Sacral Neural Crest-Independent Origin of the Enteric Nervous System in Mouse.

BACKGROUND & AIMS: The enteric nervous system (ENS), the gut's intrinsic nervous system critical for gastrointestinal function and gut-brain communication, is believed to mainly originate from vagal neural crest cells (vNCCs) and partially from sacral NCCs (sNCCs). Resolving the exact origins of the ENS is critical for understanding congenital ENS diseases but has been confounded by the inability to distinguish between both NCC populations in situ. Here, we aimed to resolve the exact origins of the mammalian ENS. METHODS: We genetically engineered mouse embryos facilitating comparative lineage-tracing of either all (pan-) NCCs including vNCCs or caudal trunk and sNCCs (s/tNCCs) excluding vNCCs. This was combined with dual-lineage tracing and 3-dimensional reconstruction of pelvic plexus and hindgut to precisely pinpoint sNCC and vNCC contributions. We further used coculture assays to determine the specificity of cell migration from different neural tissues into the hindgut. RESULTS: Both pan-NCCs and s/tNCCs contributed to established NCC derivatives but only pan-NCCs contributed to the ENS. Dual-lineage tracing combined with 3-dimensional reconstruction revealed that s/tNCCs settle in complex patterns in pelvic plexus and hindgut-surrounding tissues, explaining previous confusion regarding their contributions. Coculture experiments revealed unspecific cell migration from autonomic, sensory, and neural tube explants into the hindgut. Lineage tracing of ENS precursors lastly provided complimentary evidence for an exclusive vNCC origin of the murine ENS. CONCLUSIONS: sNCCs do not contribute to the murine ENS, suggesting that the mammalian ENS exclusively originates from vNCCs. These results have immediate implications for comprehending (and devising treatments for) congenital ENS disorders, including Hirschsprung's disease.

Extended total colonic aganglionosis and total intestinal aganglionosis: Challenging enemies.

AIM: Extended total colonic aganglionosis (ETCA) represents uncommon forms of Hirschsprung disease (HD), with aganglionosis extending into the proximal small bowel. ETCA management is challenging and associated with poor outcomes and high mortality. This study compares management and outcomes of ETCA to more common HD forms. METHODS: A retrospective cohort of HD patients (2012-2023) from two institutions. Three HD forms were compared: short-segment HD (SSHD, n = 19), long-segment HD or total colonic aganglionosis (LS/TCA, n = 9) and ETCA (n = 7). RESULTS: Normally innervated segments in ETCA patients ranged 0-70 cm. Median times to first surgery were; ETCA = 3 days versus TCA = 21 days (p = 0.017) and SSHD = 95 days (p < 0.001), respectively. Median number of surgeries were; ETCA = 4, versus TCA = 2 (p = 0.17) and SSHD = 1 (p = 0.002), respectively. All the patients underwent a definitive pull-through procedure, except four ETCA patients with a permanent jejunostomy and residual aganglionic segment of 57-130 cm. ETCA patients had 92% lower odds of enterocolitis (14%) compared to TCA patients (67%, p = 0.054), and comparable odds to SSHD patients (16%, p = 0.92). ETCA mortality was 14%. CONCLUSION: Extended total colonic aganglionosis patients require earlier and multiple interventions. Leaving an aganglionic segment may be advantageous, without increasing risk for enterocolitis. Tailored surgical treatment and rehabilitation programmes may prevent mortality and need for transplantation.

Surgical maneuvers for long-segment Hirschsprung pull-through in unique patients.

