The ITGB2 immunomodulatory gene (CD18), enterocolitis, and Hirschsprung's disease

Exploring the common mechanism of vascular dementia and inflammatory bowel disease: a bioinformatics-based study

Objective

Emerging evidence has shown that gut diseases can regulate the development and function of the immune, metabolic, and nervous systems through dynamic bidirectional communication on the brain-gut axis. However, the specific mechanism of intestinal diseases and vascular dementia (VD) remains unclear. We designed this study especially, to further clarify the connection between VD and inflammatory bowel disease (IBD) from bioinformatics analyses.

Methods

We downloaded Gene expression profiles for VD (GSE122063) and IBD (GSE47908, GSE179285) from the Gene Expression Omnibus (GEO) database. Then individual Gene Set Enrichment Analysis (GSEA) was used to confirm the connection between the two diseases respectively. The common differentially expressed genes (coDEGs) were identified, and the STRING database together with Cytoscape software were used to construct protein-protein interaction (PPI) network and core functional modules. We identified the hub genes by using the Cytohubba plugin. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were applied to identify pathways of coDEGs and hub genes. Subsequently, receiver operating characteristic (ROC) analysis was used to identify the diagnostic ability of these hub genes, and a training dataset was used to verify the expression levels of the hub genes. An alternative single-sample gene set enrichment (ssGSEA) algorithm was used to analyze immune cell infiltration between coDEGs and immune cells. Finally, the correlation between hub genes and immune cells was analyzed.

Results

We screened 167 coDEGs. The main articles of coDEGs enrichment analysis focused on immune function. 8 shared hub genes were identified, including PTPRC, ITGB2, CYBB, IL1B, TLR2, CASP1, IL10RA, and BTK. The functional categories of hub genes enrichment analysis were mainly involved in the regulation of immune function and neuroinflammatory response. Compared to the healthy controls, abnormal infiltration of immune cells was found in VD and IBD. We also found the correlation between 8 shared hub genes and immune cells.

Conclusions

This study suggests that IBD may be a new risk factor for VD. The 8 hub genes may predict the IBD complicated with VD. Immune-related coDEGS may be related to their association, which requires further research to prove.

A pilot study characterizing longitudinal changes in fecal microbiota of patients with Hirschsprung-associated enterocolitis

PURPOSE

Hirschsprung disease is a neurointestinal disease that occurs due to failure of enteric neural crest-derived cells to complete their rostrocaudal migration along the gut mesenchyme, resulting in aganglionosis along variable lengths of the distal bowel. Despite the effective surgery that removes the aganglionic segment, children with Hirschsprung disease remain at high risk for developing a potentially life-threatening enterocolitis (Hirschsprung-associated enterocolitis). Although the etiology of this enterocolitis remains poorly understood, several recent studies in both mouse models and in human subjects suggest potential involvement of gastrointestinal microbiota in the underlying pathogenesis of Hirschsprung-associated enterocolitis.

METHODS

We present the first study to exploit the Illumina MiSeq next-generation sequencing platform within a longitudinal framework focused on microbiomes of Hirschsprung-associated enterocolitis in five patients. We analyzed bacterial communities from fecal samples collected at different timepoints starting from active enterocolitis and progressing into remission.

RESULTS

We observed compositional differences between patients largely attributable to variability in age at the time of sample collection. Remission samples across patients exhibited compositional similarity, including enrichment of Blautia, while active enterocolitis samples showed substantial variability in composition.

CONCLUSIONS

Overall, our findings provide continued support for the role of GI microbiota in the pathogenesis of Hirschsprung-associated enterocolitis.

Immunocastration with gene vaccine (KISS1) induces a cell-mediated immune response in ram testis: A transcriptome evaluation

Immunocastration vaccines achieve their effects through neutralization of the endogenous hormone by the humoral antibody produced against the immunized genes. But there is little information regarding cell-mediated immune response on the gonadal function of the immunized model is available. In this study, we used ram as a model animal to identify the cellular immune response in testicular tissues of rams immunized with intranasal KISS1 gene vaccine. The immune castration model was evaluated by sexual behaviors, spermatogenesis, and serum hormone profiles after the KISS1 gene immunization. Transcriptome analysis of testicular tissues was carried out to identify the expressions of protein-coding genes involved in cellular immunity. The results showed that we successfully constructed the KISS1 immune castration ram model, in which testicular growth and development, testosterone and kisspeptin-54 levels, and sexual function were suppressed in immunized rams (P <0.05). Using HiseqTM 2000 high sequencing for ram testicular, we identified 21 differentially expressed genes (DEGs) related to cellular immunity, of which, 14 genes were up-regulated and seven genes were down-regulated in the testis of the immunized group (P<0.05). The Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment showed that these differentially expressed genes were enriched in the antigen presentation process mediated by MHC class I and the cytotoxic pathway mediated by natural killer cells. It is concluded that KISS1 gene vaccine induced the cell-mediated immune response in testicular tissue to suppress reproductive activities in rams.

