Challenges in IBD Research 2024: Preclinical Human IBD Mechanisms.

Preclinical human inflammatory bowel disease (IBD) mechanisms is one of 5 focus areas of the Challenges in IBD Research 2024 document, which also includes environmental triggers, novel technologies, precision medicine, and pragmatic clinical research. Herein, we provide a comprehensive overview of current gaps in inflammatory bowel diseases research that relate to preclinical research and deliver actionable approaches to address them with a focus on how these gaps can lead to advancements in IBD interception, remission, and restoration. The document is the result of multidisciplinary input from scientists, clinicians, patients, and funders and represents a valuable resource for patient-centric research prioritization. This preclinical human IBD mechanisms section identifies major research gaps whose investigation will elucidate pathways and mechanisms that can be targeted to address unmet medical needs in IBD. Research gaps were identified in the following areas: genetics, risk alleles, and epigenetics; the microbiome; cell states and interactions; barrier function; IBD complications (specifically fibrosis and stricturing); and extraintestinal manifestations. To address these gaps, we share specific opportunities for investigation for basic and translational scientists and identify priority actions.

To address the unmet medical needs of patients with inflammatory bowel diseases (IBD) and move toward cures, preclinical human-relevant research must center on mechanistic questions pertinent to patients with IBD in the 3 areas of disease interception, remission, and restoration.

Fetal lower urinary tract obstruction: proposal for standardized multidisciplinary prenatal management based on disease severity.

OBJECTIVE: To present a single center experience of a standardized prenatal multidisciplinary management protocol for fetal lower urinary tract obstruction (LUTO) and to propose a classification of fetal LUTO based on disease severity. METHODS: This was a retrospective cohort study of 25 consecutive fetal patients with prenatal diagnosis of primary LUTO. Fetal intervention was offered after evaluation by a multidisciplinary team. Analyses were conducted using Bayesian methodology to determine predictors of survival at 6 months postpartum. Odds ratios (ORs) with 95% credibility intervals are reported. RESULTS: Fifteen (60.0%) of the 25 patients referred for assessment survived to postnatal evaluation. Fetal vesicoamniotic shunt was placed in 14 (56.0%) patients with 12 survivors. Multivariable analysis suggested that fetal intervention (OR, 6.97 (0.88-70.16), Pr(OR > 1) = 96.7%), anhydramnios (OR, 0.12 (0.04-0.35), Pr(OR < 1) = 99.9%), favorable fetal urine analysis (OR, 3.98 (0.63-25.15), Pr(OR > 1) = 92.7%) and absence of renal cortical cysts (OR, 3.9 (0.66-24.2), Pr(OR > 1) = 93.3%) were predictors of survival. CONCLUSIONS: Fetal intervention and fetal renal function were independently associated with postnatal survival of fetuses with LUTO. A classification based on the severity of disease is proposed. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Quantification of liver herniation in fetuses with isolated congenital diaphragmatic hernia using two-dimensional ultrasonography.

OBJECTIVES: To describe a method of quantifying the amount of liver herniation in fetuses with isolated congenital diaphragmatic hernia (CDH) using two-dimensional ultrasonography and to correlate this finding with neonatal outcome. METHODS: Ultrasound images obtained from 77 consecutive fetuses that presented with isolated CDH between January 2004 and July 2012 were reviewed. Liver herniation and thoracic area were measured in a cross-sectional plane of the fetal chest at the level of the four-chamber view of the heart (the same section as is used to measure the lung area-to-head circumference ratio) and the ultrasound-derived liver-to-thoracic area ratio (US-LiTR) was calculated by dividing the liver herniation area by the thoracic area. Receiver-operating characteristics (ROC) curve analysis was used to evaluate the performance of US-LiTR in predicting neonatal outcome (survival to 6 months after delivery and need for extracorporeal membrane oxygenation (ECMO)). In addition, the US-LiTR was compared with the magnetic resonance imaging (MRI)-derived volume ratio (MRI-LiTR) and percentage of liver herniation (MRI-%LH). RESULTS: The overall neonatal mortality in the 77 cases with isolated CDH was 20.8% (16/77). ECMO was needed in 35.5% (27/76) of the newborns, with a survival rate of 52%. The US-LiTR was associated statistically with mortality (P < 0.01) and with the need for ECMO (P < 0.01). Good correlations were observed between US-LiTR and MRI-LiTR (r = 0.87; P < 0.001) and between US-LiTR and MRI-%LH (r = 0.90; P < 0.001). Based on ROC curve analysis, all three parameters had similar accuracy in predicting mortality (US-LiTR: area under the ROC curve (AUC), 0.78 (95% CI, 0.65-0.92), P < 0.01; MRI-LiTR: AUC, 0.77 (95% CI, 0.63-0.90), P < 0.01; MRI-%LH: AUC, 0.79 (95% CI, 0.65-0.92), P < 0.01, respectively) as well as the need for ECMO (US-LiTR: AUC, 0.72 (95% CI, 0.60-0.84), P < 0.01; MRI-LiTR: AUC, 0.73 (95% CI, 0.60-0.88), P < 0.01; MRI-%LH: AUC, 0.77 (95% CI, 0.64-0.89), P < 0.01, respectively). CONCLUSIONS: Two-dimensional ultrasound measurement of the amount of liver herniation in fetuses with isolated CDH is feasible and demonstrates a predictive accuracy for neonatal outcome similar to that of MRI.

