Disruptions of the intestinal microbiome in necrotizing enterocolitis, short bowel syndrome, and Hirschsprung's associated enterocolitis

Ileocecal valve-preservation ileocecostomy (IVPI) in infants with extremely short distal ileum after primary stoma

PURPOSE

Preserving the ileocecal valve (ICV) has shown significant benefits. We present our experience with 18 infants who underwent ileocecal valve-preservation ileocecostomy (IVPI) with an extremely short distal ileum after primary ileostomy.

METHODS

A retrospective analysis was conducted on IVPI cases between 2014 and 2020. Medical records were reviewed, including birth weight, age, primary diseases, length of ileus stump, surgical time and procedure, time to enteral feeding, postoperative hospital stay, and complications.

RESULTS

Eighteen patients (male: female = 12:6, median birth weight 1305 (750-4000) g, median gestational age 29 + 5 (27 + 6-39 + 6) weeks) were included in the analysis. Causes of surgery included necrotizing enterocolitis (13), ileocecal intestinal atresia (1), ileum volvulus (2), meconium peritonitis (1), and secondary intestinal fistula (1). The median corrected age of ileostomy closure was 3.2 months (2.0-8.0 months). The distance from the distal ileal stoma to the ICV ranged from 0.5 to 2 cm. The median length of the residual bowel was 90 cm (50-130 cm). ICV-plasty was performed in 3 cases due to secondary ICV occlusion or stenosis. All patients resumed feeding within 6 to 11 days after surgery. The postoperative hospital stay ranged from 12 to 108 days (median: 16.5 days). Complications included incisional infections in 2 cases, anastomotic stricture and adhesive ileus in 1 case, nosocomial sepsis and septic shock in 1 case. All children showed normal growth and development during a 6-65 month follow-up.

CONCLUSIONS

IVPI is safe and feasible for infants with an extremely short distal ileal stump. ICV-plasty could be applicable for cases with ileocecal occlusion/stenosis.

Is choline deficiency an unrecognized factor in necrotizing enterocolitis of preterm infants?

We undertook this review to determine if it is plausible that choline or phosphatidylcholine (PC) deficiency is a factor in necrotizing enterocolitis (NEC) after two clinical trials found a dramatic and unexpected reduction in NEC in an experimental group provided higher PC compared to a control group. Sources and amounts of choline/PC for preterm infants are compared to the choline status of preterm infants at birth and following conventional nutritional management. The roles of choline/PC in intestinal structure, mucus, mesenteric blood flow, and the cholinergic anti-inflammatory system are summarized. Low choline/PC status is linked to prematurity/immaturity, parenteral and enteral feeding, microbial dysbiosis and hypoxia/ischemia, factors long associated with the risk of developing NEC. We conclude that low choline status exists in preterm infants provided conventional parenteral and enteral nutritional management, and that it is plausible low choline/PC status adversely affects intestinal function to set up the vicious cycle of inflammation, loss of intestinal barrier function and worsening tissue hypoxia that occurs with NEC. In conclusion, this review supports the need for randomized clinical trials to test the hypothesis that additional choline or PC provided parenterally or enterally can reduce the incidence of NEC in preterm infants. IMPACT STATEMENT: Low choline status in preterm infants who are managed by conventional nutrition is plausibly linked to the risk of developing necrotizing enterocolitis.

Metabolomic Alterations of Volatile Organic Compounds and Bile Acids as Biomarkers of Microbial Shifts in a Murine Model of Short Bowel Syndrome

