Bacterial Microbiome Dynamics in Post Pull-Through Hirschsprung-Associated Enterocolitis (HAEC): An Experimental Study Employing the Endothelin Receptor B-Null Mouse Model

The mediating role of metabolites between gut microbiome and Hirschsprung disease: a bidirectional two-step Mendelian randomization study

Background

Gut microbiome (GM) was observed to be associated with the incidence of Hirschsprung disease (HD). However, the effect and mechanism of GM in HD is still unclear. To investigate the relationship between GM and HD and the effect of metabolites as mediators, a bidirectional two-step Mendelian randomization (MR) study was conducted.

Methods

The study selected instrument variables (IVs) from summary-level genome-wide association studies (GWAS). The MiBioGen consortium provided the GWAS data for GM, while the GWAS data for metabolites and HD were obtained from the GWAS Catalog consortium. Two-sample MR analyses were performed to estimate bidirectional correlations between IVs associated with GM and HD. Then, genetic variants related to 1,400 metabolite traits were selected for further mediation analyses using the Product method.

Results

This study found that seven genus bacteria had a significant causal relationship with the incidence of HD but not vice versa. 27 metabolite traits were significantly correlated with HD. After combining the significant results, three significant GM-metabolites-HD lines have been identified. In the Peptococcus-Stearoyl sphingomyelin (d18:1/18:0)-HD line, the Stearoyl sphingomyelin (d18:1/18:0) levels showed a mediation proportion of 14.5%, while in the Peptococcus-lysine-HD line, the lysine levels had a mediation proportion of 12.9%. Additionally, in the Roseburia-X-21733-HD line, the X-21733 levels played a mediation proportion of 23.5%.

Conclusion

Our MR study indicates a protective effect of Peptococcus on HD risk that is partially mediated through serum levels of stearoyl sphingomyelin (d18:1/18:0) and lysine, and a risk effect of Roseburia on HD that is partially mediated by X-21733 levels. These findings could serve as novel biomarkers and therapeutic targets for HD.

Children with Hirschsprung disease exhibited alterations in host-microbial co-metabolism after pull-through operation

PURPOSE

This study aims to compare the fecal metabolome in post pull-through HD with and without HAEC patients and healthy young children using nuclear magnetic resonance (NMR) spectroscopy.

METHODS

Fresh fecal samples were collected from children under 5 years of age in both post-pull-through HD patients and healthy Thai children. A total of 20 fecal samples were then analyzed using NMR spectroscopy.

RESULTS

Thirty-four metabolites identified among HD and healthy children younger than 5 years were compared. HD samples demonstrated a significant decrease in acetoin, phenylacetylglutamine, and N-acetylornithine (corrected p value = 0.01, 0.04, and 0.004, respectively). Succinate and xylose significantly decreased in HD with HAEC group compared to HD without HAEC group (corrected p value = 0.04 and 0.02, respectively). Moreover, glutamine and glutamate metabolism, and alanine, aspartate, and glutamate metabolism were the significant pathways involved, with pathway impact 0.42 and 0.50, respectively (corrected p value = 0.02 and 0.04, respectively).

CONCLUSION

Differences in class, quantity, and metabolism of protein and other metabolites in young children with HD after pull-through operation were identified. Most of the associated metabolic pathways were correlated with the amino acids metabolism, which is required to maintain intestinal integrity and function.

Intervention effects and related mechanisms of glycyrrhizic acid on zebrafish with Hirschsprung-associated enterocolitis

BACKGROUND

The prevention and treatment of Hirschsprung-associated enterocolitis (HAEC) is a serious challenge in pediatric surgery. Exploring the mechanism of HAEC is conducive to the prevention of this disease.

AIM

To explore the possible mechanism of glycyrrhizic acid (GA) and its therapeutic effect on HAEC.

METHODS

We developed a model of enteritis induced by trinitrobenzenesulfonic acid (TNBS) in zebrafish, and treated it with different concentrations of GA. We analyzed the effect of GA on the phenotype and inflammation of zebrafish.

RESULTS

After treatment with TNBS, the area of the intestinal lumen in zebrafish was significantly increased, but the number of goblet cells in the intestinal lumen was significantly reduced, but these did not increase the mortality of zebrafish, indicating that the zebrafish enteritis model was successfully developed. Different concentrations of GA protected zebrafish with enteritis. In particular, high concentrations of GA were important for the prevention and control of HAEC because it significantly reduced the intestinal luminal area, increased the number of goblet cells in the intestinal lumen, and reduced the levels of interleukin (IL)-1β and IL-8.

