,OR = 1.21 for SNP rs8134637).

Conclusion

There is an association between DSCAM polymorphisms and non-syndromic HSCR in South Chinese population.

Electronic supplementary material

The online version of this article (10.1186/s12881-018-0637-2) contains supplementary material, which is available to authorized users.

Discovery of a First-in-Class Gut-Restricted RET Kinase Inhibitor as a Clinical Candidate for the Treatment of IBS

Abdominal pain and abnormal bowel habits represent major symptoms for irritable bowel syndrome (IBS) patients that are not adequately managed. Although the etiology of IBS is not completely understood, many of the functions of the gastrointestinal (GI) tract are regulated by the enteric nervous system (ENS). Inflammation or stress-induced expression of growth factors or cytokines may lead to hyperinnervation of visceral afferent neurons in GI tract and contribute to the pathophysiology of IBS. Rearranged during transfection (RET) is a neuronal growth factor receptor tyrosine kinase critical for the development of the ENS as exemplified by Hirschsprung patients who carry RET loss-of-function mutations and lack normal colonic innervation leading to colonic obstruction. Similarly, RET signaling in the adult ENS maintains neuronal function by contributing to synaptic formation, signal transmission, and neuronal plasticity. Inhibition of RET in the ENS represents a novel therapeutic strategy for the normalization of neuronal function and the symptoms of IBS patients. Herein, we describe our screening effort and subsequent structure-activity relationships (SARs) in optimizing potency, selectivity, and mutagenicity of the series, which led to the discovery of a first-in-class, gut-restricted RET kinase inhibitor, 2-(4-(4-ethoxy-6-oxo-1,6-dihydropyridin-3-yl)-2-fluorophenyl)-N-(5-(1,1,1-trifluoro-2-methylpropan-2-yl)isoxazol-3-yl)acetamide (15, GSK3179106), as a clinical candidate for the treatment of IBS. GSK3179106 is a potent, selective, and gut-restricted pyridone hinge binder small molecule RET kinase inhibitor with a RET IC₅₀ of 0.3 nM and is efficacious in vivo.

Identification of two novel PCDHA9 mutations associated with Hirschsprung's disease

Hirschsprung's disease (HSCR) is a complex disorder with multiple pathogenic gene mutations. Protocadherin alpha 9 (PCDHA9) was identified as a potential candidate gene for HSCR by whole-exome sequencing in a Chinese family. Sanger sequencing in 298 HSCR cases revealed two sporadic Chinese patients with a novel missence PCDHΑ9 mutation (NM_031857; c.1280C > T[p.Ala427Val]) and one sporadic Chinese patient with another novel missence PCDHΑ9 mutation (c.1425C > G[p.Phe475Leu]).The silico predictions and 3D modeling suggest the deleterious effect of identified mutations on protein function. Immunohistochemistry analysis showed PCDHΑ9 was predominantly expressed in the myenteric plexus of human colon tissues. For mouse embryos, PCDHΑ9 was expressed in the stomach but rarely seen in the intestine during E10.5-12.5, then obviously expressed in the intestinal mucosa at E13.5 and extensively expressed in intestinal muscularis and mucosa at E14.5. Moreover, the down-regulation of PCDHΑ9 in the SH-SY5Y cell line promoted the proliferation and migration rate but inhibited the apoptotic rate. In summary, PCDHΑ9 is potentially related to HSCR and the clustered protocadherins (Pcdhs) may involve in the enteric nervous system (ENS) ontogeny.

Large-scale replication study identified multiple independent SNPs in RET synergistically associated with Hirschsprung disease in Southern Chinese population

Hischsprung disease (HSCR) is an intestinal disorder with strong genetic components. RET was considered as the strongest contributor. Multiple single nucleotide polymorphisms (SNP) were demonstrated as associated with HSCR in different populations. However, whether the associations of reported SNPs derived from one causal variants or congregations of multiple variants were still not clear. In this study, we successfully genotyped 16 SNPs in RET with a largest case-control study to date, totaling 1470 HSCR and 1473 control subjects in South Chinese population. Multiple independent contributors were identified through pairwise and stepwise logistic regression. The intragenic synergistic effect among these SNPs were further explored and cross validated by logistic regression and multifactor dimensionality reduction (MDR). Noteworthy, in further subclinical manifestation analysis, the six potential independent contributors in RET were more essential for the patients with short-segment aganglionosis (S-HSCR). Although functional evaluations are required, our comprehensive analysis for RET gene integrating detailed disease subphenotypes might facilitate improved understanding for the genetic understanding of HSCR etiology.

Association of VAMP5 and MCC genetic polymorphisms with increased risk of Hirschsprung disease susceptibility in Southern Chinese children

Hirschsprung disease (HSCR) is a genetic disorder characterized by the absence of neural crest cells in parts of the intestine. This study aims to investigate the association of vesicle-associated membrane protein 5 (VAMP5) and mutated in colorectal cancer (MCC) genetic polymorphisms and their correlated risks with HSCR. We examined the association in four polymorphisms (rs10206961, rs1254900 and rs14242 in VAMP5, rs11241200 in MCC) and HSCR susceptibility in a Southern Chinese population composed of 1473 cases and 1469 controls. Two variants in VAMP5 were replicated as associated with HSCR. Interestingly, we clarified SNPs rs10206961 and rs1254900 in VAMP5 are more essential for patients with long-segment aganglionosis (LHSCR). Relatively high expression correlation was observed between VAMP5 and MCC using data from public database showing there may exist potential genetic interactions. SNP interaction was cross-examined by logistic regression and multifactor dimensionality reduction analysis revealing that VAMP5 rs1254900 and MCC rs11241200 were interacting significantly, thereby contributing to the risk of HSCR. The results suggest that significant associations of the rs10206961 and rs14242 in VAMP5 with an increased risk of HSCR in Southern Chinese, especially in LHSCR patients. This study provided new evidence of epistatic association of VAMP5 and MCC with increased risk of HSCR.

Association of NRG1 and AUTS2 genetic polymorphisms with Hirschsprung disease in a South Chinese population

Hirschsprung disease (HSCR) is a genetic disorder characterized by the absence of enteric ganglia. There are more than 15 genes identified as contributed to HSCR by family-based or population-based approaches. However, these findings were not fulfilled to explain the heritability of most sporadic cases. In this study, using 1470 HSCR and 1473 control subjects in South Chinese population, we replicated two variants in NRG1 (rs16879552, P = 1.05E-04 and rs7835688, P = 1.19E-07), and further clarified the two replicated SNPs were more essential for patients with short-segment aganglionosis (SHSCR) (P = 2.37E-05). We also tried to replicate the most prominent signal (rs7785360) in AUTS2, which was a potential susceptibility gene with HSCR. In our results, in terms of individual association, marginal effect was observed to affect the HSCR patients following recessive model (P = 0.089). Noteworthy, significant intergenic synergistic effect between rs16879552 (NRG1) and rs7785360 (AUTS2) was identified through cross-validation by logistic regression (P = 2.45E-03, OR = 1.53) and multifactor dimensionality reduction (MDR, P < 0.0001, OR = 1.77). Significant correlation was observed between expression of these two genes in the normal segments of the colons (P = 0.018), together with differential expression of these genes between aganglionic colonic segments and normal colonic segments of the HSCR patients (P value for AUTS2 <0.0001, P value for NRG1 = 0.0243). Although functional evaluation is required, we supply new evidence for the NRG1 to HSCR and raised up a new susceptibility gene AUTS2 to a specific symptom for the disease.

A 6-year retrospective review of histopathological pattern of surgical biopsies in children with refractory constipation in a Tertiary Hospital in Ghana

BACKGROUND

Children with chronic constipation dating to infancy frequently undergo rectal biopsy in order to rule out Hirschsprung's disease (HD) which is a common cause of this sort of presentation. Few publications have however focused on the documentation of the proportion of such patients who truly had histopathological findings confirming the disease. In this preliminary work, we aim to present the histopathological findings of children who had rectal biopsies in our centre from 2009 to 2014.

PATIENTS AND METHODS

A retrospective study was undertaken to review the histopathology reports of all rectal biopsies submitted to the Department of Pathology of the Komfo Anokye Teaching Hospital, Kumasi, from 2009 to 2014 on account of refractory constipation and suspected HD. Patient's biodata, clinical signs and symptoms were extracted from the request form.