Pediatric short bowel syndrome (SBS) is a rare condition characterized by a massive loss of the small intestine, leading to the inability to meet nutritional requirements without the use of parenteral or enteral supplementation. SBS causes profound alterations in the intestinal microbiome and metabolome. The aim of this study was a detailed assessment of the intestinal microbiome and metabolome in a murine model of SBS. We performed a 60% proximal small bowel resection versus a sham operation in C57BL/6 mice. Four weeks postoperatively, the microbial communities of different intestinal segments (jejunum, ileum, colon) and stool were assessed by 16S rRNA gene sequencing. Bile acids in serum and stool and volatile organic compounds (VOCs) in the fecal headspace were assessed using LC-MS and GC-MS techniques. The α-diversity of the different intestinal segments did not significantly differ between the two groups. β-diversity significantly differed between sham and SBS mice. While in the jejunum, Faecalibaculum was significantly increased in SBS animals, a significant reduction in Lactobacillus and Sporosarcina was detected in the ileum of SBS mice. In the colon of SBS mice, a significant decrease in Ruminococcaceae and a significant increase in Proteobacteria such as Faecalibaculum and Escherichia-Shigella were found. Serum levels of deoxycholic, taurocholic and taurochenodeoxycholic acids were significantly higher in the SBS group. Of the 29 VOCs tested, hexane, isoflurane and pentane were significantly higher in the SBS group, and pyrrole was significantly lower. We were able to show that SBS causes shifts in the murine intestinal microbiome and metabolome including serum BAs and fecal VOCs.

Overabundance of Veillonella parvula promotes intestinal inflammation by activating macrophages via LPS-TLR4 pathway

Hirschsprung’s disease-associated enterocolitis (HAEC) is the most common complication of Hirschsprung’s disease (HSCR). The microbiome pattern of intestinal flora in HAEC patients was significantly abnormal compared to that in HSCR patients. The overabundance of V. parvula was detected in the gut of HAEC patients. To elucidate the pathological mechanisms of the overabundance of V. parvula, we established and analyzed inflammatory models induced by LPS or single-bacterial strain transplantation in vivo. The transplantation of V. parvula induced inflammatory response in the colon of mice. Besides, we found that LPS from V. parvula can significantly impair the barrier function of colonic epithelial cells and then activate macrophages which impaired pacemaker function of interstitial cells of Cajal (ICCs). It was thus a vicious cycle, where the macrophage-related inflammation caused by V. parvula via LPS-TLR4 pathway damaged the intestinal motility, which further aggravated the intestinal flora dysbiosis and promoted the development of HAEC. Itaconic acid could break the vicious cycle by inhibiting the activation of macrophages. It could be a potential therapeutic strategy for HAEC patients with intestinal flora dysbiosis.

Enteric nervous system modulation of luminal pH modifies the microbial environment to promote intestinal health

The enteric nervous system (ENS) controls many aspects of intestinal homeostasis, including parameters that shape the habitat of microbial residents. Previously we showed that zebrafish lacking an ENS, due to deficiency of the sox10 gene, develop intestinal inflammation and bacterial dysbiosis, with an expansion of proinflammatory Vibrio strains. To understand the primary defects resulting in dysbiosis in sox10 mutants, we investigated how the ENS shapes the intestinal environment in the absence of microbiota and associated inflammatory responses. We found that intestinal transit, intestinal permeability, and luminal pH regulation are all aberrant in sox10 mutants, independent of microbially induced inflammation. Treatment with the proton pump inhibitor, omeprazole, corrected the more acidic luminal pH of sox10 mutants to wild type levels. Omeprazole treatment also prevented overabundance of Vibrio and ameliorated inflammation in sox10 mutant intestines. Treatment with the carbonic anhydrase inhibitor, acetazolamide, caused wild type luminal pH to become more acidic, and increased both Vibrio abundance and intestinal inflammation. We conclude that a primary function of the ENS is to regulate luminal pH, which plays a critical role in shaping the resident microbial community and regulating intestinal inflammation.

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.

Epigenome - A mediator for host-microbiome crosstalk

The interaction between the gut and its eventual trillions of microbe inhabitants during microbial colonization, represents a critical time period for establishing the overall health and wellbeing of an individual. The gut microbiome represents a diverse community of microbes that are critical for many physiological roles of the host including host metabolism. These processes are controlled by a fine-tuned chemical cross talk between the host and microbiota. Although the exact mechanisms behind this cross talk remains elusive, microbiota induced epigenetic mechanisms like DNA methylation and histone modifications may be key. This review presents our perspective on the epigenome as a mediator for host-microbiota cross talk, as well as methodology to study epigenetics, the role of dysbiosis in disease, and how the gut microbiome-host axis may be used in personal medicine.