CONCLUSION

GA significantly reduced the intestinal luminal area, increased the number of intestinal goblet cells, and decreased IL-1β and IL-8 in zebrafish, and is important for prevention and control of HAEC.

Update on the Pathogenesis of the Hirschsprung-Associated Enterocolitis

Despite the significant progress that has been made in terms of understanding the pathophysiology and risk factors of Hirschsprung-associated enterocolitis (HAEC), the morbidity rate has remained unsatisfactorily stable, and clinical management of the condition continues to be challenging. Therefore, in the present literature review, we summarized the up-to-date advances that have been made regarding basic research on the pathogenesis of HAEC. Original articles published between August 2013 and October 2022 were searched in a number of databases, including PubMed, Web of Science, and Scopus. The keywords "Hirschsprung enterocolitis", "Hirschsprung's enterocolitis", "Hirschsprung's-associated enterocolitis", and "Hirschsprung-associated enterocolitis" were selected and reviewed. A total of 50 eligible articles were obtained. The latest findings of these research articles were grouped into gene, microbiome, barrier function, enteric nervous system, and immune state categories. The present review concludes that HAEC is shown to be a multifactorial clinical syndrome. Only deep insights into this syndrome, with an accrual of knowledge in terms of understanding its pathogenesis, will elicit the necessary changes that are required for managing this disease.

Risk factors for Hirschsprung-associated enterocolitis following Soave: a retrospective study over a decade

Background

Hirschsprung-associated enterocolitis (HAEC), one of the most significant causes of morbidity and mortality for patients with Hirschsprung disease (HSCR), can occur before and after radical surgery. This study aims to identify the risk factors for HAEC before and after Soave. 

Methods

A retrospective study of 145 patients with HSCR treated by transanal or combination with laparoscopic or laparotomy Soave procedure between January 2011 and June 2021 was performed. Data were retrieved from the medical records. HAEC was defined as the presence of clinical signs of bowel inflammation and requiring treatment with intravenous antibiotics and rectal irrigation for at least two days in the outpatient or inpatient department. Univariate analysis and multivariate regression models were used to identify risk factors for developing pre-and postoperative HAEC.

Results

The incidence of pre-and postoperative HAEC was 24.1% and 20.7%, respectively. More than 90% of the patients with the first episode of postoperative HAEC occurred within the first year after Soave. Long-segment aganglionosis was the independent risk factor for developing preoperative HAEC ([OR] 5.8, Cl 2.4–14.2, p < 0.001), while the history of preoperative HAEC was significantly associated with developing postoperative HAEC ([OR] 4.2, Cl 1.6–10.8, p = 0.003).

Conclusions

Long-segment aganglionosis was the independent risk factor for the development of preoperative HAEC, and the history of preoperative HAEC was strongly associated with developing HAEC after Soave.

Level of Evidence

Level III

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.

Mesona chinensis Benth Polysaccharides Alleviate DSS-Induced Ulcerative Colitis via Inhibiting of TLR4/MAPK/NF-κB Signaling Pathways and Modulating Intestinal Microbiota

SCOPE

Ulcerative colitis (UC) is a severe disease of the intestinal tract. To investigate the role of TLR4/Mitogen-activated protein kinase (MAPK)/Nuclear factor kappa-B(NF-κB) pathways and intestinal flora in UC, and the protective mechanisms of Mesona chinensis Benth polysaccharides (MBP), potential therapeutic agents due to their diabetes-relieving, cancer-suppressing, and immunomodulatory properties.

METHODS AND RESULTS

A dextran sulfate sodium (DSS)-induced mouse colitis model is used for experiments; the histopathology, immunohistochemistry, and Western blotting's results suggest that MBP can alleviate the colitis symptoms, inhibits the overproduction of TNF-α, IL-1β, promote IL-10, reduces myeloperoxidase activity, and alleviates the inflammatory response probably by inhibiting the activation of TLR4/MAPK/NF-κB pathways. Furthermore, MBP improvs the ratio of Bcl-2/BAX, maintains the intestinal integrity by promoting the levels of zonulin occludin-1 (ZO-1), occluding and mucin mucin-2 (MUC-2), reduces the levels of endotoxin (ET), lipopolysaccharide binding protein (LBP) in serum, and oxidative stress in liver. Moreover, using 16S rRNA Gene Sequencing analysis, MBP regulates gut microbiota by decreasing the abundances of Helicobacter and Prevotella and increasing the abundances of Lactobacillus and Coprococcus, reverses microbiota dysbiosis caused by DSS.