RESULTS

Eighty-eight cases were seen during the study period with male to female ratio 2.8:1 and age range 6 months to 10 years. The modal age range is 24-36 months. Seventy-six of the specimens were adequate for histopathological assessment with 64 cases confirmed as HD while 12 cases were normal. Out of the confirmed cases, 3 cases showed absence of ganglion cells but no hypertrophy of nerve fibres.

CONCLUSION

This preliminary work reveals that HD is rarely confirmed by biopsy in early infancy in our setting due to late presentation although the epidemiology of the disease is similar to that reported elsewhere.

Gli family zinc finger 1 is associated with endothelin receptor type B in Hirschsprung disease

Hirschsprung disease (HSCR) is a newborn colorectal disease characterized by an absence of ganglia in the distal gut. Hedgehog (Hh) and endothelin signaling serve important roles in gastrointestinal tract formation. Alterations in the signaling pathways disrupt the development of enteric neural crest cells (ENCCs). It is not known whether there is any coordination between these pathways in the pathogenesis of HSCR. In the present study, tissue samples from 35 patients with HSCR, including stenotic aganglionosis gut and normal ganglionic gut, were obtained. The expression of Gli family zinc finger 1 (Gli1) and endothelin receptor type B (EDNRB) was determined using reverse transcription-quantitative polymerase chain reaction, immunohistochemistry and western blotting. In addition, the SK-N-SH cell line was used to investigate the association between Hh signaling and the expression of EDNRB. The results revealed aberrant expression of Gli1 in the aganglionic segments, as well as decreased expression of Gli1 in tissues from 7 patients with HSCR exhibited, whereas tissues from 9 patients with HSCR exhibited increased Gli1 expression compared with the expression in the normal tissues. There was a negative association between EDNRB expression and Gli1 expression in the same sample. Knockdown of Gli1 by small interfering RNA and inhibition of Hh signaling by Vismodegib in SK-N-SH cells increased EDNRB expression. By contrast, upregulation of Gli1 expression by plasmids and activation of Hh signaling by Purmorphamine decreased EDNRB expression. Furthermore, premature enteric ganglia were observed in 4 patients with HSCR with decreased Gli1 expression. Thus, the results of the present study suggest that altered Gli1 expression negatively regulates EDNRB expression in patients with HSCR. The increased expression of EDNRB induced by decreased Gli1 expression may represent a novel mechanism in HSCR.

Altered expression of laminin alpha1 in aganglionic colon of endothelin receptor-B null mouse model of Hirschsprung's disease

PURPOSE

Laminin, an extracellular matrix molecule, is essential for normal development of the nervous system. The alpha1 subunit of laminin-1 (LAMA1) has been reported to promote neurites and outgrowth and is expressed only during embryogenesis. Previously, we developed a Sox10 transgenic version of the Endothelin receptor-B (Ednrb) mouse to visualize Enteric neural crest-derived cell (ENCC)s with a green fluorescent protein, Venus. We designed this study to investigate the expression of LAMA1 using Sox10-VENUS mice gut.

METHODS

We harvested the gut on days 13.5 (E13.5) and 15.5 (E15.5) of gestation. Sox10-VENUS⁺/Ednrb ^-/- mice (n = 8) were compared with Sox10-VENUS⁺/Ednrb ^+/+ mice (n = 8) as controls. Gene expression of LAMA1 was analysed by real-time RT-PCR. Fluorescent immunohistochemistry was performed to assess protein distribution.

RESULTS

The relative mRNA expression levels of LAMA1 were significantly increased in HD in the proximal and distal colon on E15.5 compared to controls (p < 0.05), whereas there were no significant differences on E13.5. LAMA1 was expressed in the serosa, submucosa and basal lamina in the gut, and was markedly increased in the proximal and distal colon of HD on E15.5.

CONCLUSIONS

Altered LAMA1 expression in the aganglionic region may contribute to impaired ENCC migration, resulting in HD. These data could help in understanding the pathophysiologic interactions between LAMA1 and ENCC migration.

The challenges of closing an ileostomy in patients with total intestinal aganglionosis after small bowel transplant

We present the case of a 14-year-old male with a history of small bowel transplantation for long segment Hirschsprung's disease who underwent Duhamel ileorectal pull-through procedure. In post-transplant, the patient had no restrictions and was not TPN-dependent. To improve his quality of life, he and his family were interested in closing the ileostomy and undergoing pull-through surgery. The complexity of the case includes the presence of an aganglionic rectal segment-a short root of the mesentery due to the small bowel transplant-and significant immunosuppression. At the moment, he is continent, doing well, and has not had any remarkable complications.

Alteration of the Retinoid Acid-CBP Signaling Pathway in Neural Crest Induction Contributes to Enteric Nervous System Disorder

Hirschsprung Disease (HSCR) and/or hypoganglionosis are common pediatric disorders that arise from developmental deficiencies of enteric neural crest cells (ENCCs). Retinoid acid (RA) signaling has been shown to affect neural crest (NC) development. However, the mechanisms underlying RA deficiency-induced HSCR or hypoganglionosis are not well-defined. In this report, we found that in HSCR patient bowels, the RA nuclear receptor RARα and its interacting coregulator CREB-binding protein (CBP) were expressed in enteric neural plexuses in the normal ganglionic segment. However, the expression of these two genes was significantly inhibited in the pathological aganglionic segment. In a Xenopus laevis animal model, endogenous RARα interacted with CBP and was expressed in NC territory. Morpholino-mediated knockdown of RARα blocked expression of the NC marker genes Sox10 and FoxD3 and inhibited NC induction. The morphant embryos exhibited reduced nervous cells in the gastrointestinal anlage, a typical enteric nervous deficiency-associated phenotype. Injection of CBP mRNA rescued NC induction and reduced enteric nervous deficiency-associated phenotypes. Our work demonstrates that RARα regulates Sox10 expression via CBP during NC induction, and alteration of the RA-CBP signaling pathway may contribute to the development of enteric nervous system disorders.

Downregulation of lncRNA MEG3 and miR-770-5p inhibit cell migration and proliferation in Hirschsprung's disease

The long noncoding RNA (lncRNA) MEG3 is involved in various biological processes including cell migration and cell proliferation. In present study, it was found that MEG3 and the intronic miR-770-5p were decreased in samples from HSCR patients. Besides, knockdown of MEG3 and miR-770-5p suppressed cell migration and proliferation, while cell cycle and apoptosis were not affected in human 293T and SH-SY5Y cells. SRGAP1 mRNA and protein upregulation was inversely correlated with miR-770-5p expression in tissue samples and cell lines, which was confirmed to be a target gene of miR-770-5p by dual-luciferase reporter assay. Moreover, silencing of SRGAP1 rescued the inhibition of cell migration and proliferation induced by MEG3 siRNA and miR-770-5p inhibition. The present study elucidates a novel mechanism of the development of HSCR and shows that the MEG3/miR-770-5p/SRGAP1 pathway plays a vital role in the pathogenesis of HSCR.

LncRNA AFAP1-AS Functions as a Competing Endogenous RNA to Regulate RAP1B Expression by sponging miR-181a in the HSCR

Background: Long noncoding RNAs (lncRNAs) have recently emerged as important regulators in a broad spectrum of cellular processes including development and disease. Despite the known engagement of the AFAP1-AS in several human diseases, its biological function in Hirschsprung disease (HSCR) remains elusive. Methods: We used qRT-PCR to detect the relative expression of AFAP1-AS in 64 HSCR bowel tissues and matched normal intestinal tissues. The effects of AFAP1-AS on cell proliferation, migration, cell cycle, apoptosis and cytoskeletal organization were evaluated using CCK-8, transwell assay, flow cytometer analysis and immunofluorescence, in 293T and SH-SY5Y cell lines, respectively. Moreover, the competing endogenous RNA (ceRNA) activity of AFAP1-AS on miR-181a was investigated via luciferase reporter assay and immunoblot analysis. Results: Aberrant inhibition of AFAP1-AS was observed in HSCR tissues. Knockdown of AFAP1-AS in 293T and SH-SY5Y cells suppressed cell proliferation, migration, and induced the loss of cell stress filament integrity, possibly due to AFAP1-AS sequestering miR-181a in HSCR cells. Furthermore, AFAP1-AS could down-regulate RAP1B via its competing endogenous RNA (ceRNA) activity on miR-181a. Conclusions: These findings suggest that aberrant expression of lncRNA AFAP1-AS, a ceRNA of miR-181a, may involve in the onset and progression of HSCR by augmenting the miR-181a target gene, RAP1B.