PURPOSE: Patients with Hirschsprung disease affecting the splenic flexure or more proximal segments present a surgical challenge. Mobilizing the transverse colon to the pelvis during a pull-through may obstruct the distal ileum, or the length may be insufficient to reach the lower pelvis. This retrospective study aimed to describe two surgical techniques that facilitate mobilization of the transverse colon and their outcome. METHODS: We included patients operated on between April 2017 and April 2024 and analyzed sex, comorbidities, type of pull- through, age at pull-through, history of previous surgeries, cause of the proximal transverse colon pull-through, technique used (Deloyers or Turnbull), complications , postoperative outcome and follow-up. The first technique used was the maneuver described by Turnbull. This operation creates a mesenteric defect and mobilizes the colon into this mesenteric window at the distal ileum level. The second technique was described by Deloyers and involves a 180-degree rotation of the right colon by dissecting the right colon attachment and the hepatocolic ligament. The cecum and the ileocecal valve are placed in the right upper quadrant, and the distal colon is mobilized into the pelvis. RESULTS: We included 13 patients, 12 boys and 1 girl. Eight patients had previous surgeries in another hospital: five had an initial transverse colostomy, and three had an ileostomy. The remaining five had the initial operation in our hospital: two had an ileostomy, two had a colostomy, and one had a primary pull-through. The median age at pull-through was 16 months (4-59 months). We used the Turnbull technique in four patients whose aganglionosis was limited to the middle transverse colon. The Deloyers technique was used in the remaining patients, with ganglion cells in the proximal transverse colon. We left a protective ileostomy in five patients. The median follow-up was 4.5 years (3 months to 10 years). The stoma takedown is pending in one patient. CONCLUSION: The Turnbull and Deloyers techniques were helpful in patients with aganglionosis affecting the transverse colon.

Skipped Aganglionic Lengthening Transposition (SALT) is highly effective to achieve enteral autonomy in selected patients with intestinal failure secondary to total intestinal aganglionosis.

BACKGROUND: Intestinal Failure, parenteral nutrition (PN) dependence, and subsequent liver disease are the most challenging and life-threatening complications of short bowel syndrome experienced by patients with total intestinal aganglionosis. Skipped Aganglionic Lengthening Transposition (SALT) showed to be a promising procedure to overcome such problems. We herein report the results of two patients who underwent SALT at the Umberto Bosio Center for Digestive Diseases. PATIENTS AND METHODS: Between November 2019 and July 2022, 2 patients with total intestinal aganglionosis underwent SALT as autologous intestinal lengthening procedure. Perioperative data and long-term outcomes are reported. Patient #1-A 18 month-old male (PN dependant) with 30 cm of ganglionated bowel at birth experienced a 35% increase of intestinal length after SALT (from 43 to 58 cm) thanks to three 5 cm interposed aganglionic loops. Postoperative course was uneventful and he was totally weaned by PN after 28 months postoperatively. He is without PN only receiving enteric feeding 53 months after the procedure. Patient #2-A 11 year-old female (PN dependant) with 100 cm of ganglionated jejunum underwent SALT at 11 years and experienced a 19% increase of bowel length thanks to four 5 to 7 cm interposed aganglionic loops. Postoperatively she required excision of two out of the four loops due to severe strictures and inadequate perfusion with a subsequent overall 10% increase of length after SALT. Of note, she improved significantly with a progressive reduction of PN that has been stopped after 18 months. CONCLUSION: Skipped aganglionic lengthening transposition (SALT) seems to be very effective in improving nutrients absorption in patients with total intestinal aganglionosis by increasing absorptive bowel surface and decelerating intestinal flow for a longer and more effective contact of enteric material with ileal mucosa. Provided these impressive results are confirmed in the very long-term, SALT could become a valid alternative for the treatment of patients with total intestinal aganglionosis carrying at birth at least 20 to 30 cm of ganglionated jejunum.

RET overactivation leads to concurrent Hirschsprung disease and intestinal ganglioneuromas.