Gut Mucosal and Fecal Microbiota Profiling Combined to Intestinal Immune System in Neonates Affected by Intestinal Ischemic Injuries

Background and Purpose: Early life microbiota plays a crucial role in human health by acting as a barrier from pathogens' invasion and maintaining the intestinal immune homoeostasis. Altered fecal microbiota (FM) ecology was reported in newborns affected by intestinal ischemia. Our purpose was to describe, in these patients, the FM, the mucosal microbiota (MM) and the mucosal immunity.

Methods: Fourteen newborns underwent intestinal resection because of intestinal ischemia. FM and MM were determined through targeted-metagenomics, diversity assignment and Kruskal-Wallis analyses of Operational taxonomic units (OTUs). The mucosal immune cells were analyzed through cytofluorimetry.

Results and Conclusion: Based on the severity intestinal injueris we identified two groups: extensive (EII) and focal intestinal ischemia (FII). FM and MM varied in EII and FII groups, showing in the EII group the predominance of Proteobacteria and Enterobacteriaceae and the reduction of Bacteroidetes and Verrucomicrobia for both microbiota. The MM was characterized by a statistically significant reduction of Bacteroides, Lachnospiraceae and Ruminococcaceae and by a higher diversity in the EII compared to FII group. FM showed a prevalence of Proteobacteria, while the Shannon index was lower in the EII compared to FII group. An overall increment in B- and T-lymphocytes and Natural killer (NK) T-like cells was found for EII mucosal samples associated to an increment of TNF-α and INF-γ expressing cells, compared to FII group. FM and MM carry specific signatures of intestinal ischemic lesions. Further research may be crucial to address the role of specific taxa in EII, expecially with reference to inflammation grade and ischemia extension.

Clostridium species as probiotics: potentials and challenges

Clostridium species, as a predominant cluster of commensal bacteria in our gut, exert lots of salutary effects on our intestinal homeostasis. Up to now, Clostridium species have been reported to attenuate inflammation and allergic diseases effectively owing to their distinctive biological activities. Their cellular components and metabolites, like butyrate, secondary bile acids and indolepropionic acid, play a probiotic role primarily through energizing intestinal epithelial cells, strengthening intestinal barrier and interacting with immune system. In turn, our diets and physical state of body can shape unique pattern of Clostridium species in gut. In view of their salutary performances, Clostridium species have a huge potential as probiotics. However, there are still some nonnegligible risks and challenges in approaching application of them. Given this, this review summarized the researches involved in benefits and potential risks of Clostridium species to our health, in order to develop Clostridium species as novel probiotics for human health and animal production.

First Report of Congenital Short Bowel Syndrome in an Iranian Patient Caused by a Mutation in the CLMP Gene

Congenital short bowel syndrome (CSBS) is a rare congenital neonatal disorder. CSBS results from intestinal impairment during embryogenesis. Mutated CXADR-like membrane protein ( CLMP ) and Filamin A genes are involved in the cause of CSBS. In this study, due to our misdiagnosis, we had to perform whole exome sequencing on the patient, and also we implemented cosegregation analysis on his parents with consanguineous marriage and also parents' mothers. We identified a homozygous loss of function mutation in the CLMP gene in exon 5 (c.664C > T, p.R222X). Also, both parents and grandmothers of the proband were heterozygous for this mutation. Loss of function mutation in CLMP causes CSBS, leading to impaired intestinal development.