Upregulation of MiR-369-3p suppresses cell migration and proliferation by targeting SOX4 in Hirschsprung's disease

BACKGROUND

Hirschsprung disease (HSCR) is a congenital digestive disease in the new born. miR-369-3p has been reported to be involved in many human diseases. However, the relationship between miR-369-3p and HSCR remains largely unknown.

METHODS

In this study, qRT-PCR was used to detect the relative expression of miR-369-3p in 60 HSCR bowel tissue samples and 47 matched controls. Bioinformatic analysis and dual-luciferase reporter assay were performed to evaluate the target for miR-369-3p. Cell Counting Kit-8 (CCK-8) assay, Transwell assay, wound healing assay and flow cytometry were employed to investigate the biological function of miR-369-3p in human SH-SY5Y and 293T cell lines.

RESULTS

We found that ganglion cell numbers were remarkably reduced while miR-369-3p was significantly upregulated in HSCR tissues compared to that in adjacent normal tissues (P<0.01). Dual-luciferase reporter assay showed that the 3'-UTR of SOX4 was a direct target to miR-369-3p. Moreover, an increased level of miR-369-3p was inversely correlated with decreased levels of SOX4 mRNA and protein (P<0.05, respectively). Dysregulation of miR-369-3p and SOX4 significantly suppressed cell proliferation and migration in SH-SY5Y and 293T cell lines in vitro (P<0.05, respectively).

CONCLUSION

Our study demonstrates that aberrant expression of miR-369-3p might play a crucial role in the development HSCR by regulating SOX4 expression, which may infer that it is an effective diagnostic target in the pathogenesis of HSCR, but investigation is still needed to explore the underlying mechanism.

Maternal use of selective serotonin reuptake inhibitors during pregnancy is associated with Hirschsprung's disease in newborns - a nationwide cohort study

BACKGROUND

Hirschsprung's disease is a rare condition caused by congenital malformation of the gastrointestinal tract affecting 1:5000 children. Not much is known about risk factors for development of Hirschsprung's disease. Two clinical cases of hirschsprung's disease led to an investigation of the association between maternal use of selective serotonin reuptake inhibitors (SSRIs) during pregnancy and development of Hirschsprung's Disease in the newborn child. The study examined a nationwide, unselected cohort of children born in Denmark from 1 January 1996 until 12 March 2016 (n = 1,256,317). We applied multivariate models to register-based data to estimate the odds ratio of Hirschsprung's disease, adjusting for possible confounders. The studied exposure period for SSRIs were 30 days prior to conception to the end of the first trimester.

RESULTS

In the main exposed cohort the prevalence of Hirschsprung's disease was 16/19.807 (0.08%) compared to 584/1.236.510 (0.05%) in the unexposed cohort. In women who redeemed a minimum of one prescription of selective serotonin reuptake inhibitors, the adjusted odds ratio for development of Hirschsprung's disease was 1.76 (95%CI: 1.07-2.92). In women who redeemed a minimum of two prescriptions, the adjusted odds ratio for Hirschsprung's disease was 2.34 (95% CI: 1.21-4.55).

CONCLUSIONS

Our data suggest that early maternal use of selective serotonin reuptake inhibitors is significantly associated with the development of Hirschsprung's disease in the newborn child. Treatment of depression during pregnancy always has to be weighed against the risks posed by untreated maternal depression. Our results have to be confirmed in other studies.

Defining the transcriptomic landscape of the developing enteric nervous system and its cellular environment

BACKGROUND

Motility and the coordination of moving food through the gastrointestinal tract rely on a complex network of neurons known as the enteric nervous system (ENS). Despite its critical function, many of the molecular mechanisms that direct the development of the ENS and the elaboration of neural network connections remain unknown. The goal of this study was to transcriptionally identify molecular pathways and candidate genes that drive specification, differentiation and the neural circuitry of specific neural progenitors, the phox2b expressing ENS cell lineage, during normal enteric nervous system development. Because ENS development is tightly linked to its environment, the transcriptional landscape of the cellular environment of the intestine was also analyzed.

RESULTS

Thousands of zebrafish intestines were manually dissected from a transgenic line expressing green fluorescent protein under the phox2b regulatory elements [Tg(phox2b:EGFP) ^w37 ]. Fluorescence-activated cell sorting was used to separate GFP-positive phox2b expressing ENS progenitor and derivatives from GFP-negative intestinal cells. RNA-seq was performed to obtain accurate, reproducible transcriptional profiles and the unbiased detection of low level transcripts. Analysis revealed genes and pathways that may function in ENS cell determination, genes that may be identifiers of different ENS subtypes, and genes that define the non-neural cellular microenvironment of the ENS. Differential expression analysis between the two cell populations revealed the expected neuronal nature of the phox2b expressing lineage including the enrichment for genes required for neurogenesis and synaptogenesis, and identified many novel genes not previously associated with ENS development. Pathway analysis pointed to a high level of G-protein coupled pathway activation, and identified novel roles for candidate pathways such as the Nogo/Reticulon axon guidance pathway in ENS development.

CONCLUSION

We report the comprehensive gene expression profiles of a lineage-specific population of enteric progenitors, their derivatives, and their microenvironment during normal enteric nervous system development. Our results confirm previously implicated genes and pathways required for ENS development, and also identify scores of novel candidate genes and pathways. Thus, our dataset suggests various potential mechanisms that drive ENS development facilitating characterization and discovery of novel therapeutic strategies to improve gastrointestinal disorders.

Cell therapy for GI motility disorders: comparison of cell sources and proposed steps for treating Hirschsprung disease

Cell therapeutic approaches to treat a range of congenital and degenerative neuropathies are under intense investigation. There have been recent significant advancements in the development of cell therapy to treat disorders of the enteric nervous system (ENS), enteric neuropathies. These advances include the efficient generation of enteric neural progenitors from pluripotent stem cells and the rescue of a Hirschsprung disease model mouse following their transplantation into the bowel. Furthermore, a recent study provides evidence of functional innervation of the bowel muscle by neurons derived from transplanted ENS-derived neural progenitors. This mini-review discusses these recent findings, compares endogenous ENS-derived progenitors and pluripotent stem cell-derived progenitors as a cell source for therapy, and proposes the key steps for cell therapy to treat Hirschsprung disease.

Radiologist performance in the interpretation of contrast enemas performed for Hirschsprung's disease in children >1 year of age

AIM

To evaluate the diagnostic performance of contrast enemas (CEs) for the diagnosis of Hirschsprung's disease (HD).

METHODS AND MATERIALS

CE studies performed as part of an HD workup in patients 1-18 years of age over a 10-year period were identified. All abnormal CE studies and an equal number of age-matched controls were included in the final study group. Two radiologists independently and blindly reviewed all CE studies for quality (scale of 0-3) and the presence of large colon calibre, colon redundancy, transition zone, rectosigmoid ratio, and abnormal contractions. Readers also determined whether a rectal biopsy would be recommended to confirm an HD diagnosis. Discrepancies were resolved in consensus. Findings were correlated with surgery and biopsy data.

RESULTS

Out of 834 CE studies, 38 abnormal CE studies were identified (mean age 5.9 years) and included 38 matched controls. Seventeen of 76 patients were recommended for rectal biopsy, of which five were confirmed to have HD. Twelve of 70 (17.1%) were false positives, and were clinically confirmed not to have HD. The proportion of HD in the present population was 6/834 (0.72%). Of the 17 recommended for biopsy, CE studies showed 17/17 (100%) with an abnormal rectosigmoid ratio, 16/17 (94.1%) with redundant colon, and 15/17 (88%) with large colon. Of patients not recommended for biopsy, one was diagnosed with HD, (false negative, 16.7%). The diagnostic performance of CE was 83.3% sensitivity and 82.9% specificity.