Appropriately balanced RET signaling is of crucial importance during embryonic neural crest cell migration, proliferation and differentiation. RET deficiency, for example, leads to intestinal aganglionosis (Hirschsprung disease), whereas overactive RET can lead to multiple endocrine neoplasia (MEN) syndromes. Some RET mutations are associated with both intestinal aganglionosis and MEN-associated tumors. This seemingly paradoxical occurrence has led to speculation of a 'Janus mutation' in RET that causes overactivation or impairment of RET activity depending on the cellular context. Using an intestinal catenary culture system to test the effects of GDNF-mediated RET activation, we demonstrate the concurrent development of distal colonic aganglionosis and intestinal ganglioneuromas. Interestingly, the tumors induced by GDNF stimulation contain enteric neuronal progenitors capable of reconstituting an enteric nervous system when transplanted into a normal developmental environment. These results suggest that a Janus mutation may not be required to explain co-existing Hirschsprung disease and MEN-associated tumors, but rather that RET overstimulation alone is enough to cause both phenotypes. The results also suggest that reprogramming tumor cells toward non-pathological fates may represent a possible therapeutic avenue for MEN-associated neoplasms.

Reoperation for Hirschsprung Disease: Two cases of Vanishing Ganglion Cells and Review of the Literature.

Hirschsprung disease (HD) is characterized by circumferential aganglionosis of the rectum with variable proximal bowel involvement. The underlying pathogenesis is due to failure of caudal migration of neural crest cells during pre-natal development, causing functional bowel obstruction. Definitive therapy is surgical resection; however, a subset of patients will require reoperation. An important cause of reoperation is the rare but distinct entity described as the ganglion cell "vanishing" phenomenon. In this phenomenon, affected patients have normal circumferential ganglion cells present at the proximal margin during primary resection. They undergo a variable asymptomatic period post-primary resection but ultimately develop recurrent symptoms. Upon reoperation, ganglion cells seemingly vanish and are no longer present in the previously functioning and ganglionated bowel proximal to the initial anastomotic site. To further characterize and investigate this poorly understood pathology, here we present 2 cases of HD patients who required reoperation. Our small series implicates that an immune component may contribute as patient 2 had a brisk neurotrophic eosinophilic infiltrate only present in the reoperation specimen. However, this was not observed in patient 1. Other possible etiologies include post-operative ischemia/hypoxia, visceral neuropathy, or signaling abnormalities within the residual ganglion cells themselves.

Genetics of Hirschsprung's disease.

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

Rectal biopsy: is it really necessary in anorectal malformations?

AIM OF THE STUDY: The coexistence of Hirschsprung's disease (HD) with anorectal malformation (ARM) is rare but many surgeons still ask pathologists to look for ganglia in the terminal rectum or fistula. In this study, we aimed to highlight the rarity of this association and question the necessity of histological evaluation. METHODS: After obtaining board review approval, rectal specimens of ARM patients who underwent corrective surgery in the last 8 years were re-analyzed by two blinded pathologists for the presence and structure of ganglia. Clinical and radiological data of patients retrieved from center records and correlated with histopathologic findings. MAIN RESULTS: 67 patients with ARM were identified, distal rectal specimen was obtained in 47. The median age at the time of surgery was 11 months (2 days-59 months). A normal pattern of ganglia was present in 51.1% (24/47), 29.7% (14/47) had aganglionosis and 19.1% (9/47) were inconclusive due to insufficient material. None of the aganglionic specimens showed other histological findings of HD. Patients were followed up regularly in the outpatient colorectal clinic for a median of 87 months (42-117 m). Only 6 experienced severe constipation (3 ganglionic, 2 no biopsy, 1 aganglionic), all of whom responded to a bowel management program, and none developed other manifestations of HD (abdominal distension, failure to thrive or enterocolitis) or required additional surgery. CONCLUSIONS: Our results strongly suggest that the association of ARM and HD is extremely rare and the practice of searching for ganglia in the distal rectum or fistula of ARM patients should be discouraged to avoid potential misdiagnosis and overtreatment.

Submucosal Nerve Diameter in the Rectum Increases With Age: An Important Consideration for the Diagnosis of Hirschsprung Disease.