CONCLUSION

These findings confirm the anti-inflammatory effects of MBP, restoration of the intestinal barrier and intestinal flora, and have therapeutic potential to attenuate the development of UC.

E. coli JM83 damages the mucosal barrier in Ednrb knockout mice to promote the development of Hirschsprung‑associated enterocolitis via activation of TLR4/p‑p38/NF‑κB signaling

Hirschsprung-associated enterocolitis (HAEC) is characterized by intestinal mucosal damage and an imbalance in the intestinal microbiota. Recent studies have indicated that the TLR4/p-p38/NF-κB signaling pathway in the intestine is of great importance to intestinal mucosal integrity. The present study aimed to investigate the role of TLR4/phosphorylated (p-)38/NF-κB signaling in the pathogenesis of HAEC in E. coli JM83-infected endothelin receptor B (Ednrb)^−/− mice. Ednrb^−/− mice were infected with E. coli JM83 by oral gavage to establish the HAEC model. Wild-type and Ednrb^−/− mice were randomly divided into uninfected and E. coli groups. The role of TLR4/p-p38/NF-κB signaling was further evaluated by in vivo and in vitro analyses. The activation of the TLR4/p-p38/NF-κB signaling pathway induced by E. coli JM83 resulted in HAEC in Ednrb^−/− mice, which was evidenced by a significant increase in the expression of TNF-α, TGF-β and IL-10, and a decreased density of F-actin protein expression. TLR4 knockdown reduced the severity of enterocolitis and attenuated the expression of IL-10, TNF-α and TGF-β, whilst increasing the density of F-actin protein in Ednrb^−/− mice after E. coli infection. These results indicated that E. coli JM83 activates TLR4/p-p38/NF-κB signaling in Ednrb^−/− to promote the development of HAEC. Thus, inhibition of this signaling pathway may benefit the treatment and prevention of HAEC.

Pathways and microbiome modifications related to surgery and enterocolitis in Hirschsprung disease

BACKGROUND

Hirschsprung disease (HSCR) is a congenital anomaly of the enteric nervous system. Abnormal microbiome composition was reported in HSCR patients. In this study, we addressed and analyzed microbiome modifications with relation tosurgery and HSCR associated enterocolitis (HAEC).

METHODS

The faecal microbiome of 31 HSCR patients (overall 64 samples) was analyzed. HAEC was diagnosed and classified according to a combination of Pastor's and Elhalabi's criteria. Stool samples were analyzed by 16S sequencing (7 out of 9 polymorphic regions). Compositional and relative abundance profiles, as well as the functional potentials of the microbial community, were analyzed with the marker gene sequencing profiles using PICRUSt.

RESULTS

The relative abundance of Bacteroidetes showed a severe decrease with slow recovery after surgery. Conversely, Proteobacteria transiently increased their abundance. Noteworthy, a strong linkage has been found between Proteobacteria descendants and HAEC occurrences. The inferred functional analysis indicated that virulence factors and fimbriae or pili might be associated with HAEC.

CONCLUSIONS

Our study, addressing microbiome dynamics, demonstrated relevant changes after surgical manipulation. Alpha-diversity analyses indicated that surgery deeply affects microbiome composition. Proteobacteria and Enterobacteriaceae seem to play a pivotal role in HAEC occurrences. Several virulence factors, such as fimbriae or pili, might explain the HAEC-predisposing potential of selected microbiomes. These results suggest some innovative therapeutic approaches that deserve to be tested in appropriate clinical trials.