CONCLUSION

Few children >1 year of age were found to have HD and the diagnostic performance of the CE is moderately high. The CE examination is a valuable non-invasive imaging study to help exclude older children who may not have HD, thereby obviating the need for invasive rectal biopsy and surgery.

Reprogramming Postnatal Human Epidermal Keratinocytes Toward Functional Neural Crest Fates

During development, neural crest (NC) cells are induced by signaling events at the neural plate border of all vertebrate embryos. Initially arising within the central nervous system, NC cells subsequently undergo an epithelial to mesenchymal transition to migrate into the periphery, where they differentiate into diverse cell types. Here we provide evidence that postnatal human epidermal keratinocytes (KC), in response to fibroblast growth factor 2 and insulin like growth factor 1 signals, can be reprogrammed toward a NC fate. Genome-wide transcriptome analyses show that keratinocyte-derived NC cells are similar to those derived from human embryonic stem cells. Moreover, they give rise in vitro and in vivo to NC derivatives such as peripheral neurons, melanocytes, Schwann cells and mesenchymal cells (osteocytes, chondrocytes, adipocytes, and smooth muscle cells). By demonstrating that human keratin-14+ KC can form NC cells, even from clones of single cells, our results have important implications in stem cell biology and regenerative medicine. Stem Cells 2017;35:1402-1415.

Abundance and Significance of Neuroligin-1 and Neurexin II in the Enteric Nervous System of Embryonic Rats

Aim. To investigate the abundance of neuroligin-1 and neurexin II in the enteric nervous system (ENS) of rats on different embryonic days and to explore their potential significance. Methods. The full-thickness colon specimens proximal to the ileocecal junction of rats on embryonic days 16, 18, and 20 and of newborns within 24 hours (E16, E18, E20, and Ep0) were studied, respectively. qRT-PCR was applied for detecting the expressions of neuroligin-1 and neurexin II on mRNA, and western blotting was employed for detecting their further expressions on the whole tissue. Finally, the histological appearance of neuroligin-1 and neurexin IIα was elucidated using immunohistochemical staining. Results. qRT-PCR showed that the neuroligin-1 and neurexin II mRNA expressions of groups E16, E18, E20, and Ep0 increased gradually with the growth of embryonic rats (P < 0.05). Western blotting confirmed the increasing tendency. In immunohistochemical staining, proteins neuroligin-1 and neurexin IIα positive cells concentrated mostly in the myenteric nerve plexus of the colon and their expressions depend on the embryonic time. Conclusion. Neuroligin-1 and neurexin II were both expressed in the ENS and have temporal correlation with the development of ENS, during which neuronal intestinal malformations (NIM) may occur due to their disruptions and consequent abnormal ENS development.

Hirschsprung's disease: clinical dysmorphology, genes, micro-RNAs, and future perspectives

On the occasion of the 100th anniversary of Dr. Harald Hirschsprung's death, there is a worldwide significant research effort toward identifying and understanding the role of genes and biochemical pathways involved in the pathogenesis as well as the use of new therapies for the disease harboring his name (Hirschsprung disease, HSCR). HSCR (aganglionic megacolon) is a frequent diagnostic and clinical challenge in perinatology and pediatric surgery, and a major cause of neonatal intestinal obstruction. HSCR is characterized by the absence of ganglia of the enteric nervous system, mostly in the distal gastrointestinal tract. This review focuses on current understanding of genes and pathways associated with HSCR and summarizes recent knowledge related to micro RNAs (miRNAs) and HSCR pathogenesis. While commonly sporadic, Mendelian patterns of inheritance have been described in syndromic cases with HSCR. Although only half of the patients with HSCR have mutations in specific genes related to early embryonic development, recent pathway-based analysis suggests that gene modules with common functions may be associated with HSCR in different populations. This comprehensive profile of functional gene modules may serve as a useful resource for future developmental, biochemical, and genetic studies providing insights into the complex nature of HSCR.

Recent advances in regenerative medicine to treat enteric neuropathies: use of human cells

As current options for treating most enteric neuropathies are either non-effective or associated with significant ongoing problems, cell therapy is a potential attractive possibility to treat congenital and acquired neuropathies. Studies using animal models have shown that following transplantation of enteric neural progenitors into the bowel of recipients, the transplanted cells migrate, proliferate, and generate neurons that are electrically active and receive synaptic inputs. Recent studies have transplanted human enteric neural progenitors into the mouse colon and shown engraftment. In this article, we summarize the significance of these recent advances and discuss priorities for future research that might lead to the use of regenerative medicine to treat enteric neuropathies in the clinic.

Identifying key genes associated with Hirschsprung's disease based on bioinformatics analysis of RNA-sequencing data

BACKGROUND

Hirschsprung's disease (HSCR) is a type of megacolon induced by deficiency or dysfunction of ganglion cells in the distal intestine and is associated with developmental disorders of the enteric nervous system. To explore the mechanisms of HSCR, we analyzed the RNA-sequencing data of the expansion and the narrow segments of colon tissues separated from children with HSCR.

METHODS

RNA-sequencing of the expansion segments and the narrow segments of colon tissues isolated from children with HSCR was performed. After differentially expressed genes (DEGs) were identified using the edgeR package in R, functional and pathway enrichment analyses of DEGs were carried out using DAVID software. To further screen the key genes, protein-protein interaction (PPI) network and module analyses were conducted separately using Cytoscape software.

RESULTS

A total of 117 DEGs were identified in the expansion segment samples, including 47 up-regulated and 70 down-regulated genes. Functional enrichment analysis suggested that FOS and DUSP1 were implicated in response to endogenous stimulus. In the PPI network analysis, FOS (degree=20), EGR1 (degree=16), ATF3 (degree=9), NOS1 (degree=8), CCL5 (degree=8), DUSP1 (degree=7), CXCL3 (degree=6), VIP (degree=6), FOSB (degree=5), and NOS2 (degree=4) had higher degrees, which could interact with other genes. In addition, two significant modules (module 1 and module 2) were identified from the PPI network.

CONCLUSIONS

Several genes (including FOS, EGR1, ATF3, NOS1, CCL5, DUSP1, CXCL3, VIP, FOSB, and NOS2) might be involved in the development of HSCR through their effect on the nervous system.

PRDM1/BLIMP1 is widely distributed to the nascent fetal-placental interface in the mouse gastrula

BACKGROUND

PRDM1 is a transcriptional repressor that contributes to primordial germ cell (PGC) development. During early gastrulation, epiblast-derived PRDM1 is thought to be restricted to a lineage-segregated germ line in the allantois. However, given recent findings that PGCs overlap an allantoic progenitor pool that contributes widely to the fetal-umbilical interface, posterior PRDM1 may also contribute to soma.

RESULTS

Within the posterior mouse gastrula (early streak, 12-s stages, embryonic days ∼6.75-9.0), PRDM1 localized to all tissues containing putative PGCs; however, PRDM1 was also found in all three primary germ layers, their derivatives, and two presumptive growth centers, the allantoic core domain and ventral ectodermal ridge. While PRDM1 and STELLA colocalized predominantly within the hindgut, where putative PGCs reside, other colocalizing cells were found in non-PGC sites. Additional PRDM1 and STELLA cells were found independent of each other throughout the posterior region, including the hindgut. The Prdm1-Cre-driven reporter supported PRDM1 localization in the majority of sites; however, some Prdm1 descendants were found in sites independent of PRDM1 protein, including allantoic mesothelium and hindgut endoderm.

CONCLUSIONS

Posterior PRDM1 contributes more broadly to the developing fetal-maternal connection than previously recognized, and PRDM1 and STELLA, while overlapping in putative PGCs, also co-localize in several other tissues. Developmental Dynamics 246:50-71, 2017. © 2016 Wiley Periodicals, Inc.