Short bowel syndrome in children and adults: from rehabilitation to transplantation

Short bowel syndrome (SBS) is a dramatic clinical condition in both children and adults; the residual bowel length is not sufficient to avoid intestinal failure, with subsequent malnutrition and growth retardation, and intravenous support is required to provide the nutrients normally coming from the intestine. Apart from the primary disease, the medical status can be worsened by complications of intestinal failure: if there are irreversible, the prognosis is poor unless a successful intestinal rehabilitation is achieved. Areas covered: The rescue of the remnant small bowel requires a multidisciplinary expertise to achieve digestive autonomy. The use of intestinal trophic factors has shown encouraging results in improving the intestinal adaptation process. Whenever the residual bowel length is inadequate, in a well-selected population weaning parenteral nutrition (PN) off could be attempted by surgery through lengthening procedures. A further subset of patients, with total and irreversible intestinal failure and severe complications on PN, may have an indication to intestinal transplantation. This procedure is still affected by poor long-term results. Expert commentary: Novel approaches developed through a multidisciplinary team work, such as manipulation of microbiota or tissue bioengineering, should be added to current therapies to treat successfully SBS.

Fecal microbiota signatures of adult patients with different types of short bowel syndrome

BACKGROUND AND AIM

Short bowel syndrome (SBS) is a common cause of intestinal failure and can be divided into three types depending on intestinal anatomy. Gut dysbiosis has been observed in pediatric SBS patients and is associated with impaired outcome. Little is known about the changes in gut microbiota of adult SBS patients. Therefore, we aim to characterize the fecal microbiota of adult patients with different types of SBS.

METHODS

Fifteen fecal samples from healthy controls and adult patients with type II or type III SBS were collected (five in each group). Fecal microbial compositions were determined by high-throughput sequencing, and functional potential was predicted by Phylogenetic Investigation of Communities by Reconstruction of Unobserved States.

RESULTS

Bacterial α-diversity significantly decreased in SBS patients and positively correlated to the remaining small bowel length. SBS II patients were enriched with Proteobacteria but deficient in Firmicutes and Bacteroidetes. Whereas Lactobacillus and Prevotella dominated the microbiomes of SBS III patients, commensal bacteria from Lachnospiraceae, Ruminococcaceae, and Bacteroidaceae declined in SBS patients. The parenteral nutrition duration of SBS patients was positively related to the proportion of Enterobacteriaceae but negatively related to Lactobacillus. Functional pathways of citrate cycle and branched-chain and aromatic amino acid biosynthesis were abundant in SBS II patients, while functional profiles of pyrimidine and purine metabolism were dominant in SBS III patients.

CONCLUSIONS

Short bowel syndrome patients have a marked intestinal dysbiosis with type II SBS characterized by Proteobacteria and type III SBS featured by Lactobacillus, resulting in altered functional profiles of fecal microbiomes.

Bowel Function and Quality of Life After Transanal Endorectal Pull-through for Hirschsprung Disease: Controlled Outcomes up to Adulthood

OBJECTIVE

The aim of this study was to define controlled outcomes up to adulthood for bowel function and quality of life (QoL) after transanal endorectal pull-through (TEPT) for Hirschsprung disease (HD).

SUMMARY OF BACKGROUND DATA

Although TEPT is the surgical standard for HD, controlled long-term follow-up studies evaluating bowel function and QoL are lacking.

METHODS

Patients aged ≥4 years operated for HD with TEPT between 1987 and 2011 answered detailed questionnaires on bowel function and QoL [Pediatric Quality of Life Inventory (PedsQL, age <18 yrs) or Gastrointestinal Quality of Life Index (GIQLI) and SF-36]. Patients were compared with 3 age- and gender-matched controls each randomly selected from the general population.

RESULTS

Seventy-nine patients (64%) responded (median age 15, range 4-32 years; 86% rectosigmoid aganglionosis). Compared with controls, patients reported impairment of all aspects of fecal control (P < 0.05), except constipation. In cross-section, 75% of patients were socially continent (vs 98% of controls; P < 0.001). Soiling, fecal accidents, rectal sensation, and ability to withhold defecation improved with age to levels comparable to controls by adulthood (P = NS), but stooling frequency remained higher in 44% of patients (P < 0.05 vs controls). PedsQL domains in childhood were equal to controls (P = NS), except for proxy-reports of sadness/depression. Adults exhibited lower emotional scores, limitation of personal, and sexual relationships (P < 0.05).