The Association of Altered Gut Microbiota and Intestinal Mucosal Barrier Integrity in Mice With Heroin Dependence

The gut microbiota is believed to play a significant role in psychological and gastrointestinal symptoms in heroin addicts. However, the underlying mechanism remains largely unknown. We show here that heroin addicts had a decrease in body mass index (BMI) and abnormal serum D-lactic acid (DLA), endotoxin (ET) and diamine oxidase (DAO) levels during their withdrawal stage, suggesting a potential intestinal injury. The gut microbial profiles in the mouse model with heroin dependence showed slightly decreased alpha diversity, as well as higher levels of Bifidobacterium and Sutterella and a decrease in Akkermansia at genus level compared to the control group. Fecal microbiota transplantation (FMT) further confirmed that the microbiota altered by heroin dependence was sufficient to impair body weight and intestinal mucosal barrier integrity in recipient mice. Moreover, short-chain fatty acids (SCFAs) profiling revealed that microbiota-derived propionic acid significantly decreased in heroin dependent mice compared to controls. Overall, our study shows that heroin dependence significantly altered gut microbiota and impaired intestinal mucosal barrier integrity in mice, highlighting the role of the gut microbiota in substance use disorders and the pathophysiology of withdrawal symptoms.

Alterations of Gut Bacteria in Hirschsprung Disease and Hirschsprung-Associated Enterocolitis

Hirschsprung-associated enterocolitis (HAEC) is a common life-threatening complication of Hirschsprung disease (HSCR). It has been proposed that gut microbiota, which have an essential role in gut-homeostasis, are associated with HAEC. Recent studies demonstrated an increase in alpha diversity of fecal microbiota over time in HSCR mice and a decrease in diversity after surgery. In addition, clinical studies have reported a reduction in bacterial richness in HSCR children after surgery. Some studies revealed a difference in microbiota between the proximal ganglionic and distal aganglionic intestine and found a difference in bacterial character between fecal and colonic specimens. HAEC studies found an increase in Proteobacteria, especially Escherichia and Enterobacteriaceae, with a decrease in Firmicutes and Bifidobacterium in HAEC patients. However, the direction of alpha diversity in HAEC patients is still controversial. The self-comparison of microbiota in treatment periods suggested that probiotics might improve gut dysbiosis and decrease the frequency of enterocolitis, but some reported contradictory findings. This review comprehensively summarizes and discusses key findings from animal and clinical data of the distinct microbiome associated with HCSR and the association of gut dysbiosis with the development of HAEC. This information should be useful in the establishment of novel interventions to improve gut dysbiosis and prevent enterocolitis in HSCR patients.

Predictive factors for the development of postoperative Hirschsprung-associated enterocolitis in children operated during infancy

PURPOSE

The risk factors for postoperative Hirschsprung-associated enterocolitis (HAEC) are still incompletely understood, especially age at which surgery is performed. Therefore, the aim of this study was to identify the risk factors for the development of postoperative HAEC in children operated during infancy.

METHODS

Thirty-five children who had undergone radical surgery for Hirschsprung disease (HD) during infancy were included in the study. They were divided into two groups; those who developed postoperative HAEC (HAEC, 14 patients) and those who did not (no HAEC, 21 patients). Their medical records were retrospectively reviewed for clinical details.

RESULTS

Developing postoperative HAEC was significantly associated with long-segment HD (p = 0.020) and the age at radical surgery (p = 0.0241). No other factors had a significant association with postoperative HAEC. In the patients who developed postoperative HAEC (n = 14), those with Trisomy 21 had significantly longer hospitalizations than those without. Patients with long-segment HD had a higher hospitalization rate than those with short-segment HD.

CONCLUSION

This study clearly showed that long-segment HD and older age at radical surgery are risk factors for developing postoperative HAEC.

Lipopolysaccharide upregulates miR-132/212 in Hirschsprung-associated enterocolitis, facilitating pyroptosis by activating NLRP3 inflammasome via targeting Sirtuin 1 (SIRT1)

Hirschsprung disease (HSCR) is a congenital disorder attributed to the failure of the neural crest derivatives migrating and/or differentiating along the hindgut. The most frequent complication in Hirschsprung disease patients is Hirschsprung-associated enterocolitis (HAEC). However, its pathogenesis has not been fully understood. This study investigated miRNAs influenced by Lipopolysaccharide (LPS) in postoperative HAEC patients, their effect on enterocolitis and the underlying mechanism. MiR-132 and miR-212 were up-regulated in HAEC dilated tissues and LPS-treated mice enteritis samples. LPS-stimulated HT29 cells showed a high expression of miR-132 and miR-212. QRT-PCR analysis, western blotting, luciferase reporter assay, and flow cytometric analysis were carried out in vitro, showing that miR-132 and miR-212 could directly inhibit Sirtuin 1 (SIRT1) expression. Consequently, SIRT1 deficiency in LPS-stimulated HT29 cell line and LPS-treated mice activated NLRP3 inflammasome and Caspase-1-mediated pyroptosis. Furthermore, the above inflammation activation was reversed by miR-132/212 inhibitor or SIRT1 overexpression plasmid transfection.In conclusion, LPS upregulated miR-132 and miR-212 expression in HAEC, suppressing SIRT1 and facilitating NLRP3 inflammasome activation, which induced pyroptosis. Our findings illustrated the role of LPS/miR-132/-212/SIRT1/NLRP3 regulatory network in the occurrence and progression of HAEC and proposed a new molecular pathway for LPS-mediated cell pyroptosis.