Apoptotic neuron-secreted HN12 inhibits cell apoptosis in Hirschsprung's disease

Perturbation in apoptosis can lead to Hirschsprung's disease (HSCR), which is a genetic disorder of neural crest development. It is believed that long noncoding RNAs (lncRNAs) play a role in the progression of HSCR. This study shows that apoptotic neurons can suppress apoptosis of nonapoptotic cells by secreting exosomes that contain high levels of HN12 lncRNA. Elevated exogenous HN12 in nonapoptotic cells effectively inhibited cell apoptosis by maintaining the function of mitochondria, including the production of ATP and the release of cytochrome C. These results demonstrate that secreted lncRNAs may serve as signaling molecules mediating intercellular communication in HSCR. In addition, high HN12 levels in the circulation worked as a biomarker for predicting HSCR, providing a potential, novel, noninvasive diagnostic approach for early screening of HSCR.

Phenotype and distribution pattern of nestin-GFP-expressing cells in murine myenteric plexus

The enteric nervous system has to adapt to altering dietary or environmental conditions and presents an enormous plasticity that is conserved over the whole lifespan. It harbours neural-crest-derived neurons, glial cells and their precursors. Based on a nestin-green fluorescent protein (NGFP) transgenic model, a histological inventory has been performed to deliver an overview of neuronal and glial markers for the various parts of the gastrointestinal tract in newborn (postnatal day 7) and adult mice under homeostatic conditions. Whereas NGFP-positive glial cells can be found in all parts of the gut at any individual age, a specific NGFP population is present with both neuronal morphology and marker expression in the myenteric plexus (nNGFP). These cells appear in variable quantities, depending on age and location. Their overall abundance decreases from newborn to adults and their spatial distribution is also age-dependent. In newborn gut, nNGFP cells are found in similar quantities throughout the gut, with a significantly lower presence in the duodenum. Their expression increases in the adult mouse from the stomach to the colon. All of these nNGFP cells expressed either (but not both) of the glia markers S100 or glial fibrillary acidic protein (GFAP). In the S100-positive glia population, a subset of cells also shows a neuronal morphology (nS100), without expressing nestin. Thus, the presence of premature neurons that express NGFP demonstrates that neurogenesis takes place far beyond birth. In enteric neurons, NGFP acts as a marker for neuronal plasticity showing the differentiation and change in the phenotype of neuronal precursor cells.

Detection of autophagy in Hirschsprung's disease: implication for its role in aganglionosis

Hirschsprung's disease (HD) is a common congenital gastrointestinal malformation, characterized by the lack of ganglion cells from the distal rectum to the proximal bowel, but the pathogenesis is not well understood. This paper evaluates the effects of autophagy in HD. Using electron microscopy, the autophagosomes were detected in three segments: narrow segment (NS), transitional segment (TS), and dilated segment (DS). Typical autophagosome structures are found in the Auerbach plexus of both NS and TS. Real-time PCR results showed that Beclin1 (NS vs. TS, P<0.01) and LC3 (NS vs. TS, P<0.05) mRNA were the highest in the NS, but p75 (NS vs. TS, P<0.01) was the highest in the DS. Correlation analysis results showed a positive correlation between Beclin1 and LC3 mRNA levels (R=0.736, P=0.000), whereas inverse correlations were found between p75 and Beclin1/LC3 mRNA levels (p75 vs. Beclin1: R=-0.714, P=0.000; p75 vs. LC3: R=-0.619, P=0.000). Immunohistochemistry analyses indicated a consistent result with mRNA levels, by increased Beclin1-positive and LC3-positive neurons, but reduced p75-positive neurons in the Auerbach plexus of TS compared with DS. These findings indicated that autophagy exists in the bowel of patients with HD. On the basis of the detection of the highest expression of the autophagy genes in NS, autophagy may additionally cause the lack of neurons.

Mouse models of Hirschsprung disease and other developmental disorders of the enteric nervous system: Old and new players

Hirschsprung disease (HSCR, intestinal aganglionosis) is a multigenic disorder with variable penetrance and severity that has a general population incidence of 1/5000 live births. Studies using animal models have contributed to our understanding of the developmental origins of HSCR and the genetic complexity of this disease. This review summarizes recent progress in understanding control of enteric nervous system (ENS) development through analyses in mouse models. An overview of signaling pathways that have long been known to control the migration, proliferation and differentiation of enteric neural progenitors into and along the developing gut is provided as a framework for the latest information on factors that influence enteric ganglia formation and maintenance. Newly identified genes and additional factors beyond discrete genes that contribute to ENS pathology including regulatory sequences, miRNAs and environmental factors are also introduced. Finally, because HSCR has become a paradigm for complex oligogenic diseases with non-Mendelian inheritance, the importance of gene interactions, modifier genes, and initial studies on genetic background effects are outlined.

Anti-Glypican 3, a Novel Ancillary Maker in the Histological Assessment of Hirschsprung's Disease

OBJECTIVES

Hirschsprung's disease (HSCR) results from a malformation of the enteric nervous system. A congenital absence of intrinsic ganglion cells from the distal rectum and a variable length of the contiguous bowel is the required diagnostic feature of Hirschsprung's disease and total colonic aganglionosis (TCA). We evaluated the utility of a monoclonal antibody directed against glypican 3 (GPC-3), a membrane bound protein involved in regulation of the signaling of Wingless-types (WNTs), Hedgehogs (Hh), Fibroblast Growth Factors (FGFs), and Bone Morphogenetic Proteins (BMPs), in the detection of ganglion cells in formalin-fixed, paraffin-embedded tissue sections.

METHODS

The presence/absence of ganglion cells was evaluated retrospectively by immunohistochemical staining for calretinin and GPC-3 in tissue specimens; a total of 15 patients who underwent colectomy (total or sub-total) for histologically proven aganglionosis (14 HSCR, 1 TCA) and 5 rectal suction biopsies (4HSCR-B, 1 TCA-B) were considered. Of the 20 considered cases, a total of 60 tissue specimens (3 for each patient) were selected. A total of 30 additional normal (N) colonic mucosa biopsy samples were also included.

RESULTS

GPC-3 constantly identified ganglion cell bodies in all but 2 normal biopsies (with normal presentation of ganglion cells on hematoxylin and eosin (H&E) stain), and was negative in all 60 aganglionotic biopsies; these results were reflective of calretinin staining pattern.

CONCLUSIONS

The present study indicates that monoclonal anti-GPC-3 might prove to be useful immunohistochemical marker in the identification of ganglion cells in paraffin-embedded rectal tissue specimens and suction biopsies. Further studies in larger series will contribute to demonstrate its utility as an ancillary marker in the histological assessment of HSCR aganglionosis.

Hirschsprung disease and hepatoblastoma: case report of a rare association

CONTEXT

Hirschsprung disease is a developmental disorder of the enteric nervous system that is characterized by absence of ganglion cells in the distal intestine, and it occurs in approximately 1 in every 500,000 live births. Hepatoblastoma is a malignant liver neoplasm that usually occurs in children aged 6 months to 3 years, with a prevalence of 0.54 cases per 100,000.

CASE REPORT

A boy diagnosed with intestinal atresia in the first week of life progressed to a diagnosis of comorbid Hirschsprung disease. Congenital cataracts and sensorineural deafness were diagnosed. A liver mass developed and was subsequently confirmed to be a hepatoblastoma, which was treated by means of surgical resection of 70% of the liver volume and neoadjuvant chemotherapy (ifosfamide, cisplatin and doxorubicin).

CONCLUSION

It is known that Hirschsprung disease may be associated with syndromes predisposing towards cancer, and that hepatoblastoma may also be associated with certain congenital syndromes. However, co-occurrence of hepatoblastoma and Hirschsprung disease has not been previously described. We have reported a case of a male patient born with ileal atresia, Hirschsprung disease and bilateral congenital cataract who was later diagnosed with hepatoblastoma.

Deficiency of platelet-derived growth factor receptor-α-positive cells in Hirschsprung's disease colon

AIM: To investigate whether the expression of platelet-derived growth factor receptor-α-positive (PDGFRα⁺)-cells is altered in Hirschsprung’s disease (HD).

METHODS: HD tissue specimens (n = 10) were collected at the time of pull-through surgery, while colonic control samples were obtained at the time of colostomy closure in patients with imperforate anus (n = 10). Immunolabelling of PDGFRα⁺-cells was visualized using confocal microscopy to assess the distribution of these cells, while Western blot analysis was undertaken to quantify PDGFRα protein expression.