Integrating genetics, physiology and morphology to study desert adaptation in a lizard species

Integration of multiple approaches is key to understand the evolutionary processes of local adaptation and speciation. Reptiles have successfully colonized desert environments, that is, extreme and arid conditions that constitute a strong selective pressure on organisms. Here, we studied genomic, physiological and morphological variations of the lizard Liolaemus fuscus to detect adaptations to the Atacama Desert. By comparing populations of L. fuscus inhabiting the Atacama Desert with populations from the Mediterranean forests from central Chile, we aimed at characterizing features related to desert adaptation. We combined ddRAD sequencing with physiological (evaporative water loss, metabolic rate and selected temperature) and morphological (linear and geometric morphometrics) measurements. We integrated the genomic and phenotypic data using redundancy analyses. Results showed strong genetic divergence, along with a high number of fixed loci between desert and forest populations. Analyses detected 110 fixed and 30 outlier loci located within genes, from which 43 were in coding regions, and 12 presented non-synonymous mutations. The candidate genes were associated with cellular membrane and development. Desert lizards presented lower evaporative water loss than those from the forest. Morphological data showed that desert lizards had smaller body size, different allometry, larger eyeballs and more dorsoventrally compressed heads. Our results suggest incipient speciation between desert and forest populations. The adaptive signal must be cautiously interpreted since genetic drift could also contribute to the divergence pattern. Nonetheless, we propose water and resource availability, and changes in habitat structure, as the most relevant challenges for desert reptiles. This study provides insights of the mechanisms that allow speciation as well as desert adaptation in reptiles at multiple levels, and highlights the benefit of integrating independent evidence.

Single-Cell Transcriptome Analysis Identifies Ligand-Receptor Pairs Associated With BCP-ALL Prognosis

B cell precursor acute lymphoblastic leukemia (BCP-ALL) is a blood cancer that originates from the abnormal proliferation of B-lymphoid progenitors. Cell population components and cell–cell interaction in the bone marrow microenvironment are significant factors for progression, relapse, and therapy resistance of BCP-ALL. In this study, we identified specifically expressed genes in B cells and myeloid cells by analyzing single-cell RNA sequencing data for seven BCP-ALL samples and four healthy samples obtained from a public database. Integrating 1356 bulk RNA sequencing samples from a public database and our previous study, we found a total of 57 significant ligand–receptor pairs (24 upregulated and 33 downregulated) in the autocrine crosstalk network of B cells. Via assessment of the communication between B cells and myeloid cells, another 29 ligand–receptor pairs were discovered, some of which notably affected survival outcomes. A score-based model was constructed with least absolute shrinkage and selection operator (LASSO) using these ligand–receptor pairs. Patients with higher scores had poorer prognoses. This model can be applied to create predictions for both pediatric and adult BCP-ALL patients.

ITGB2 (Integrin β2) Immunomodulatory Gene Variants in Premature Infants With Necrotizing Enterocolitis

Aberrant toll-like receptor (TLR) activation is central to necrotizing enterocolitis (NEC) pathogenesis. β2 integrins regulate TLR signaling, and integrin β2 (ITGB2) deficiency causes TLR hyperresponsiveness. To test the hypothesis that ITGB2 genetic variants modulate NEC susceptibility, we sequenced the exonic ITGB2 locus to compare the prevalence of deleterious variants among 221 preterm infants with and without NEC. ITGB2 variants were not associated with NEC in our entire cohort (NEC [9/56] versus controls [16/165], P = 0.19) or in extremely low birthweight infants (ELBW, controls [7.9%] versus NEC [18.2%]; P = 0.11) but were increased compared to the populace (4.5%, gnomad.broadinstitute.org). Combined annotation-dependent depletion -predicted deleterious ITGB2 variants increased proportionately with increasing NEC severity in ELBW infants (controls [6.7%] versus medical NEC [16.7%] versus surgical NEC [19%] (P = 0.03). Although ITGB2 variants were not associated with NEC in our preterm cohort, subgroup analysis showed a trend towards enrichment with NEC severity in ELBW infants.

A piglet model of iatrogenic rectosigmoid hypoganglionosis reveals the impact of the enteric nervous system on gut barrier function and microbiota postnatal development

BACKGROUND

Hirschsprung-associated enterocolitis physiopathology likely involves disturbed interactions between gut microbes and the host during the early neonatal period. Our objective was to create a neonatal porcine model of iatrogenic aganglionosis to evaluate the impact of the enteric nervous system (ENS) on microbiota and intestinal barrier postnatal development.

METHODS

Under general anesthesia, the rectosigmoid serosa of 5-day-old suckling piglets was exposed to 0.5% benzalkonium chloride solution (BAC, n = 7) or saline (SHAM, n = 5) for 1 h. After surgery, animals returned to their home-cage with the sow and littermates and were studied 21 days later.

RESULTS

BAC treatment induced partial aganglionosis with absence of myenteric plexus and reduced surface area of submucosal plexus ganglia (-58%, P < 0.05) in one third of the rectosigmoid circumference. Epithelial permeability of this zone was increased (conductance +63%, FITC-dextran flux +386%, horseradish-peroxidase flux +563%, P < 0.05). Tight junction protein remodeling was observed with decreased ZO-1 (-95%, P < 0.05) and increased claudin-3 and e-cadherin expressions (+197% and 61%, P < 0.05 and P = 0.06, respectively). BAC piglets harbored greater abundance of proinflammatory bacteria (Bilophila, Fusobacterium) compared to SHAM in the rectosigmoid lumen.

CONCLUSIONS

This large animal model demonstrates that hypoganglionosis is associated with dramatic defects of gut barrier function and establishment of proinflammatory bacteria.