Reduced expression of the NLRP6 inflammasome in the colon of patients with Hirschsprung's disease

PURPOSE

Hirschsprung's associated enterocolitis (HAEC) is the most common cause of morbidity and mortality in Hirschsprung's Disease (HSCR). The pathogenesis of HAEC remains unsatisfactorily understood. Mounting evidence of an altered microbiome in patients with HSCR adds a new angle to the pathogenesis of HAEC. NLRP6 is a member of the nucleotide-binding domain, leucine-rich-repeat-containing (NLR) innate immune receptor family, a multiprotein complex that functions as a sensor of damage-associated molecular patterns. Known as inflammasomes they have been implicated in the regulation of colonic microbial ecology and by alteration, regulators of inflammation. We designed this study to test the hypothesis that NLRP6 expression is altered in the colon of patients with HSCR.

METHODS

We investigated NLPR6 protein expression in both the aganglionic and ganglionic regions of HSCR patients (n = 10) versus healthy control colon (n = 10). Protein distribution was assessed by using immunofluorescence and confocal microscopy. Gene and protein expressions were quantified using quantitative real-time polymerase chain reaction (qPCR), Western blot analysis, and densitometry.

MAIN RESULTS

qPCR and Western blot analysis revealed that NLRP6 is expressed in the colon of patients with HSCR. NLRP6 expression was significantly decreased (p < 0.003) in the ganglionic and aganglionic bowel in HSCR compared to controls. Confocal microscopy revealed that NLRP6 expression in colonic epithelium was markedly decreased in HSCR specimens compared to controls.

CONCLUSION

We demonstrate for the first time the expression and distribution of NLRP6 in patients with HSCR. The observed decreased expression of NLRP6 may contribute to an altered colonic microbiome in patients with HSCR and increases the susceptibility to develop HAEC.

A Metagenomics Study on Hirschsprung's Disease Associated Enterocolitis: Biodiversity and Gut Microbial Homeostasis Depend on Resection Length and Patient's Clinical History

Objectives: Since 2010, several researches demonstrated that microbiota dynamics correlate and can even predispose to Hirschsprung (HSCR) associated enterocolitis (HAEC). This study aims at assessing the structure of the microbiota of HSCR patients in relation to extent of aganglionosis and HAEC status. Methods: All consecutive HSCR patients admitted to Gaslini Institute (Genova, Italy) between May 2012 and November 2014 were enrolled. Institutional review board (IRB) approval was obtained. Stools were sampled and 16S rDNA V3-V4 regions were sequenced using the Illumina-MiSeq. Taxonomy assignments were performed using QIIME RDP. Alpha diversity indexes were analyzed by Shannon and Simpson Indexes, and Phylogenetic Diversity. Results: We enrolled 20 patients. Male to female ratio was 4:1. Six patients suffered from Total Colonic Aganglionosis (TCSA). Considering sample site (i.e., extent of aganglionosis), we confirmed the known relationship between sample site and both biodiversity and composition of intestinal microbiota. Patients with TCSA showed lower biodiversity and increased Proteobacteria/Bacteroidetes relative abundance ratio. When addressing biodiversity, composition and dynamics of TCSA patients we could not find any significant relationship with regard to HAEC occurrences. Conclusions: The composition of HAEC predisposing microbiota is specific to each patient. We could confirm that total colon resections can change the composition of intestinal microbiota and to dramatically reduce microbial diversity. The subsequent reduction of system robustness could expose TCSA patients to environmental microbes that might not be part of the normal microbiota. Future long-term studies should investigate both patients and their family environment, as well as their disease history.