RESULTS: Confocal microscopy revealed PDGFRα⁺-cells within the mucosa, myenteric plexus and smooth muscle in normal controls, with a marked reduction in PDGFRα⁺-cells in the HD specimens. Western blotting revealed high levels of PDGFRα protein expression in normal controls, while there was a striking decrease in PDGFRα protein expression in the HD colon.

CONCLUSION: These findings suggest that the altered distribution of PDGFRα⁺-cells in both the aganglionic and ganglionic HD bowel may contribute to the motility dysfunction in HD.

Reduced cell proliferation and increased apoptosis in the hippocampal formation in a rat model of Hirschsprung's disease

Hirschsprung's disease (HSCR) is a congenital malformation characterized by the absence of enteric ganglia in the distal intestine and gut obstruction. Some HSCR patients also have associated neurological symptoms. We studied a rat model of HSCR, also known as spotting lethal (sl/sl) rat, which carries a spontaneous deletion in the gene of endothelin receptor B (EDNRB) and a similar phenotype as humans with HSCR. We focused on the changes in cell proliferation and apoptosis in the hippocampal formation of the sl/sl rat. Proliferating cells in wildtype (+/+), heterozygous (+/sl) and homozygous (sl/sl) rats were labelled by intraperitoneal injection of 5-bromo-2'-deoxyuridine (BrdU) at postnatal day 2. The density of proliferating cells in the CA1 and CA3 regions of the hippocampus and dentate gyrus of sl/sl rats was significantly reduced compared to +/+ rats. The effect of EDNRB mutation on cell apoptosis was examined by using terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling assay. This showed that the density of apoptotic cells in the hippocampal formation, particularly in the CA1 region of sl/sl rats, was significantly increased compared to +/+ rats. The expression of brain derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) was measured with ELISA in the hippocampal formation, but no difference was revealed between genotypes. These results suggest that EDNRB mutation reduces cell proliferation and increases apoptosis in the hippocampal formation of the sl/sl rat, but does not alter the levels of BDNF and GDNF. Our findings provide an insight into the cellular changes in the brains of HSCR patients caused by EDNRB mutation.

How Tissue Mechanical Properties Affect Enteric Neural Crest Cell Migration

Neural crest cells (NCCs) are a population of multipotent cells that migrate extensively during vertebrate development. Alterations to neural crest ontogenesis cause several diseases, including cancers and congenital defects, such as Hirschprung disease, which results from incomplete colonization of the colon by enteric NCCs (ENCCs). We investigated the influence of the stiffness and structure of the environment on ENCC migration in vitro and during colonization of the gastrointestinal tract in chicken and mouse embryos. We showed using tensile stretching and atomic force microscopy (AFM) that the mesenchyme of the gut was initially soft but gradually stiffened during the period of ENCC colonization. Second-harmonic generation (SHG) microscopy revealed that this stiffening was associated with a gradual organization and enrichment of collagen fibers in the developing gut. Ex-vivo 2D cell migration assays showed that ENCCs migrated on substrates with very low levels of stiffness. In 3D collagen gels, the speed of the ENCC migratory front decreased with increasing gel stiffness, whereas no correlation was found between porosity and ENCC migration behavior. Metalloprotease inhibition experiments showed that ENCCs actively degraded collagen in order to progress. These results shed light on the role of the mechanical properties of tissues in ENCC migration during development.

Search for the missing lncs: gene regulatory networks in neural crest development and long non-coding RNA biomarkers of Hirschsprung's disease

Hirschsprung's disease (HSCR), a birth defect characterized by variable aganglionosis of the gut, affects about 1 in 5000 births and is a consequence of abnormal development of neural crest cells, from which enteric ganglia derive. In the companion article in this issue (Shen et al., Neurogasterenterol Motil 28: 266-73), the authors search for long non-coding RNAs (lncRNAs) differentially expressed in bowel tissues of infants with HSCR. Microarray analysis of over 37 000 lncRNAs and 34 000 mRNAs was done. The key result was identification of a set of 5 lncRNAs that is a potential diagnostic biomarker of HSCR. In this minireview, I provide an overview of neural crest development and the gene regulatory networks involved in specification, epithelial-mesenchymal transition, and migration of neural crest cells. Genes involved in later development, proliferation, and differentiation of neural crest cells as they migrate into the gut are also reviewed. Many of these genes are associated with HSCR, including RET, GDNF, GFRα, EDN3, and EDNRB. LncRNAs and their roles in development and disease and their use as biomarkers are discussed. The authors of the companion article previously used a multipronged approach to elucidate the etiology of HSCR by examining the effects of specific miRNAs or lncRNAs and target genes on cell migration, proliferation, cell cycle, and apoptosis in vitro. These studies are discussed in terms of their elegance and limitations. The companion article identifies many new lncRNAs that, in addition to providing potential biomarkers of HSCR, may be a treasure trove for future investigations.

Developmental Biology: We Are All Walking Mutants

What is Developmental Biology? Developmental Biology is a discipline that evolved from the collective fields of embryology, morphology, and anatomy, which firmly established that structure underpins function. In its simplest terms, Developmental Biology has come to describe how a single cell becomes a completely formed organism. However, this definition of Developmental Biology is too narrow. Developmental Biology describes the properties of individual cells; their organization into tissues, organs, and organisms; their homeostasis, regeneration, aging, and ultimately death. Developmental Biology provides a context for cellular reprogramming, stem cell biology, regeneration, tissue engineering, evolutionary development and ecology, and involves the reiterated use of the same cellular mechanisms and signaling pathways throughout the lifespan of an organism. Using neural crest cells as an example, this review explores the contribution of Developmental Biology to our understanding of development, evolution, and disease.

Neuroblastoma and Its Zebrafish Model

Neuroblastoma, an important developmental tumor arising in the peripheral sympathetic nervous system (PSNS), accounts for approximately 10 % of all cancer-related deaths in children. Recent genomic analyses have identified a spectrum of genetic alterations in this tumor. Amplification of the MYCN oncogene is found in 20 % of cases and is often accompanied by mutational activation of the ALK (anaplastic lymphoma kinase) gene, suggesting their cooperation in tumor initiation and spread. Understanding how complex genetic changes function together in oncogenesis has been a continuing and daunting task in cancer research. This challenge was addressed in neuroblastoma by generating a transgenic zebrafish model that overexpresses human MYCN and activated ALK in the PSNS, leading to tumors that closely resemble human neuroblastoma and new opportunities to probe the mechanisms that underlie the pathogenesis of this tumor. For example, coexpression of activated ALK with MYCN in this model triples the penetrance of neuroblastoma and markedly accelerates tumor onset, demonstrating the interaction of these modified genes in tumor development. Further, MYCN overexpression induces adrenal sympathetic neuroblast hyperplasia, blocks chromaffin cell differentiation, and ultimately triggers a developmentally-timed apoptotic response in the hyperplastic sympathoadrenal cells. In the context of MYCN overexpression, activated ALK provides prosurvival signals that block this apoptotic response, allowing continued expansion and oncogenic transformation of hyperplastic neuroblasts, thus promoting progression to neuroblastoma. This application of the zebrafish model illustrates its value in rational assessment of the multigenic changes that define neuroblastoma pathogenesis and points the way to future studies to identify novel targets for therapeutic intervention.

Surgical Intervention to Rescue Hirschsprung Disease in a Rat Model

Background/Aims

Rats with a spontaneous null mutation in endothelin receptor type B or Ednrb (sl/sl; spotting lethal) lack enteric neurons in the distal bowel and usually die within the first week after birth. This early postnatal lethality limits their use for examining the potential of cell therapy to treat Hirschsprung disease, and for studies of the influence of EDNRB on the mature CNS and vascular systems.

Methods

We have developed a surgical intervention to prolong the life of the spotting lethal sl/sl rat, in which we perform a colostomy on postnatal (P) day 4–6 rats to avoid the fatal obstruction caused by the lack of colonic enteric neurons.

Results

The stomas remained patent and functional and the rats matured normally following surgery. Weight gains were comparable between control and Hirschsprung phenotype (sl/sl) rats, which were followed until 4 weeks after surgery (5 weeks old). We confirmed the absence of enteric neurons in the distal colon of rats whose lives were saved by the surgical intervention.