INTRODUCTION: Hypertrophic submucosal nerves, defined as ≥40 µm in diameter, are considered supportive of a diagnosis of HSCR, but the effect of age on nerve diameter has not been well-studied. We sought to determine the distribution of the largest nerve diameter in ganglionic rectal biopsies and the significance of hypertrophic submucosal nerves in the diagnosis of Hirschsprung disease (HSCR) based on age. METHODS: Rectal biopsies performed in the evaluation of HSCR were retrospectively reviewed from 179 patients (151 ganglionic biopsies, 28 aganglionic biopsies), and the diameter of the largest submucosal nerve was measured. RESULTS: In non-Hirschsprung disease (non-HSCR) biopsies, submucosal nerve diameter increased with age. In patients <1 year, the average diameter was 34.1 ± 11.6 µm but increased to 50.8 ± 17.3 µm after 1 year of age. Submucosal nerves ≥40 µm in diameter were significantly associated with HSCR across all ages [HSCR = 25/28 (89.3%) vs non-HSCR = 59/151 (39.1%), p < 0.0001] and remained significant in patients <1 year of age [HSCR = 22/24 (91.7%) vs non-HSCR = 19/91 (20.9%), p < 0.0001]. CONCLUSIONS: The diameter of submucosal nerves increases with age, and ≥40 µm nerves are common after 1 year of age.

Characterization of the Transition Zone in Short Segment Hirschsprung Disease Using Calretinin Immunostaining.

Introduction: The detailed expression pattern of calretinin immunohistochemistry in the transition zone (TZ) of Hirschsprung disease (HSCR) has not yet been reported. This study aims to examine the value of calretinin immunohistochemistry for more accurately determining the distal and proximal border of the TZ in short segment HSCR. Methods: Specimens of pull-through surgery from 51 patients with short form of HSCR were analyzed on two longitudinal strips using hematoxylin and eosin (H&E) staining and calretinin immunohistochemistry. Results: In all but two patients, the first appearance of calretinin expression was seen on mucosal nerve fibers before the appearance of any ganglion cells, indicating the distal border of the TZ. The maximum distance between the distal border of the TZ and the proximal border of the TZ, defined by ganglion cells in a normal density on H&E stained sections, a strong calretinin expression on mucosal nerve fibers and in >80% of submucosal and myenteric ganglion cells, with no nerve hypertrophy and absence of ganglionitis was 60 mm. Conclusion: The distal border of the TZ is characterized by calretinin positive intramucosal neurites in nearly all of short form of HSCR and not by calretinin expression on ganglion cells.

Histopathological dimensions differ between aganglionic and ganglionic bowel wall in children with Hirschsprung's disease.

BACKGROUND: In the validation of new imaging technology for children with Hirschsprung's disease (HSCR), basic anatomical parameters of the bowel wall must be established specifically for this patient group. AIM: To explore differences in histoanatomical layers of bowel wall, comparing ganglionic and aganglionic bowel walls, and to examine if the bowel wall thickness is linked to patient weight. METHODS: This was an observational study of bowel specimens from children weighing 0-10 kg, operated on consecutively during 2018-2020. Ganglionic and aganglionic bowel walls were measured in digitalized microscopy images from 10 sites per trans-sectional specimen and compared regarding the thickness of their histoanatomical layers. RESULTS: Bowel walls were measured in 21 children. Full bowel wall thickness did not differ between aganglionic and ganglionic bowel (2.20 vs 2.04; p = 0.802) while weight at surgery correlated positively with both ganglionic and aganglionic bowel wall thickness (r = 0.688 and 0.849, respectively), and age at surgery with ganglionic bowel wall thickness (r = 0.517). In aganglionic segments, the muscularis externa layer was thicker compared to that in ganglionosis (0.45 vs 0.31 mm, p = 0.012) whereas the muscularis interna was thinner (0.45 vs 0.62 mm, p < 0.001). A diagnostic index was identified whereby a lower ratio of muscularis interna/externa thickness followed by a thinner muscularis interna differed between aganglionic and ganglionic bowel in all specimens. CONCLUSION: Thicknesses of the bowel wall's muscle layers differ between aganglionic and ganglionic bowel walls in children with HSCR. These findings support a diagnostic index that could be validated for transfer to instant diagnostic imaging techniques. LEVEL OF EVIDENCE: Diagnostic: 3.

Translational research in Hirschprung's disease at the National Children's Research Centre in Dublin.