CONCLUSION

Compared with matched peers, significant impairment of fecal control prevails after TEPT in HD patients during childhood, but symptoms diminish with age. Although overall QoL appeared comparable to controls, impairment of emotional and sexual domains may prevail in adulthood.

Pediatric short bowel syndrome and subsequent development of inflammatory bowel disease: an illustrative case and literature review

Short bowel syndrome (SBS) in neonates is an uncommon but highly morbid condition. As SBS survival increases, physiologic complications become more apparent. Few reports in the literature elucidate outcomes for adults with a pediatric history of SBS. We present a case report of a patient, born with complicated gastroschisis resulting in SBS at birth, who subsequently developed symptoms and pathologic changes of inflammatory bowel disease (IBD) as an adult. The patient lived from age 7, after a Bianchi intestinal lengthening procedure, to age 34 independent of parenteral nutrition (PN), but requiring hydration fluid via G-tube. He was then diagnosed with IBD, after presenting with weight loss, diarrhea, and malabsorption, which required resumption of PN and infliximab treatment. This report adds to a small body of the literature which points to a connection between SBS in neonates and subsequent diagnosis of IBD. Recent evidence suggests that SBS and IBD have shared features of mucosal immune dysfunction and altered intestinal microbiota. We review current treatment options for pediatric SBS as well as multidisciplinary and coordinated transition strategies. We conclude that there may be an etiologic connection between SBS and IBD and that this knowledge may impact outcomes and approaches to care.

The pediatric intestinal mucosal microbiome remains altered after clinical resolution of inflammatory and ischemic disease

BACKGROUND

The pediatric intestinal microbiome is impacted by many factors, including age, diet, antibiotics, and environment. We hypothesized that in operative patients, alterations to antibiotics and mechanoluminal stimulation would demonstrate measurable changes in the intestinal microbiome and that microbial diversity would be reduced without normal mechanoluminal stimulation and with prolonged antibiotic treatment.

METHODS

Bacterial 16s rRNA was extracted from swabbed samples of 43 intestines from 29 patients, aged 5 days to 13 years old. Swabs were obtained during initial resection or later stoma closure. Samples were compared using phylogenetic diversity whole tree alpha diversity and unweighted UniFrac distance beta diversity and by comparing significantly different taxonomic groups.

RESULTS

Microbial community structure varied significantly between obstructive and inflammatory diseases (P = .001), with an effect size of 0.99 (0.97, 1.00). This difference persisted even 6 weeks after return to health. Family Enterobacter and Clostridiaceae predominated in patients with necrotizing enterocolitis or focal intestinal perforation; patients with an obstructive pathology had an abundance of Bacteroides. Comparison of UniFrac distance between paired proximal and distal intestines demonstrated that paired samples were significantly closer than any other comparison.

CONCLUSION

In infants, inflammatory and ischemic intestinal pathologies treated with prolonged courses of antibiotics durably alter the intestinal mucosal microbiome. Diversion of mechanoluminal stimulation, however, does not.

Mechanisms of intestinal adaptation

Following loss of functional small bowel surface area due to surgical resection for therapy of Crohn's disease, ischemia, trauma or other disorders, the remnant gut undergoes a morphometric and functional compensatory adaptive response which has been best characterized in preclinical models. Increased crypt cell proliferation results in increased villus height, crypt depth and villus hyperplasia, accompanied by increased nutrient, fluid and electrolyte absorption. Clinical observations suggest that functional adaptation occurs in humans. In the immediate postoperative period, patients with substantial small bowel resection have massive fluid and electrolyte loss with reduced nutrient absorption. For many patients, the adaptive response permits partial or complete weaning from parenteral nutrition (PN), within two years following resection. However, others have life-long PN dependence. An understanding of the molecular mechanisms that regulate the gut adaptive response is critical for developing novel therapies for short bowel syndrome. Herein we present a summary of key studies that seek to elucidate the mechanisms that regulate post-resection adaptation, focusing on stem and crypt cell proliferation, epithelial differentiation, apoptosis, enterocyte function and the role of growth factors and the enteric nervous system.