Conclusions

This study provides a novel approach for studying EDNRB signalling in multiple organ systems in mature rats, including an animal model to study the efficacy of cell therapy to treat Hirschsprung disease.

Expression and function of Neuregulin 1 and its signaling system ERBB2/3 in the enteric nervous system

Neuregulin 1 (NRG1) is suggested to promote the survival and maintenance of the enteric nervous system (ENS). As deficiency in its corresponding receptor signaling complex ERBB2/ERBB3 leads to postnatal colonic hypo/aganglionosis we assessed the distributional and expressional pattern of the NRG1-ERBB2/ERBB3 system in the human colon and explored the neurotrophic capacity of NRG1 on cultured enteric neurons. Site-specific mRNA expression of the NRG1-ERBB2/3 system was determined in microdissected samples harvested from enteric musculature and ganglia. Localization of NRG1, ERBB2 and ERBB3 was determined by dual-label-immunohistochemistry using pan-neuronal and pan-glial markers. Morphometric analysis was performed on NRG1-stimulated rat enteric nerve cultures to evaluate neurotrophic effects. mRNA expression of the NRG1-ERBB2/3 system was determined by qPCR. Co-localization of NRG1 with neuronal or synaptic markers was analyzed in enteric nerve cultures stimulated with glial cell line-derived neurotrophic factor (GDNF). The NRG1 system was expressed in both neurons and glial cells of enteric ganglia and in nerve fibers. NRG1 significantly enhanced growth parameters in enteric nerve cell cultures and ErB3 mRNA expression was down-regulated upon NRG1 stimulation. GDNF negatively regulates ErbB2 and ErbB3 mRNA expression. The NRG1-ERBB2/3 system is physiologically present in the human ENS and NRG1 acts as a neurotrophic factor for the ENS. The down-regulation of ErbB3/ErbB2 in GDNF stimulated nerve cell cultures points to an interaction of both neurotrophic factors. Thus, the data may provide a basis to assess disturbed signaling components of the NRG1 system in enteric neuropathies.

Novel mutation-deletion in the PHOX2B gene of the patient diagnosed with Neuroblastoma, Hirschsprung's Disease, and Congenital Central Hypoventilation Syndrome (NB-HSCR-CCHS) Cluster

INTRODUCTION

Neuroblastoma (NB), Hirschsprung disease (HSCR), Congenital Central Hypoventilation Syndrome (CCHS), clinically referred as the NB-HSCR-CCHS cluster, are genetic disorders linked to mutations in the PHOX2B gene on chromosome 4p12.

SPECIFIC AIM

The specific aim of this project is to define the PHOX2B gene mutations as the genomic basis for the clinical manifestations of the NB-HSCR-CCHS cluster.

PATIENT

A one day old male patient presented to the Jagiellonian University Medical College (JUMC), American Children Hospital, neonatal Intensive Care Unit (ICU) due to abdominal distention, vomiting, and severe apneic episodes. With the preliminary diagnosis of the NB-HSCR-CCHS, the blood and tissue samples were acquired from the child, as well as from the child's parents. All procedures were pursued in accordance with the Declaration of Helsinki, with the patient's Guardian Informed Consent and the approval from the Institutional Review Board.

GENETIC/GENOMIC METHODS

Karyotyping was analyzed based upon Giemsa banding. The patient's genomic DNA was extracted from peripheral blood and amplified by polymerase chain reaction. Direct microfluidic Sanger sequencing was performed on the genomic DNA amplicons. These procedures were pursued in addition to the routine clinical examinations and tests.

RESULTS

G-banding showed the normal 46 XY karyotype. However, genomic sequencing revealed a novel, heterozygous deletion (8 nucleotides: c.699-706, del8) in exon 3 of the PHOX2B gene on chromosome 4. This led to the frame-shift mutation and malfunctioning gene expression product.

CONCLUSION

Herein, we report a novel PHOX2B gene mutation in the patient diagnosed with the NB-HSCR-CCHS cluster. The resulting gene expression product may be a contributor to the clinical manifestations of these genetic disorders. It adds to the library of the mutations linked to this syndrome. Consequently, we suggest that screening for the PHOX2B mutations becomes an integral part of genetic counseling, genomic sequencing of fetal circulating nucleic acids and / or genomes of circulating fetal cells prenatally, while preparing supportive therapy upon delivery, as well as on neonates' genomes of intubated infants, when breathing difficulties occur upon extubation. Further, we hypothesize that PHOX2B may be considered as a potential target for gene therapy.

VEGF signals induce trailblazer cell identity that drives neural crest migration

Embryonic neural crest cells travel in discrete streams to precise locations throughout the head and body. We previously showed that cranial neural crest cells respond chemotactically to vascular endothelial growth factor (VEGF) and that cells within the migratory front have distinct behaviors and gene expression. We proposed a cell-induced gradient model in which lead neural crest cells read out directional information from a chemoattractant profile and instruct trailers to follow. In this study, we show that migrating chick neural crest cells do not display distinct lead and trailer gene expression profiles in culture. However, exposure to VEGF in vitro results in the upregulation of a small subset of genes associated with an in vivo lead cell signature. Timed addition and removal of VEGF in culture reveals the changes in neural crest cell gene expression are rapid. A computational model incorporating an integrate-and-switch mechanism between cellular phenotypes predicts migration efficiency is influenced by the timescale of cell behavior switching. To test the model hypothesis that neural crest cellular phenotypes respond to changes in the VEGF chemoattractant profile, we presented ectopic sources of VEGF to the trailer neural crest cell subpopulation and show diverted cell trajectories and stream alterations consistent with model predictions. Gene profiling of trailer cells that diverted and encountered VEGF revealed upregulation of a subset of 'lead' genes. Injection of neuropilin1 (Np1)-Fc into the trailer subpopulation or electroporation of VEGF morpholino to reduce VEGF signaling failed to alter trailer neural crest cell trajectories, suggesting trailers do not require VEGF to maintain coordinated migration. These results indicate that VEGF is one of the signals that establishes lead cell identity and its chemoattractant profile is critical to neural crest cell migration.

Long none coding RNA HOTTIP/HOXA13 act as synergistic role by decreasing cell migration and proliferation in Hirschsprung disease

Long noncoding RNAs (lncRNAs) have been confirmed to be associated with various human diseases. However, whether they are associated with Hirschsprung disease (HSCR) progression remains unclear. In this study, we designed the experiment to explore the relationship between lncRNA HOTTIP and HOXA13, and their pathogenicity to HSCR. Quantitative real-time PCR and Western blot were performed to detect the levels of lncRNA, mRNAs, and proteins in colon tissues from 79 patients with HSCR and 79 controls. Small RNA interference transfection was used to study the function experiments in human 293T and SK-N-BE cell lines. The cell viability and activities were detected by the transwell assays, CCK8 assay, and flow cytometry, respectively. LncRNA HOTTIP and HOXA13 were significantly down-regulated in HSCR compared to the controls. Meanwhile, the declined extent of their expression levels makes sense between two main phenotype of HSCR. SiRNA-mediated knock-down of HOTTIP or HOXA13 correlated with decreased levels of each other and both reduced the cell migration and proliferation without affecting cell apoptosis or cell cycle. Our study demonstrates that aberrant reduction of HOTTIP and HOXA13, which have a bidirectional regulatory loop, may play an important role in the pathogenesis of HSCR.