Hirschsprung's disease (HD) is a congenital condition characterised by aganglionosis in the distal bowel. Over the years, at the National Children's Research Centre (NCRC), HD has been one of the most prominent and successful research areas for Prof. Prem Puri's research team. Research fellows from around the world came to the NCRC to work on both animal and human studies of HD and, cumulatively, made important discoveries in this field, publishing a total of 144 HD articles in peer-reviewed journals. Through their published work, the NCRC has been recognised as the leading international centre for the investigation of HD and its allied disorders. In this review, I will summarise the main findings from this work.

Changes in postoperative quality of life of pediatric total colonic aganglionosis patients: effect of pull-through technique.

AIM: To assess mid-/long-term quality of life (QOL) of total colonic aganglionosis (TCA) patients. METHODS: Modified pre-existing QOL assessment tools for general lifestyle (GL), bowel function (BF), and mental health (MH) were administered to postoperative TCA patients from five institutions, who were at least 7 years old to compare Duhamel (with pouch) and Swenson/Soave (without pouch) techniques between children (Ch 7-12 years old), teenagers (Tn 13-19), and adults (Ad 20 and over). For MH, caregivers were also interviewed, but separately. Maximum scores were 12 for GL/MH and 18 for BF. RESULTS: There were 32 subjects. GL and BF scores increased significantly from Ch (GL 4.8 ± 2.5, BF: 11.3 ± 4.6) to Tn (GL 7.8 ± 2.6, BF 16.2 ± 3.0); scores for MH did not change significantly. Mean caregiver MH scores were significantly lower than mean subject MH scores for all age groups (subject scores: 10.1, 10.7, 10.7 versus caregiver scores: 6.8, 7.8, 8.1 for Ch, Tn, Ad, respectively). PT technique/presence of a pouch did not influence the incidence of enterocolitis or QOL scores. CONCLUSION: MH responses showed subjects felt better than caregivers believed. This discrepancy could cause conflict despite steadily improving GL/BF. QOL was unaffected by PT technique/presence of a pouch.

Do adult patients with congenital colorectal conditions know their diagnosis?

PURPOSE: Limited research exists about the knowledge that adult patients have about their congenital colorectal diagnosis. METHODS: This was an IRB approved, prospective study of patients in the Adult Colorectal Research Registry who completed surveys between October 2019 and March 2022. Surveys were administered through REDCap after patients consented to being contacted for research purposes. Patients provided demographic data, which was linked to surgical records, and the diagnoses provided by patients were compared with diagnoses recorded by the original surgeons. RESULTS: One hundred and thirty-one questionnaires were collected, 115 patients had anorectal malformations (ARM) and 16 had Hirschsprung disease (HD). Seven patients who had ARM were unaware that they had an ARM or HD. The type of ARM recorded by the surgeon was unavailable for comparison with the patient's reported diagnosis in four cases. Of the 111 remaining patients with ARM, only 32 of them (29%) knew what their own type of anomaly was. Female patients recalled their diagnosis more often than male patients (42.4% vs 13.5%). All 16 participants with HD correctly identified their diagnosis severity as HD with or without total colonic aganglionosis. CONCLUSION: The results of this study demonstrate patient's limited understanding of their type of ARM and highlight the urgent need to enhance communication and education strategies, such as issuing patients with medical diagnosis identification cards. It is critical for clinicians to better communicate with patients to ensure that they and their relatives truly understand their precise diagnosis. Adequately informed patients can better advocate for themselves, adhere to treatments and precautionary recommendations and navigate the complexities of transitional care. Consequently they can more effectively manage their lifelong complications.

Sonographic findings of total colonic aganglionosis in a neonate with Haddad syndrome: A case report.