Postoperative enterocolitis assessment using two different cut-off values in the HAEC score in Hirschsprung patients undergoing Duhamel and Soave pull-through

Background

Hirschsprung-associated enterocolitis (HAEC) is the most severe and potentially lethal complication of Hirschsprung disease (HSCR) which might occur following definitive surgery. Our objectives were: 1) to compare the incidence of HAEC after Duhamel and Soave procedures using different cut-off values of the HAEC scoring method; and 2) to associate them with the risk factors, including sex, aganglionosis type, mothers’ age at childbirth, gestational age, and mothers’ educational level.

Methods

Medical records of patients with HSCR who underwent Soave and Duhamel procedures in our institution, Indonesia (January 2012 – December 2016) were reviewed retrospectively. Two cut-off values of the HAEC scoring system (i.e., ≥10 and ≥ 4) were utilized.

Results

Eighty-three patients with HSCR were recruited in this study (Soave: 37 males and 7 females vs. Duhamel: 28 males and 11 females; p = 0.18). The incidence of HAEC after surgery was 14/83 (16.9%) and 38/83 (45.8%) for cut-off values of ≥10 and ≥ 4, respectively (p = 0.00012), and tended to have an association with sex (p = 0.09). Although it was not statistically significant (p = 0.07), the frequency of HAEC after Soave procedure tended to be higher in patients with their mother’s age of ≤35 years at childbirth than those with their mother’s age of > 35 years (OR = 7.9; 95% CI = 0.9–72.1). Multivariate analysis indicated none of the risk factors were associated with the frequency of HAEC after definitive surgery.

Conclusions

The lower cut-off value of ≥4 might increase the possibility to diagnose HAEC, particularly the mild cases. The incidence of HAEC after definitive surgery was not associated with any risk factors in our cohort patients. Further multicenter studies with a larger sample size are necessary to confirm our findings.

Identification of gene coexpression modules, hub genes, and pathways related to spinal cord injury using integrated bioinformatics methods

Spinal cord injury (SCI) is characterized by dramatic neurons loss and axonal regeneration suppression. The underlying mechanism associated with SCI-induced immune suppression is still unclear. Weighted gene coexpression network analysis (WGCNA) is now widely applied for the identification of the coexpressed modules, hub genes, and pathways associated with clinic traits of diseases. We performed this study to identify hub genes associated with SCI development. Gene Expression Omnibus (GEO) data sets GSE45006 and GSE20907 were downloaded and the significant correlativity and connectivity between them were detected using WGCNA. Three significant consensus modules, including 567 eigengenes, were identified from the master GSE45006 data following the preconditions of approximate scale-free topology for WGCNA. Further bioinformatics analysis showed these eigengenes were involved in inflammatory and immune responses in SCI. Three hub genes Rac2, Itgb2, and Tyrobp and one pathway "natural killer cell-mediated cytotoxicity" were identified following short time-series expression miner, protein-protein interaction network, and functional enrichment analysis. Gradually upregulated expression patterns of Rac2, Itgb2, and Tyrobp genes at 0, 3, 7, and 14 days after SCI were confirmed based on GSE45006 and GSE20907 data set. Finally, we found that Rac2, Itgb2, and Tyrobp genes might take crucial roles in SCI development through the "natural killer cell-mediated cytotoxicity" pathway.

Advances in understanding the association between Down syndrome and Hirschsprung disease (DS-HSCR)

The clinical association between Trisomy 21 (Down syndrome) and aganglionosis (Hirschsprung disease; DS-HSCR) is well-established, being of the order of 5% and remains the most common congenital association with Hirschsprung disease. However, little consensus exists as to the possible etiologic and genetic factors influencing this association. Recent research has identified a number of levels at which development of the enteric nervous system is potentially affected in Trisomy 21. These include a decreased central pool of available neuroblasts for migration into the enteric nervous system, abnormal neuroblast type, poor synaptic nerve function and early germline gene-related influences on the migrating neuroblasts due to genetic mutations of a number of important developmental genes, and possible somatic mutations resulting from alterations in the local tissue microenvironment. In this paper, we review available evidence for this association. In addition, we provide evidence of both germline and somatic gene mutations suggesting causation. Although the picture is complex, recent associations between specific RET proto-oncogene variations have been shown to be significant in Down syndrome patients with Hirschsprung disease, as they probably interfere with vital RET functions in the development of the autonomic and enteric nervous systems, increasing the risk of disturbed normal function. In addition, we explore potential role of other facilitatory influence of other susceptibility genes as well as potential other chromosome 21 gene actions and the microenvironment on the Down syndrome gastro-intestinal tract. The various ways in which trisomy of chromosome influences the enteric nervous system are becoming clearer. The sum of these effects influences the outcome of surgery in Down syndrome patients with Hirschsprung Disease.

Identification of risk factors for postoperative recurrent Hirschsprung associated enterocolitis

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Novel Insights into the Pathogenesis of Hirschsprung's-associated Enterocolitis

Objective:

To systematically summary the updated results about the pathogenesis of Hirschsprung's-associated enterocolitis (HAEC). Besides, we discussed the research key and direction based on these results.