Subnuclear re-localization of SOX10 and p54NRB correlates with a unique neurological phenotype associated with SOX10 missense mutations

SOX10 is a transcription factor with well-known functions in neural crest and oligodendrocyte development. Mutations in SOX10 were first associated with Waardenburg-Hirschsprung disease (WS4; deafness, pigmentation defects and intestinal aganglionosis). However, variable phenotypes that extend beyond the WS4 definition are now reported. The neurological phenotypes associated with some truncating mutations are suggested to be the result of escape from the nonsense-mediated mRNA decay pathway; but, to date, no mechanism has been suggested for missense mutations, of which approximately 20 have now been reported, with about half of the latter shown to be redistributed to nuclear bodies of undetermined nature and function in vitro. Here, we report that p54NRB, which plays a crucial role in the regulation of gene expression during many cellular processes including differentiation, interacts synergistically with SOX10 to regulate several target genes. Interestingly, this paraspeckle protein, as well as two other members of the Drosophila behavior human splicing (DBHS) protein family, co-localize with SOX10 mutants in nuclear bodies, suggesting the possible paraspeckle nature of these foci or re-localization of the DBHS members to other subnuclear compartments. Remarkably, the co-transfection of wild-type and mutant SOX10 constructs led to the sequestration of wild-type protein in mutant-induced foci. In contrast to mutants presenting with additional cytoplasmic re-localization, those exclusively found in the nucleus alter synergistic activity between SOX10 and p54NRB. We propose that such a dominant negative effect may contribute to or be at the origin of the unique progressive and severe neurological phenotype observed in affected patients.

Polymorphisms in endothelin system genes, arsenic levels and obesity risk

BACKGROUND/OBJECTIVES

Obesity has been linked to morbidity and mortality through increased risk for many chronic diseases. Endothelin (EDN) system has been related to endothelial function but it can be involved in lipid metabolism regulation: Receptor type A (EDNRA) activates lipolysis in adipocytes, the two endothelin receptors mediate arsenic-stimulated adipocyte dysfunction, and endothelin system can regulate adiposity by modulating adiponectin activity in different situations and, therefore, influence obesity development. The aim of the present study was to analyze if single nucleotide polymorphisms (SNPs) in the EDN system could be associated with human obesity.

SUBJECTS/METHODS

We analyzed two samples of general-population-based studies from two different regions of Spain: the VALCAR Study, 468 subjects from the area of Valencia, and the Hortega Study, 1502 subjects from the area of Valladolid. Eighteen SNPs throughout five genes were analyzed using SNPlex.

RESULTS

We found associations for two polymorphisms of the EDNRB gene which codifies for EDN receptor type B. Genotypes AG and AA of the rs5351 were associated with a lower risk for obesity in the VALCAR sample (p=0.048, OR=0.63) and in the Hortega sample (p=0.001, OR=0.62). Moreover, in the rs3759475 polymorphism, genotypes CT and TT were also associated with lower risk for obesity in the Hortega sample (p=0.0037, OR=0.66) and in the VALCAR sample we found the same tendency (p=0.12, OR=0.70). Furthermore, upon studying the pooled population, we found a stronger association with obesity (p=0.0001, OR=0.61 and p=0.0008, OR=0.66 for rs5351 and rs3759475, respectively). Regarding plasma arsenic levels, we have found a positive association for the two SNPs studied with obesity risk in individuals with higher arsenic levels in plasma: rs5351 (p=0.0054, OR=0.51) and rs3759475 (p=0.009, OR=0.53).

CONCLUSIONS

Our results support the hypothesis that polymorphisms of the EDNRB gene may influence the susceptibility to obesity and can interact with plasma arsenic levels.

SNAP-25 is abundantly expressed in enteric neuronal networks and upregulated by the neurotrophic factor GDNF

Control of intestinal motility requires an intact enteric neurotransmission. Synaptosomal-associated protein 25 (SNAP-25) is an essential component of the synaptic vesicle fusion machinery. The aim of the study was to investigate the localization and expression of SNAP-25 in the human intestine and cultured enteric neurons and to assess its regulation by the neurotrophic factor glial cell line-derived neurotrophic factor (GDNF). SNAP-25 expression and distribution were analyzed in GDNF-stimulated enteric nerve cell cultures, and synaptic vesicles were evaluated by scanning and transmission electron microscopy. Human colonic specimens were processed for site-specific SNAP-25 gene expression analysis and SNAP-25 immunohistochemistry including dual-labeling with the pan-neuronal marker PGP 9.5. Additionally, gene expression levels and distributional patterns of SNAP-25 were analyzed in colonic specimens of patients with diverticular disease (DD). GDNF-treated enteric nerve cell cultures showed abundant expression of SNAP-25 and exhibited granular staining corresponding to synaptic vesicles. SNAP-25 gene expression was detected in all colonic layers and isolated myenteric ganglia. SNAP-25 co-localized with PGP 9.5 in submucosal and myenteric ganglia and intramuscular nerve fibers. In patients with DD, both SNAP-25 mRNA expression and immunoreactive profiles were decreased compared to controls. GDNF-induced growth and differentiation of cultured enteric neurons is paralleled by increased expression of SNAP-25 and formation of synaptic vesicles reflecting enhanced synaptogenesis. The expression of SNAP-25 within the human enteric nervous system and its downregulation in DD suggest an essential role in enteric neurotransmission and render SNAP-25 as a marker for impaired synaptic plasticity in enteric neuropathies underlying intestinal motility disorders.

Immunohistochemical panel for the diagnosis of Hirschsprung's disease using antibodies to MAP2, calretinin, GLUT1 and S100

AIMS

The diagnosis of Hirschsprung's disease is currently based on the identification of aganglionosis and the presence of an increase in acetylcholinesterase-positive hypertrophic nerve fibres in the large bowel submucosa. However, acetylcholinesterase staining is laborious and requires a skilled technician. The aim of this study was to identify a method for diagnosing Hirschsprung's disease reliably using an immunohistochemical panel of recently proposed markers.

METHODS AND RESULTS

Sixty-nine specimens from 37 patients were evaluated. MAP2 and calretinin antibodies were shown to stain ganglia reliably in the submucosal and myenteric plexuses of normal tissue. By contrast, reduced staining of ganglia was observed in patients with Hirschsprung's disease. Staining for GLUT1 and S100 was used to evaluate the number and thickness of nerve fibres. Gain of GLUT1 and S100 expression was in contrast to the loss of calretinin and MAP2. Hypertrophic submucosal nerve fibres in Hirschsprung's disease develop a perineurium with a ring-like GLUT1 staining pattern similar in size and intensity to that observed in deeper subserosal tissue.

CONCLUSIONS

The diagnosis of Hirschsprung's disease using immunohistochemical panels could be as accurate as with conventional frozen section techniques. In particular, the use of a combination of markers for ganglia and hypertrophic nerve fibres highlighting a prominent perineurium in Hirschsprung's disease could be an alternative method.

Neural crest cell evolution: how and when did a neural crest cell become a neural crest cell

As vertebrates evolved from protochordates, they shifted to a more predatory lifestyle, and radiated and adapted to most niches of the planet. This process was largely facilitated by the generation of novel vertebrate head structures, which were derived from neural crest cells (NCC). The neural crest is a unique vertebrate cell population that is frequently termed the "fourth germ layer" because it forms in conjunction with the other germ layers and contributes to a diverse array of cell types and tissues including the craniofacial skeleton, the peripheral nervous system, and pigment cells among many other tissues and cell types. NCC are defined by their origin at the neural plate border, via an epithelial-to-mesenchymal transition (EMT), together with multipotency and polarized patterns of migration. These defining characteristics, which evolved independently in the germ layers of invertebrates, were subsequently co-opted through their gene regulatory networks to form NCC in vertebrates. Moreover, recent data suggest that the ability to undergo an EMT was one of the latter features co-opted by NCC. In this review, we discuss the potential origins of NCC and how they evolved to contribute to nearly all tissues and organs throughout the body, based on paleontological evidence together with an evaluation of the evolution of molecules involved in NCC development and their migratory cell paths.

Neuroblastoma: molecular pathogenesis and therapy

Neuroblastoma is a developmental tumor of young children arising from the embryonic sympathoadrenal lineage of the neural crest. Neuroblastoma is the primary cause of death from pediatric cancer for children between the ages of one and five years and accounts for ∼13% of all pediatric cancer mortality. Its clinical impact and unique biology have made this aggressive malignancy the focus of a large concerted translational research effort. New insights into tumor biology are driving the development of new classification schemas. Novel targeted therapeutic approaches include small-molecule inhibitors as well as epigenetic, noncoding-RNA, and cell-based immunologic therapies. In this review, recent insights regarding the pathogenesis and biology of neuroblastoma are placed in context with the current understanding of tumor biology and tumor/host interactions. Systematic classification of patients coupled with therapeutic advances point to a future of improved clinical outcomes for this biologically distinct and highly aggressive pediatric malignancy.