Haddad syndrome is a rare congenital disorder characterized by congenital central hypoventilation syndrome and Hirschsprung disease. Total colonic aganglionosis is a rare and long-segment form of Hirschsprung disease, which is primarily diagnosed using contrast enemas. However, the diagnostic performance of contrast enemas is relatively low, making the diagnosis of total colonic aganglionosis challenging. In neonates, ultrasound may be used as an additional imaging modality for the diagnosis of Hirschsprung disease. We describe the unique sonographic findings of total colonic aganglionosis in a term neonate with failure to pass meconium and respiratory distress, who was subsequently diagnosed with Haddad syndrome.

Enhanced enteric neurogenesis by Schwann cell precursors in mouse models of Hirschsprung disease.

Hirschsprung disease (HSCR) is characterized by congenital absence of enteric neurons in distal portions of the gut. Although recent studies identified Schwann cell precursors (SCPs) as a novel cellular source of enteric neurons, it is unknown how SCPs contribute to the disease phenotype of HSCR. Using Schwann cell-specific genetic labeling, we investigated SCP-derived neurogenesis in two mouse models of HSCR; Sox10 haploinsufficient mice exhibiting distal colonic aganglionosis and Ednrb knockout mice showing small intestinal aganglionosis. We also examined Ret dependency in SCP-derived neurogenesis using mice displaying intestinal aganglionosis in which Ret expression was conditionally removed in the Schwann cell lineage. SCP-derived neurons were abundant in the transition zone lying between the ganglionated and aganglionic segments, although SCP-derived neurogenesis was scarce in the aganglionic region. In the transition zone, SCPs mainly gave rise to nitrergic neurons that are rarely observed in the SCP-derived neurons under the normal condition. Enhanced SCP-derived neurogenesis was also detected in the transition zone of mice lacking RET expression in the Schwann cell lineage. Increased SCP-derived neurogenesis in the transition zone suggests that reduction in the vagal neural crest-derived enteric neurons promotes SCP-derived neurogenesis. SCPs may adopt a neuronal subtype by responding to changes in the gut environment. Robust SCP-derived neurogenesis can occur in a Ret-independent manner, which suggests that SCPs are a cellular source to compensate for missing enteric neurons in HSCR.

Autopsy Study of Calretinin Immunohistochemistry in the Anorectal Canal in Young Infants and Potential Implications for Rectal Biopsy Approach in the Neonatal Period.

BACKGROUND: Absent submucosal ganglion cells in biopsies 1-3 cm above the pectinate line establishes the pathologic diagnosis of Hirschsprung Disease (HD). Calretinin stains both ganglion cells and their mucosal neurites and has gained importance in HD diagnosis. Absent calretinin positive mucosal neurites in biopsies at the appropriate level above the pectinate line is highly specific for HD. Whether this applies to lower biopsies is uncertain. To address this, we studied anorectal canal autopsy specimens from infants. METHODS: We performed an autopsy study of infant anorectal canal specimens to describe calretinin staining in this region. Calretinin staining was correlated with histologic and gross landmarks. RESULTS: In all 15 non-HD specimens, calretinin positive mucosal neurites were present in glandular mucosa up to the anorectal line where neurites rapidly diminished. Age range was preterm 26 weeks to 3 months. CONCLUSIONS: Calretinin positive mucosal neurites are present in glandular mucosa up to the anorectal line in young infants. This is potentially important regarding neonatal HD biopsy level and diagnosis. Positive calretinin staining at the anorectal line favors normal innervation making HD unlikely. Absent calretinin positive neurites in glandular mucosa is worrisome for HD in young infants, regardless of location.

Skip segment Hirschsprung's disease: diagnostic clues and surgical management.

It is challenging to establish a definitive diagnosis and initiate timely management for skip segment Hirschsprung's disease (SSHD). Herein, we report three cases of SSHD at our institution between December 2008 and March 2018. Patient #1 was misdiagnosed and underwent three successive operations within 2 years. Patient #2 and #3 were diagnosed timely based on previous experience. A segmental narrowing detected by barium enema may raise the possibility of SSHD. Laparoscopic-guided multipoint biopsy is regarded as a mini-invasive and purposeful way to take representative samples after locating the segmental narrowing intraoperatively and accurate the final diagnosis. The laparoscopic-assisted pull-through procedure with radical resection from the distal rectum to the most proximal margin of the diseased skip segment is safe and effective in treating patients with SSHD.Level of evidence: Level III.