Data Sources:

Our data cited in this review were obtained mainly from PubMed from 1975 to 2015, with keywords “Hirschsprung enterocolitis”, “Hirschsprung's enterocolitis”, “Hirschsprung's-associated enterocolitis”, “Hirschsprung-associated enterocolitis”, “HAEC”, and “EC”.

Study Selection:

Articles regarding the pathogenesis of HAEC were selected, and the articles mainly regarding the diagnosis, surgical approach, treatment, and follow-up were excluded.

Results:

Several factors, mainly including mucus barrier, intestinal microbiota, and immune function, as well as some other factors such as genetic variations and surgical reasons, have been found to be related to the pathogenesis of HAEC. Changed quantity and barrier property of mucus, different composition of microbiota, and an abnormal immune state work together or separately trigger HAEC.

Conclusions:

The maintenance of intestinal homeostasis is due to a well cooperation of microbiota, mucus barrier, and immune system. If any part presents abnormal, intestinal homeostasis will be broken. Meanwhile, for patients with Hirschsprung's disease or HAEC, dysfunction of these parts has been found. Thus, the happening of HAEC may be mainly attributed to the disorders of intestinal microbiota, mucus barrier, and immune system.

Altered expression of IL36γ and IL36 receptor (IL1RL2) in the colon of patients with Hirschsprung's disease

PURPOSE

Hirschsprung's disease associated enterocolitis (HAEC) is the most common cause of morbidity and mortality in Hirschsprung's disease (HSCR). Altered intestinal epithelial barrier function and abnormal microbiota are implicated in the pathogenesis of HAEC. IL-36γ, a member of the IL-1 superfamily, is involved in host defense and contributes to proinflammatory responses and development of inflammatory diseases. The IL36 receptor (IL1RL2) is an important mediator molecule in the inflammatory response. Animal data suggests that IL1RL2 is involved in mucosal healing. We designed this study to investigate the hypothesis that the IL-36γ axis is altered in HSCR.

METHODS

We investigated IL-36γ and IL1RL2 expression in ganglionic and aganglionic bowel of HSCR patients (n = 10) and controls (n = 10). qPCR, Western blotting and confocal immunofluorescence were performed.

MAIN RESULTS

qPCR and Western blot analysis revealed that IL-36γ is strongly expressed in the aganglionic and ganglionic colon of patients with HSCR. ILR1L2 expression was significantly decreased in HSCR specimens compared to controls (p < 0.05). Confocal microscopy revealed a markedly increased expression of IL36γ in the colonic epithelium of patients with HSCR compared to controls. IL1RL2 was localized in the colonic epithelium and showed a markedly decreased expression in all HSCR specimens.

CONCLUSION

To our knowledge, we report for the first time the expression of IL36γ and ILRL2 in the colon of patients with HSCR. The increased expression of IL36γ and the markedly decreased expression of IL1RL2 in the aganglionic and ganglionic bowel in HSCR may result in an increased inflammatory response and altered mucosal response healing leading to the susceptibility to develop HAEC.

Characterization of Intestinal Microbiomes of Hirschsprung's Disease Patients with or without Enterocolitis Using Illumina-MiSeq High-Throughput Sequencing

Hirschsprung-associated enterocolitis (HAEC) is a life-threatening complication of Hirschsprung's disease (HD). Although the pathological mechanisms are still unclear, studies have shown that HAEC has a close relationship with the disturbance of intestinal microbiota. This study aimed to investigate the characteristics of the intestinal microbiome of HD patients with or without enterocolitis. During routine or emergency surgery, we collected 35 intestinal content samples from five patients with HAEC and eight HD patients, including three HD patients with a history of enterocolitis who were in a HAEC remission (HAEC-R) phase. Using Illumina-MiSeq high-throughput sequencing, we sequenced the V4 region of bacterial 16S rRNA, and operational taxonomic units (OTUs) were defined by 97% sequence similarity. Principal coordinate analysis (PCoA) of weighted UniFrac distances was performed to evaluate the diversity of each intestinal microbiome sample. The microbiota differed significantly between the HD patients (characterized by the prevalence of Bacteroidetes) and HAEC patients (characterized by the prevalence of Proteobacteria), while the microbiota of the HAEC-R patients was more similar to that of the HAEC patients. We also observed that the specimens from different intestinal sites of each HD patient differed significantly, while the specimens from different intestinal sites of each HAEC and HAEC-R patient were more similar. In conclusion, the microbiome pattern of the HAEC-R patients was more similar to that of the HAEC patients than to that of the HD patients. The HD patients had a relatively distinct, more stable community than the HAEC and HAEC-R patients, suggesting that enterocolitis may either be caused by or result in a disruption of the patient's uniquely adapted intestinal flora. The intestinal microbiota associated with enterocolitis may persist following symptom resolution and can be implicated in the symptom recurrence.

Established and Emerging Concepts in Hirschsprung’s-Associated Enterocolitis

Hirschsprung's disease (HSCR) is a common cause of neonatal bowel obstruction and the approach to diagnosis and surgical treatment is well defined and accepted. Hirschsprung's-associated enterocolitis (HAEC) remains a frequent cause of pre-operative and post-operative morbidity and mortality, with unchanged treatment guidelines over multiple decades. Recent advances in our understanding of the genetics underlying HSCR have allowed the development of animal models, some of which recapitulate the HAEC phenotype. These animal models, along with recent translational studies, have implicated multiple facets of mucosal immunity and microbiome dysbiosis in the development of HAEC. Here, we will review the established epidemiology, modes of diagnosis and treatment of HAEC. Furthermore, we will explore emerging concepts in the pathogenesis of this disease; including animal models, alterations in mucosal immunity, dysbiosis of the intestinal microbiome, specific genetic susceptibility, and novel treatment modalities.