Congenital heart anomaly in newborns with congenital diaphragmatic hernia: a single-center experience.

OBJECTIVE: To evaluate the impact of the presence of a congenital heart anomaly (CHA) and its potential contribution to morbidity and mortality in infants with congenital diaphragmatic hernia (CDH). METHODS: In this retrospective cohort study, prenatal and postnatal data of all newborns diagnosed with CDH between January 2004 and December 2012 in a single center were reviewed. Cases were classified into two groups: those with 'isolated' CDH and those with both CDH and CHA. Patients with CHA were further subclassified into those with a major or minor CHA based on the Risk Adjustment for Congenital Heart Surgery-1 (RACHS-1), and the Society of Thoracic Surgeons-European Association for Cardiothoracic Surgery (STS-EACTS) scoring systems. Patients with associated non-cardiac anomalies, including 'syndromic cases', were excluded from the analysis. Primary and secondary outcomes were survival up to 1 year of age and a need for extracorporeal membrane oxygenation (ECMO), respectively. RESULTS: Of the 180 infants with CDH, 41 were excluded because of the presence of non-cardiac associated anomalies, 118 had isolated CDH and 21 had CDH with CHA (16 with minor and five with major CHA). Receiver-operating characteristics curve analysis demonstrated that the best cut-off for survival was when the score for CHA was ≤ 2 for both RACHS-1 (area under the curve (AUC), 0.74 (P = 0.04); sensitivity, 80.0%; specificity, 87.5%) and STS-EACTS (AUC, 0.83 (P = 0.03); sensitivity, 100%; specificity, 87.5%). Survival rate at 1 year was significantly lower in those with CHD and a major CHA (40.0%; P = 0.04) than in those with isolated CDH (77.1%) and those with CDH and a minor CHA (81.3%). We found no significant differences among the groups with regard to the need for ECMO. CONCLUSIONS: In general, a milder form of CHA does not appear to have a negative impact on the survival of infants with CDH. However, mortality appears to be significantly higher in infants with CDH and a major form of CHA. The scoring systems appear to be useful as predictors for classifying the effects of CHA in this population of patients.

CB1 cannabinoid receptor stimulation during adolescence impairs the maturation of GABA function in the adult rat prefrontal cortex.

Converging epidemiological studies indicate that cannabis abuse during adolescence increases the risk of developing psychosis and prefrontal cortex (PFC)-dependent cognitive impairments later in life. However, the mechanisms underlying the adolescent susceptibility to chronic cannabis exposure are poorly understood. Given that the psychoactive constituent of cannabis binds to the CB1 cannabinoid receptor, the present study was designed to determine the impact of a CB1 receptor agonist (WIN) during specific windows of adolescence on the functional maturation of the rat PFC. By means of local field potential recordings and ventral hippocampal stimulation in vivo, we found that a history of WIN exposure during early (postnatal days - P35-40) or mid-(P40-45) adolescence, but not in late adolescence (P50-55) or adulthood (P75-80), is sufficient to yield a state of frequency-dependent prefrontal disinhibition in adulthood comparable to that seen in the juvenile PFC. Remarkably, this prefrontal disinhibition could be normalized following a single acute local infusion of the GABA-Aα1 positive allosteric modulator Indiplon, suggesting that adolescent exposure to WIN causes a functional downregulation of GABAergic transmission in the PFC. Accordingly, in vitro recordings from adult rats exposed to WIN during adolescence demonstrate that local prefrontal GABAergic transmission onto layer V pyramidal neurons is markedly reduced to the level seen in the P30-35 PFC. Together, these results indicate that early and mid-adolescence constitute a critical period during which repeated CB1 receptor stimulation is sufficient to elicit an enduring state of PFC network disinhibition resulting from a developmental impairment of local prefrontal GABAergic transmission.