Skip segment Hirschsprung's disease: report of two rare cases and management.

PURPOSE: Skip segment Hirschsprung's disease (SS-HSCR) is defined as the occurrence of a segment of ganglionated intestine surrounded proximally and distally by aganglionosis. The presence of the skip intestinal segment often leads to clinical misdiagnosis, missed diagnosis or inadequate resection of the lesions. The purpose was to describe two new cases of SS-HSCR with the aim of proposing questions regarding the diagnosis and treatment of this rare disease. METHODS: We reported two cases of infants with SS-HSCR that were admitted to our institution within the last 3 years. RESULTS: One patient had a skip segment of ganglionated intestine in the ascending colon. In the other patient, there were no ganglionic cells in the rectum and appendix, but ganglionic cells were visible in the proximal ascending colon. The entire colons in the both cases were finally resected, and a pull-through operation was performed. CONCLUSION: Multipoint biopsy should be performed when the biopsy results are inconsistent with clinical manifestations. Intraoperative laparoscopic identification of the transition zone may be necessary when TCA is suspected. Multisegment biopsy is needed to as a preventative measure for SS-HSCR if TCA is indicated during surgery. Further study is required to determine the optimal length and method of retention of segments.

B-lymphocyte-intrinsic and -extrinsic defects in secretory immunoglobulin A production in the neural crest-conditional deletion of endothelin receptor B model of Hirschsprung-associated enterocolitis.

Hirschsprung disease (HSCR) is a common cause of intestinal obstruction in the newborn. Hirschsprung-associated enterocolitis (HAEC) is a significant and life-threatening complication of HSCR, affecting up to 60% of patients. Animal models of endothelin receptor B (EdnrB) mutation reliably model human HSCR and HAEC. We previously demonstrated intestinal dysbiosis and a gut-specific deficiency of B-lymphocyte-produced secretory IgA (sIgA), the primary effector molecule of mucosal immunity, in mice with homozygous neural crest cell-conditional deletion of EdnrB (EdnrBNCC-/-). To determine mechanisms for sIgA deficiency, we examined intrinsic and extrinsic aspects of B-lymphocyte development and function. Expression of the endothelin axis components [endothelin-1 (ET-1), endothelin-3 (ET-3), endothelin receptor A (EdnrA), EdnrB] were determined over a developmental time course. B-lymphocyte survival and Ig production were assayed in vitro. Polymeric Ig receptor (pIgR)-mediated IgA transport into the intestinal lumen was interrogated. We found endothelin axis component (EdnrA, EdnrB, ET-1, ET-3) expression in developing extramedullary hematopoietic organs and that some splenic B lymphocytes express EdnrB. Splenic B lymphocytes from EdnrBNCC-/- mice showed no intrinsic defect in survival vs. wild-type (WT) B lymphocytes. In vitro stimulation of splenic B lymphocytes demonstrated decreased IgA, IgG, and IgM production in EdnrBNCC-/-vs. WT mice. Additionally, small intestinal pIgR was decreased ∼50% in EdnrBNCC-/- mice. These results suggest an intrinsic B-lymphocyte defect in antibody production as well as an extrinsic defect in IgA transport in the EdnrBNCC-/- model of HAEC. Our results are consistent with human HAEC observations of decreased luminal sIgA and mouse models of other inflammatory bowel diseases, in which decreased pIgR is seen in concert with a dysregulated microbiota. Finally, our results suggest targeting the dysbiotic microbiome and pIgR-mediated sIgA transport as potential therapeutic approaches in prevention and treatment of HAEC.-Medrano, G., Cailleux, F., Guan, P., Kuruvilla, K., Barlow-Anacker, A. J., Gosain, A. B-lymphocyte-intrinsic and -extrinsic defects in secretory immunoglobulinA production in the neural crest-conditional deletion of endothelin receptor B model of Hirschsprung-associated enterocolitis.