Altered goblet cell differentiation and surface mucus properties in Hirschsprung disease

Hirschsprung disease-associated enterocolitis (HAEC) leads to significant mortality and morbidity, but its pathogenesis remains unknown. Changes in the colonic epithelium related to goblet cells and the luminal mucus layer have been postulated to play a key role. Here we show that the colonic epithelium of both aganglionic and ganglionic segments are altered in patients and in mice with Hirschsprung disease (HSCR). Structurally, goblet cells were altered with increased goblet cell number and reduced intracellular mucins in the distal colon of biopsies from patients with HSCR. Endothelin receptor B (Ednrb) mutant mice showed increased goblet cell number and size and increased cell proliferation compared to wild-type mice in aganglionic segments, and reduced goblet cell size and number in ganglionic segments. Functionally, compared to littermates, Ednrb^−/− mice showed increased transepithelial resistance, reduced stool water content and similar chloride secretion in the distal colon. Transcript levels of goblet cell differentiation factors SPDEF and Math1 were increased in the distal colon of Ednrb^−/− mice. Both distal colon from Ednrb mice and biopsies from HSCR patients showed reduced Muc4 expression as compared to controls, but similar expression of Muc2. Particle tracking studies showed that mucus from Ednrb^−/− mice provided a more significant barrier to diffusion of 200 nm nanoparticles as compared to wild-type mice. These results suggest that aganglionosis is associated with increased goblet cell proliferation and differentiation and subsequent altered surface mucus properties, prior to the development of inflammation in the distal colon epithelium. Restoration of normal goblet cell function and mucus layer properties in the colonic epithelium may represent a therapeutic strategy for prevention of HAEC.

Polymorphism of ITGB2 gene 3'-UTR+145C/A is associated with biliary atresia

BACKGROUND AND STUDY AIMS

Biliary atresia (BA) is a devastating disease of infants, invariably leading to cirrhosis, end-stage liver disease, and death if untreated. The etiology of BA is unknown, although infectious, immune, and genetic causes have been suggested. This study was designed to investigate whether polymorphism of the ITGB2 (CD18) gene is associated with susceptibility to BA.

METHODS

The ITGB2 gene promoter and 16 exons were genotyped following amplification and sequencing, with associations assessed using Fischer's exact test in 106 patients diagnosed with BA and 108 unrelated healthy controls.

RESULTS

We found one single nucleotide polymorphism (SNP) in the ITGB2 promoter region (-680 C/T) and five SNPs in exons, including: -111 T/C in exon 1, 117 G/A in exon 3, 819 G/A in exon 7, 1101 C/A in exon 10, and 3'-UTR+145C/A in exon 16. There were no significant differences in genotype and allelic frequencies of any of the SNPs between controls and patients with BA in both the promoter and exons 1, 3, 7, and 10. 3'-UTR+145C/A showed a significant increase in the C allele frequency (OR = 2.19, 95% CI: 1.39-3.46, p = 0.0006) and a significant increase in the CC genotype (p = 0.001) in BA patients compared with healthy controls. Using a reporter gene assay, the construct that contained the risk allele (3'-UTR+145 C) showed significantly higher luciferase activity than the nonrisk A allele (p = 0.007).

CONCLUSION

Our study provides the first evidence of a possible role of ITGB2 3'-UTR+145C/A polymorphism in the pathogenesis of BA.

Hirschsprung-associated enterocolitis: pathogenesis, treatment and prevention

Hirschsprung-associated enterocolitis (HAEC) is a common and sometimes life-threatening complication of Hirschsprung disease (HD). Presenting either before or after definitive surgery for HD, HAEC may manifest clinically as abdominal distension and explosive diarrhea, along with emesis, fever, lethargy, and even shock. The pathogenesis of HAEC, the subject of ongoing research, likely involves a complex interplay between a dysfunctional enteric nervous system, abnormal mucin production, insufficient immunoglobulin secretion, and unbalanced intestinal microflora. Early recognition of HAEC and preventative practices, such as rectal washouts following a pull-through, can lead to improved outcomes. Treatment strategies for acute HAEC include timely resuscitation, colonic decompression, and antibiotics. Recurrent or persistent HAEC requires evaluation for mechanical obstruction or residual aganglionosis, and may require surgical treatment with posterior myotomy/myectomy or redo pull-through. This chapter describes the incidence, pathogenesis, treatment, and preventative strategies in management of HAEC.

The pathogenesis of Hirschsprung's disease-associated enterocolitis

Hirschsprung's disease-associated enterocolitis (HAEC) remains the most life-threatening complication in Hirschsprung disease (HD) patients. The pathogenesis of HAEC has not been determined and many hypotheses regarding the etiology of HAEC have been proposed. These include a possible causal relationship between the abnormal enteric nervous system development in HD and the development of enterocolitis. Based on the complex genetic causes of HD that have been discovered and the resultant heterogeneous group of patients that exists, the causes of HAEC are likely multiple. New insights regarding the relationship of the role of the enteric nervous system and its interaction between intestinal barrier function, innate host immunity, and commensal microflora have been discovered, which may shed light on this perplexing problem. This review presents current known risk factors of HAEC and the proposed theories and supporting evidence for the potential etiologies of HAEC.