Fetal lung volume and quantification of liver herniation by magnetic resonance imaging in isolated congenital diaphragmatic hernia.

OBJECTIVE: To determine associations between fetal lung and liver herniation volumes measured by magnetic resonance imaging (MRI) and mortality/need for extracorporeal membrane oxygenation (ECMO) in cases of isolated congenital diaphragmatic hernia (CDH). A secondary objective was to compare prenatal MRI parameters with two-dimensional ultrasound lung measurements. METHODS: A retrospective review of medical records of all fetuses with isolated CDH evaluated between January 2004 and July 2012 was performed. The following MRI parameters were measured at 20-32 weeks: observed/expected total fetal lung volume (o/e-TLV), predicted pulmonary volume (PPV), percentage of liver herniated into the fetal thorax (%LH) and the liver/thoracic volume ratio (LiTR). These were compared with the ultrasound-determined lung-to-head ratio (LHR) and the observed/expected LHR (o/e-LHR) in the same cohort. The predictive value of MRI and ultrasound parameters for mortality and the need for ECMO was evaluated by univariate, multivariate and factor analysis and by receiver-operating characteristics curves. RESULTS: Eighty fetuses with isolated CDH were evaluated. Overall mortality was 18/80 (22.5%). Two newborns died a few hours after birth. ECMO was performed in 29/78 (37.2%) newborns, with a survival rate of 48.3% (14/29). The side of the diaphragmatic defect was not associated with mortality (P = 0.99) or the need for ECMO (P = 0.48). Good correlation was observed among o/e-TLV, PPV, LHR and o/e-LHR as well as between %LH and LiTR (r = 0.89; P < 0.01); however, fetal lung measurements and measures of liver herniation were not correlated (all P > 0.05). All parameters were statistically associated with mortality or the need for ECMO. The best combination of measurements to predict mortality was o/e-TLV and %LH, with 83% accuracy. CONCLUSION: Mortality and the need for ECMO in neonates with isolated CDH can be best predicted using a combination of MRI o/e-TLV and %LH.

Perinatal outcome after fetoscopic release of amniotic bands: a single-center experience and review of the literature.

OBJECTIVES: To present two successful cases of fetoscopic release of amniotic bands with umbilical cord involvement and provide a review of the literature on fetal intervention for amniotic band syndrome (ABS). METHODS: Two cases of ABS were considered in conjunction with a review of the literature. A total of 14 fetuses with ABS underwent fetoscopic intervention between 1965 and 2012. Two of the authors independently completed literature searches in PubMed, Ovid and MEDLINE for articles related to ABS. RESULTS: Among 14 cases of ABS (12 published and our own two), 57% and 7% were complicated by preterm premature rupture of membranes and spontaneous preterm birth, respectively. Overall, fetoscopic intervention preserved limb function in 50% (7/14) of cases. Three cases involved intraoperative complications including intra-amniotic bleeding and uterine wall bleeding, and incomplete procedure due to ineffective equipment. CONCLUSION: Fetoscopic release of amniotic bands with minimally invasive surgery may allow preservation of life and/or limb function in cases of ABS. The acceptable functional outcome in 50% of cases is reassuring, although more experience and further studies are needed to determine the selection criteria that will justify the risk of this invasive in-utero therapy for ABS.

Laparoscopy-assisted fetoscopy for laser surgery in twin-twin transfusion syndrome with anterior placentation.

OBJECTIVE: To compare a laparoscopy-assisted fetoscopic approach with an ultrasound-directed percutaneous approach for laser photocoagulation of placental anastomoses in cases of twin-twin transfusion syndrome (TTTS) with anterior placentation. METHOD: We performed a retrospective review of all cases that underwent laser ablation of placental anastomoses for TTTS with an anterior placenta at Texas Children's Fetal Center from November 2006 to November 2008. The two cohorts were identified by chart review based on the type of approach: laparoscopy-assisted vs. ultrasound-guided percutaneous uterine entry for fetoscopy. Operative and outcome data were extracted and the groups were compared using statistical methods, taking P < 0.05 as statistically significant. RESULTS: In the 100 cases of TTTS studied, 48 had an anterior placenta. Fifteen (31%) of these underwent laparoscopy-assisted fetoscopy (LAF) while a percutaneous approach was used in the remaining 33 (69%) cases. The total procedure time was longer in the LAF group than in the percutaneous group (96.1 +/- 25 vs. 67.9 +/- 28 min; P < 0.01). There was no difference in the rate of preterm premature rupture of membranes up to 2 weeks and 4 weeks after surgery (7 vs. 15% and 13 vs. 21%, for the LAF group vs. the percutaneous group, respectively; P = 0.7). The gestational ages at delivery were similar: 30.3 +/- 4.5 weeks in the LAF group and 29.2 +/- 4.6 weeks in the percutaneous group (P = 0.32). The overall survival rate at birth was tending towards better survival in the laparoscopic group than in the percutaneous group (80 vs. 61%, respectively; P = 0.06). The neonatal survival rate was better with the LAF approach than with the percutaneous approach (80 vs. 59%, respectively; P = 0.045). CONCLUSION: Laparoscopy-assisted entry of the uterus is associated with improved neonatal survival for laser photocoagulation in cases of TTTS with a complete anterior placentation.