Clinical impacts of delayed diagnosis of Hirschsprung's disease in newborn infants

BACKGROUND

Asian infants are at a higher risk of having Hirschsprung's disease (HD). Although HD is surgically correctable, serious and even lethal complications such as Hirschsprung's-associated enterocolitis (HAEC) can still occur. The aim of this study was to investigate the risk factors of HAEC, and the clinical impacts of delayed diagnosis of HD in newborn infants.

PATIENTS AND METHODS

By review of medical charts in a medical center in Taiwan, 51 cases of neonates with HD between 2002 and 2009 were collected. Patients were divided into two groups based on the time of initial diagnosis: Group I, diagnosis made within 1 week after birth, and Group II after 1 week. Clinical features including demographic distribution, presenting features of HD, short-term and long-term complications related to HD were compared between the two groups of patients.

RESULTS

There were 25 patients in Group I and 19 in Group II. Group II patients had more severe clinical signs and symptoms of HAEC than Group I patients. The incidence of preoperative HAEC was 12% in Group I and 63% in Group II (adjusted odds ratio = 12.81, confidence interval = 2.60-62.97). Patients with preoperative HAEC were more likely to develop adhesive bowel obstruction after operation (33% vs. 3%, p = 0.013) and failure to thrive (33% vs. 3%, p = 0.013). Also, patients with long-segment or total colonic aganglionosis were at risk of developing both postoperative HAEC (85% vs. 29%, p = 0.001) and failure to thrive (39% vs. 3%, p = 0.002).

CONCLUSION

In our study, we found that delayed diagnosis of HD beyond 1 week after birth significantly increases the risk of serious complications in neonatal patients. Patients with long-segment or total colonic aganglionosis have higher risk of postoperative HAEC and failure to thrive. Patients with preoperative HAEC are more likely to have adhesive bowel obstruction and failure to thrive.

Intronic RET gene variants in Down syndrome-associated Hirschsprung disease in an African population

BACKGROUND

Clinical association between Hirschsprung disease (HD) and Down syndrome (DS) is well established. RET promoter and intron 1 variations have been shown to interfere with RET function, increasing the risk of HD pathogenesis. The intronic single-nucleotide polymorphism 2 (SNP2 [rs2435357]) has been associated with DS-associated HD (DS-HD). This study focuses on variations of specific RET intron, 1 SNPs (viz, SNP1 [rs2506004] and SNP2 [rs2435357]) in DS-HD.

PATIENTS AND METHODS

DNA was extracted from paraffin-embedded tissue samples and whole blood in 14 patients with DS with histologically proven HD. Polymerase chain reaction products of RET intron 1 were screened for genetic variation and matched to DS and controls from the general population.

RESULTS

Thirty-seven blood and/or tissue from 14 patients with DS-HD were investigated. RET intronic variations (SNP1 [rs2506004] or SNP2 [rs2435357]) were detected in all patients. SNP1 was detected in all patients, was heterozygous in 9, and homozygous in 5 samples (all aganglionic and 1 total colonic aganglionosis). SNP2 was absent in 6 patients, heterozygous in 6, and homozygous in 3. Three DS controls had a heterozygous SNP1. Homozygous intronic SNP RET variations were related to aganglionic tissue but not normally ganglionated or transitional zone from the same individual.

CONCLUSIONS

Potential disease-related RET mutations were identified in the intron region in 80% of patients with DS-HD investigated, suggesting a causal relationship. The presence of a homozygous form in the aganglionic tissue probably represents a somatic mutation, which suggests local microenvironmental factors in HD pathogenesis.

Motility problems in the intellectually challenged child, adolescent, and young adult

Gastrointestinal (GI) motility problems represent an important cause of morbidity and sometimes mortality in patients affected by developmental disorders. This article describes motility disorders in Down syndrome, cerebral palsy, familial dysautonomia, and Williams syndrome. These problems do not often receive appropriate attention, either because priority is given to other medical aspects of the disorder, or because of the inability of affected children to communicate their symptoms. A better approach to the diagnosis and treatment of GI disorders is required to improve quality of life and minimize morbidity and mortality among patients with developmental disorders.

Hematologically important mutations: leukocyte adhesion deficiency (first update)

Leukocyte adhesion deficiency (LAD) is an immunodeficiency caused by defects in the adhesion of leukocytes (especially neutrophils) to the blood vessel wall. As a result, patients with LAD suffer from severe bacterial infections and impaired wound healing, accompanied by neutrophilia. In LAD-I, mutations are found in ITGB2, the gene that encodes the β subunit of the β(2) integrins. This syndrome is characterized directly after birth by delayed separation of the umbilical cord. In the rare LAD-II disease, the fucosylation of selectin ligands is disturbed, caused by mutations in SLC35C1, the gene that encodes a GDP-fucose transporter of the Golgi system. LAD-II patients lack the H and Lewis Le(a) and Le(b) blood group antigens. Finally, in LAD-III (also called LAD-I/variant) the conformational activation of the hematopoietically expressed β integrins is disturbed, leading to leukocyte and platelet dysfunction. This last syndrome is caused by mutations in FERMT3, encoding the kindlin-3 protein in all blood cells that is involved in the regulation of β integrin conformation.

A novel isoform of the 8p22 tumor suppressor gene DLC1 suppresses tumor growth and is frequently silenced in multiple common tumors

The critical 8p22 tumor suppressor deleted in liver cancer 1 (DLC1) is frequently inactivated by aberrant CpG methylation and/or genetic deletion and implicated in tumorigeneses of multiple tumor types. Here, we report the identification and characterization of its new isoform, DLC1 isoform 4 (DLC1-i4). This novel isoform encodes an 1125-aa (amino acid) protein with distinct N-terminus as compared with other known DLC1 isoforms. Similar to other isoforms, DLC1-i4 is expressed ubiquitously in normal tissues and immortalized normal epithelial cells, suggesting a role as a major DLC1 transcript. However, differential expression of the four DLC1 isoforms is found in tumor cell lines: Isoform 1 (longest) and 3 (short thus probably nonfunctional) share a promoter and are silenced in almost all cancer and immortalized cell lines, whereas isoform 2 and 4 utilize different promoters and are frequently downregulated. DLC1-i4 is significantly downregulated in multiple carcinoma cell lines, including 2/4 nasopharyngeal, 8/16 (50%) esophageal, 4/16 (25%) gastric, 6/9 (67%) breast, 3/4 colorectal, 4/4 cervical and 2/8(25%) lung carcinoma cell lines. The functional DLC1-i4 promoter is within a CpG island and is activated by wild-type p53. CpG methylation of the DLC1-i4 promoter is associated with its silencing in tumor cells and was detected in 38-100% of multiple primary tumors. Treatment with 5-aza-2'-deoxycytidine or genetic double knockout of DNMT1 and DNMT3B led to demethylation of the promoter and reactivation of its expression, indicating a predominantly epigenetic mechanism of silencing. Ectopic expression of DLC1-i4 in silenced tumor cells strongly inhibited their growth and colony formation. Thus, we identified a new isoform of DLC1 with tumor suppressive function. The differential expression of various DLC1 isoforms suggests interplay in modulating the complex activities of DLC1 during carcinogenesis.

Hirschsprung's disease and the brain

A link between factors governing brain development and the development of the ENS is not surprising as both processes are largely controlled by the same or similar neural growth factors which are expressed at more or less in the same spatio-temporal time frame. Hirschsprung's disease (HSCR) occurs as an isolated phenotype in 70% of cases but is associated with other congenital abnormalities and syndromic phenotypes in the remainder, with CNS anomalies making up 6.78%. These associations may be underestimated and are possibly pathogenetically linked to genetic associations and probable gene-gene interaction. In this review we explore known syndromes and other ENS associations of HSCR, looking at possible pathogenetic associations. We point out that borderline cognitive abilities, attention-deficit disorders and possible epileptic seizures in Hirschsprung's patients should be fully investigated. We recognise that this group of patients remain a challenge from a clinical and functional management point of view, and suggest possible management guidelines.

Hirschsprung's disease in the neurologically challenged child

BACKGROUND

The association between Hirschsprung's disease (HSCR) and central nervous system (CNS) anomalies and syndromes is interesting because of similar developmental pathways. In addition to associated syndromes (e.g., Trisomy 21), these include brain anomalies, mental retardation and growth, ear and hearing deformities, eye hypoplasia, and craniofacial abnormalities, suggesting an neurocristopathy. This group of patients present with neurological challenges and have special challenges in management especially in the older child and adolescent.

METHODS

We retrospectively investigated 32 patients with significant HSCR-associated neurological challenges out of a local database of 555 HSCRs (6%). Data were analyzed with details of neurological problem, treatment, complications, and mortality. Long-term outcome was assessed clinically.

RESULTS

A total of 32 neurologically challenged children were studied. The male/female ratio was 1.7:1 and all ethnic groups were affected. Abnormalities and syndromes included Down (n = 16) and probable Mowat-Wilson (n = 2) syndromes. Other abnormalities included ophthalmic problems (n = 8), CNS and brain abnormalities (n = 8). Mortality (22%) was mostly related to enterocolitis, particularly in Trisomy 21, ophthalmic problems (n = 8), CNS and brain abnormalities (n = 8). Follow-up age range was 1-34 years (8 years, adolescence and beyond). The outcome was variable, concomitant medical problems were common. Several patients failed to achieve satisfactory continence.

CONCLUSION

The association of neurological difficulties in patients with HSCR presents many challenges. Management could involve the exploration and evaluation of alternative treatment choices.

Genomics approach to the analysis of bacterial communities dynamics in Hirschsprung's disease-associated enterocolitis: a pilot study

INTRODUCTION

The most invalidating and life-threatening complication in Hirschsprung's disease patients (HSCR) is Hirschsprung's disease-associated enterocolitis (HAEC). The mechanisms underlying enterocolitis have not been identified. The limited knowledge of the role of intestinal microflora is in part due to the complexity of the intestinal microbiome and to the limitation of cultivation-based technologies, given that less than 25% of the intestinal bacterial species can be cultured.

MATERIALS AND METHODS

We used amplified ribosomal DNA restriction analysis (ARDRA) with four different restriction enzymes to study variations of microflora composition of the stools of a selected HSCR patient in different clinical conditions (acute phase vs. remission).