Management of urethrocutaneous fistula following hypospadias repair.

Urethrocutaneous fistulas complicating hypospadias repair appear a common problem. There appears less data in the literature regarding the risk and management of recurrent fistulas. A retrospective review of urethrocutaneous fistulas complicating hypospadias repair was performed to evaluate their aetiology, management and outcome. Between 1993 and 2003, 1,753 patients had a hypospadias repair at our institution. Overall 123 (7%) boys developed a fistula, although detailed information was available on 117 patients only. Median age was 3.5 years at the time of fistula repair; 13% had anterior, 57% had middle and 30% had posterior hypospadias. The most common primary surgical procedure was a Durham Smith two-stage repair in 29% (n = 34), followed by a Tubularised Incised Plate urethroplasty in 19% (n = 22) and an Onlay in 14% (n = 16). Thirty-one (27%) patients developed a recurrent fistula, 9 (29%) of which recurred following a second repair. None recurred after a third repair. The risk of a recurrent fistula after an initial distal fistula repair was 12.5% and after a posterior fistula was 62% (chi(2) = 15.4, P = 0.001). Use of a stent, suture type, numbers of fistula and closure attempts did not influence the recurrence rate. Undiagnosed distal obstruction was thought to be related to 27 of 117 first fistula repairs (23%) and 4 of 31 second fistula repairs (13%). The risk of recurrent urethrocutaneous fistula was increased in those boys with a posterior fistula, following a simple repair or when there was evidence of distal urethral obstruction.

Evaluation of the NK2 homeobox 1 gene (NKX2-1) as a Hirschsprung's disease locus.

Hirschsprung's disease (HSCR, colonic aganglionosis) is an oligogenic entity that usually requires mutations in RET and other interacting loci. Decreased levels of RET expression may lead to the manifestation of HSCR. We previously showed that RET transcription was decreased due to alteration of the NKX2-1 binding site by two HSCR-associated RET promoter single nucleotide polymorphisms (SNPs). This prompted us to investigate whether DNA alterations in NKX2-1 could play a role in HSCR by affecting the RET-regulatory properties of the NKX2-1 protein. Our initial study on 86 Chinese HSCR patients revealed a Gly322Ser amino acid substitution in the NKX2-1 protein. In this study, we have examined 102 additional Chinese and 70 Caucasian patients and 194 Chinese and 60 Caucasian unselected, unrelated, subjects as controls. The relevance of the DNA changes detected in NKX2-1 by direct sequencing were evaluated using bioinformatics, reporter and binding-assays, mouse neurosphere culture, immunohistochemistry and immunofluorescence techniques. Met3Leu and Pro48Pro were identified in 2 Caucasian and 1 Chinese patients respectively. In vitro analysis showed that Met3Leu reduced the activity of the RET promoter by 100% in the presence of the wild-type or HSCR-associated RET promoter SNP alleles. The apparent binding affinity of the NKX2-1 mutated protein was not decreased. The Met3Leu mutation may affect the interaction of NKX2-1 with its protein partners. The absence of NKX2-1 expression in mouse but not in human gut suggests that the role of NKX2-1 in gut development differs between the two species. NKX2-1 mutations could contribute to HSCR by affecting RET expression through defective interactions with other transcription factors.

An example of psychological adjustment in chronic illness: Hirschsprung's disease.

The aim of this study was to investigate the outcomes after definitive surgical correction for children with Hirschsprung's disease (HD) and the psychosocial impact of HD on the child and family. The total sample comprised 72 children with HD along with their families. The development of a condition-specific questionnaire measured the functional and psychosocial outcomes for children with HD with parental perception of their child's condition. Psychiatric measures were also examined to assess psychiatric morbidity. The greatest functional problem after definitive surgery for HD was faecal soiling (76%). The principle findings of the study were that (1) HD did not have a significant impact on the child's rate of psychiatric morbidity and levels of hopefulness in comparison to the normal population, (2) surgical and psychosocial functioning improved with increasing age and, (3) families remain troubled about their future with HD and dealing with psychosocial difficulties related to the condition (such as distress because of faecal soiling). Specifically, faecal soiling was found to be physically, emotionally and psychosocially distressing complication. Bowel functioning and psychosocial distress improves with increasing age and parental and medical professional support. Despite the significant impairment of faecal continence, we found that children/young adults with HD have minimal psychiatric morbidity, yet experience condition-specific psychosocial problems (e.g. embarrassment and distress/discomfort). HD does not increase the rate of clinical psychiatric morbidity in children and families with HD, but does determine the context of their daily distress and concern.

Diagnostic accuracy of surgeon-performed focused abdominal sonography (FAST) in blunt paediatric trauma.

AIM: To study the diagnostic accuracy and clinical efficacy of surgeon-performed focused abdominal sonography (FAST) in paediatric blunt abdominal trauma (BAT). MATERIALS AND METHOD: This was a prospective, single blinded study conducted at The Children's Hospital at Westmead Sydney (CHW). All patients with BAT that justified a trauma call activated on presentation to the Emergency Department (ED) had a FAST performed by the Trauma Fellow. The attending surgical team was blinded to the result of the FAST. An independent radiologist reviewed the FAST pictures, and the findings were compared with computerised tomography (CT), ultrasound (US), laparotomy and the clinical outcome of the patient. Sensitivity, specificity and predictive values were calculated. RESULTS: A total of 85 patients (39 M; 26 F) were enrolled in the study between February 2002 and January 2003. The age ranged between 4 months and 16 years. The mean Injury Severity Score (ISS) was 6 (range 1-38). FAST was performed in a mean time of 3 min. Inter-rater agreement was 96%. FAST was positive in nine as confirmed by a CT scan of the abdomen. Three patients underwent laparotomy, two for bowel injuries and one for a Grade III liver laceration. Of the remaining 76, 19 had a CT, which showed evidence of intra-abdominal injury in seven patients. There were two false negative studies resulting in a sensitivity of 81%, specificity of 100%, negative predictive value of 97%, positive predictive value of 100% and an accuracy of 97%. CONCLUSIONS: Surgeon-performed FAST for BAT was safe and accurate with a high specificity. It would seem a potentially valuable tool in the evaluation of paediatric blunt trauma victims for free fluid within the peritoneal cavity.

Blunt traumatic diaphragmatic injuries in children.

Diaphragmatic injuries following blunt trauma are rare. From January 1988 to February 2002 eight children were treated at the Children's Hospital at Westmead for diaphragmatic injury. Male to female ration was 5:3. Motor vehicle crashes were the most common cause. The injury was left-sided in four, right sided in three and central in one. Initial plain radiograph and computerised tomography detected the injury in 50% of cases. Laparotomy, contrast study and autopsy identified the rupture in one each. Associated injuries were present in all cases. Seven children had laparotomy and repair of the diaphragmatic rupture. The commonest site of rupture was posterolateral (37.5%). Diagnosis was delayed in two cases. There were two deaths (25% mortality) in the series, both due to associated injuries. Although rare, diaphragmatic rupture must be considered in any child with thoracoabdominal injury. Diagnosis may be difficult and require extensive investigation. Mortality usually results from associated injuries.

Mortality due to constipation and short-segment Hirschsprung's disease.

We report a case of mortality secondary to constipation. A 12-year-old child with a history of constipation from the age of 9 years presented in moribund condition with intestinal obstruction secondary to idiopathic constipation. He underwent laparotomy and died within 24 h of operation. At postmortem there was no evidence of abnormalities of the enteric nervous system. A 2nd case of early neonatal death from Hirschsprung's disease is presented to demonstrate that short-segment aganglionosis can be detected at postmortem. Enterocolitis can rapidly progress and be fatal in short-segment Hirschsprung's disease.

MNGIE with lack of skeletal muscle involvement and a novel TP splice site mutation.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive multisystem disorder caused by thymidine phosphorylase (TP) deficiency, resulting in severe gastrointestinal dysmotility and skeletal muscle abnormalities. A patient is reported with a classical MNGIE clinical presentation but without skeletal muscle involvement at morphological, enzymatic, or mitochondrial DNA level, though gastrointestinal myopathy was present. MNGIE was diagnosed by markedly raised plasma thymidine and reduced thymidine phosphorylase activity. Molecular genetic analysis showed a homozygous novel splice site mutation in TP. On immunohistochemical studies there was marked TP expression in the CNS, in contrast to what has been observed in rodents. It is important to examine the most significantly affected tissue and to measure TP activity and plasma thymidine in order to arrive at an accurate diagnosis in this condition.