RESULTS

We assessed a total of 15 stool specimens belonging to the same 3-year-old male patient suffering from HSCR, which were harvested during 4 HAEC episodes and remission phases. Restriction analysis showed that HAEC episodes seem to cluster together at ARDRA analysis, thus suggesting a sort of predisposing bacterial community for HAEC development and the need for a microflora equilibrium to maintain wellness.

CONCLUSIONS

This approach proved to be effective, useful and powerful in assessing microflora dynamics and indicated that the differences in microflora associated with acute HAEC or remission are likely to result from a combination of disease activity and different antibiotic therapies. ARDRA proved to be useful in discriminating disease versus remission. Our findings indicated that HAEC results from a change in the equilibrium between bacterial species or from altered discrimination of harmless from harmful microorganisms, challenging the definition of pathogenic and non-pathogenic species. Based on these results, we propose ARDRA as a rapid inexpensive tool to assess microflora dynamics during HAEC episodes.

Genetics of Hirschsprung disease and anorectal malformations

Hirschsprung disease (HD) and anorectal malformations (ARMs) result from alterations in hindgut development. It has long been recognized that both recur in families and thus result, at least in part, from genetic factors. Progress in the understanding of the genetic basis of HD has been made by the application of findings from genetic animal models of altered enteric nervous system development to human beings. Several genes have been shown to be important for human enteric nervous system development, and current work is progressing to identify genetic interactions that may explain the variable phenotype of HD. By contrast, understanding of the genetic factors underlying ARMs is much less developed. We and others have shown that genetic factors play an important role in the pathogenesis of ARMs, and many mouse genetic models suggest molecular pathways that may be altered in ARMs.

Clinical features of Hirschsprung's disease associated with Down syndrome: a 30-year retrospective nationwide survey in Japan

PURPOSE

To identify the clinical features in diagnosis and treatment of Hirschsprung's disease (HD) associated with Down syndrome (DS), the authors retrospectively analyzed data for patients with DS from the past 3 nationwide surveys in Japan. This survey was already approved by the Japanese Society of Pediatric Surgeons.

METHODS

Patient data were collected in 3 phases-phase I (1978-1982), n = 47; phase II (1988-1992), n = 79; and phase III (1998-2002), n = 90. In total, data on 216 patients (5.6%) of 3852 were collected and analyzed.

RESULTS

The incidence of DS in patients with HD was 2.9%, 7.1%, and 8.2% in phases I, II, and III, respectively, with a corresponding male/female ratio of 5:1, 2.4:1, and 5:1. The ratio of the extent of aganglionosis was nearly consistent across all phases. In phases I, II, and III, the incidence of total colonic aganglionosis was 2.1%, 0%, and 2.2%; and that of cardiovascular anomalies, 36.1%, 45.6%, and 55.6%; and that of preoperative enterocolitis, 31.0%, 26.6%, and 24.4%. The 2 most common surgical procedures were the Soave procedure, including transanal endorectal pull-through, and Duhamel procedure including Z-shaped anastomosis. The mortality rate decreased over time, from 26.1% in phase I to 11.4% in phase II and 7.8% in phase III. Almost all mortality cases were associated with cardiovascular anomalies: 54.5%, 62.5%, and 85.7% in phases I, II, and III, respectively.

CONCLUSIONS

The incidence of HD with DS has increased over time. The number of male patients and cardiac anomalies has also increased in the last 10 years. Total colonic aganglionosis was rare. A marked decrease in the overall mortality rate was observed.

Down syndrome and the enteric nervous system

Down syndrome (DS) is the most common chromosomal abnormality occurring in humans. Up to 77% of DS children have associated gastrointestinal (GI) abnormalities, which may be structural or functional in nature. Functional disturbances may, in turn, affect the outcome of corrective surgical procedures, prompting to caution. It is becoming clear that the processes affecting the enteric nervous system (ENS) in DS not only affect the micro-anatomy but also nerve function, and there is some histological evidence of ENS variations in both human and DS animal models. This suggests that developmental disorders of the ENS are probably fundamental to the functional GI disturbances encountered in patients with DS. The anomalous brain development, function and resulting intellectual impairment associated with DS appears to result from the genetic imbalance created by the trisomy of chromosome 21. The possible links between the brain, GI and ENS involvement are not as yet entirely clear. Neurotropic factors affecting brain development during embryogenesis are probably interlinked with ENS development, but the precise mechanism of how this occurs has yet to be established. This study explores what is known about the ENS dysfunction in DS and reviews the possible importance of chromosome 21 located and other genes in its etiology. Functional motor disturbances of the esophagus and colon are not uncommon and may be congenital or acquired in nature. The most prominent of these include esophageal dysmotility syndromes (e.g. achalasia, gastroesophageal reflux, dysphagia) as well as a higher incidence of chronic constipation and Hirschsprung's disease (HSCR) (2-15%) occurring in association with DS. Chromosome 21 itself is thought to be the site of a modifier gene for HSCR. Recently identified candidate genetic mechanisms provide unique insights into the genetic background of the neurological and cognitive disorders associated with DS. Although the role of the triplicated chromosome 21 and genetic dosage remain important, the additional role of other chromosome 21 genes in the etiology of ENS developmental anomalies remains undetermined and requires ongoing research.