Introduction

Chronic Intestinal Pseudo-Obstruction (CIPO) is a severe dysmotility disorder, which manifests with recurrent sub-obstructive episodes without mechanical causes of gut occlusion. We previously identified a novel missense mutation (p.Ala622Thr) in RAD21 in a consanguineous family with multiple patients affected by CIPO¹. We now developed a conditional knock-in (Rad21KI^A626T) mouse to express the RAD21 mutation in the enteric nervous system (ENS).

Aims & Methods

We aimed to characterize in vivo and ex vivo the effects of the CIPO-causing RAD21 variant on gut motility, ENS function and structure in a recently generated conditional knock-in mouse. We developed a genetically re-constructed rad21 conditional knock-in (Wnt1-Cre x rad21fl/fl) mouse carrying the p.A626T missense variant (position p.A626 in mouse is homologue of human amino acid p.A622). The mutation p.A626T was introduced in rad21 to be expressed in response to Cre-driven recombination of the floxed alleles, driving its expression into subsets of ENS neurons in response to Wnt1 expression at any developmental points. Homozygous Rad21KI^A626Tvs. wild-type (WT) mice were compared. Intestinal transit time was evaluated with carmine red dye gavage. Recordings of isometric tension using organ-bath techniques was performed to evaluate myogenic and nerve-mediated motility in the large intestine. Immunolabelling was performed in whole-mount myenteric plexus with antibodies against the pan-neuronal marker HuC/D, choline acetyltransferase (ChAT), neuronal nitric oxide synthase (nNOS) and synaptophysin (Syn) in small and large intestine.

Results

We observed an increased intestinal transit time in Rad21KI^A626Tvs. WT (260.50±20.85 min vs. 190.00±12.25 min; P=0.0071). Mean motility index and mean active force, key indexes of myoelectric activity, showed a significant reduction in Rad21KI^A626Tvs. WT mice (3.00±0.23 vs. 5.26±0.58; P<0.005; 0.45±0.05 vs. 0.94±0.10; P=0.0005, respectively). In the small and large intestine of Rad21KI^A626Tmice, HuC/D/ChAT-positive myenteric neurons/field were significantly less vs. WT (18.90 ± 1.40 vs. 32.40 ±2.00; P=0.0152; 19.80±2.10 vs. 32.10±3.80; P=0.0260, respectively). The synaptic vesicle analysis showed a significant decrease of Syn in the Rad21KI^A626T small and large intestine vs. WT (22.12 ± 1.65 vs. 34.11 ± 2.07, P=0.0126 and 22.53 ± 3.31 vs. 36.54 ± 3.54, P=0.0115, respectively).

Conclusion

Rad21KI^A626T mice exhibited a significantly delayed intestinal transit, with reduced motility and a decreased number of ChAT-positive myenteric neurons along with a lower synaptic density. These findings indicate that this conditional k.i. mouse can be considered as a novel model for the study of CIPO.

References

1. Bonora et al., Mutations in RAD21 disrupt regulation of APOB in patients with chronic intestinal pseudo-obstruction. Gastroenterology. 2015;148:771-782.e11.

Introduction

Cholecystectomy is recommended for patients with acute biliary pancreatitis to prevent recurrence and other biliary complications. However, some patients, due to advanced age and comorbidities, are unfit for surgery. The role of endoscopic retrograde cholangiopancreatography (ERCP) with endoscopic sphincterotomy (ES) in these cases is not well established^1,2.

Aims & Methods

We aimed to evaluate whether ES reduces the risk of recurrent biliary pancreatitis (RBP) in patients unfit for cholecystectomy.
A unicentric retrospective review was conducted including all patients admitted for a first episode of acute biliary pancreatitis between January 2016 and November 2023 at a non-tertiary hospital, who were deemed unfit for cholecystectomy by either surgical or anesthetic teams. Patients with concurrent acute cholangitis at admission or during hospitalization, as well as those with prior cholecystectomy or ES, were excluded. Time-to-event analysis was performed using Kaplan-Meier survival curves.

Results

A total of 169 patients were included, with a mean age of 79.07 ± 8.25 years, and 65% were female. The mean Charlson Comorbidity Index was 5.11 ± 2.09. Most cases (94%) presented as mild or moderately severe pancreatitis. The mean follow-up period was 3.80 ± 1.95 years.
During the index admission, 37% (n=62) underwent ERCP with ES.
Recurrent biliary pancreatitis (RBP) occurred in 35 patients (21%), 97% of whom had not undergone ES. Only one patient in the ES group was readmitted for a new episode of pancreatitis (p<0.001, OR 0.035; 95% CI 0.005–0.265). The mean time to recurrence was 2.67 ± 7.78 months. Kaplan-Meier survival analysis demonstrated a significantly lower cumulative incidence of RBP in the ES group (log-rank p<0.001).
Endoscopic sphincterotomy did not significantly reduce other biliary events, including choledocholithiasis, acute cholangitis, and acute cholecystitis (all p>0.05). There was no statistically significant difference in overall mortality between the two groups (p=0.585).

Conclusion

Our findings suggest that ERCP with ES may effectively reduce the recurrence of gallstone pancreatitis in elderly patients with high surgical-anesthetic risk due to comorbidities. Further studies are needed to refine the selection criteria for these patients.

References

1 - Hwang SS, Li BH, Haigh PI. Gallstone pancreatitis without cholecystectomy. JAMA Surg. 2013 Sep;148(9):867-72.
2 - McAlister, V., Davenport, E., & Renouf, E. (2007). Cholecystectomy deferral in patients with endoscopic sphincterotomy. Cochrane Database of Systematic Reviews.

Clinical Case Summary

A 75-year-old woman was admitted to our department for weight loss (25 kg in 10 months) and chronic diarrhea (> 6 months). In history: hypertension in olmesartan 20 mg/day, multinodular goiter. The patient was already tested for anti-transglutaminase antibodies (negative, IgA in normal range) but EGDS showed severe duodenal villous atrophy. On suspicion of ARBsII-associated enteropathy olmesartan was suspended with partial but not complete benefit on clinical. During hospitalization, the patient presented asthenic, occasionally soporific, severely malnourished (Table1) and with a picture of pan-cytopenia (Table1). We excluded neurological (brain CT scan), infectious (blood cultures and co-cultures) and hematologic (bone marrow biopsy) causes. Ultrasound of the intestinal loops and ileo-colonoscopy were normal. Video capsule endoscopy showed marked scalloping of DII and jejunum with extensive ulcers (Figure1). Later, she performed at referral center anterograde double-balloon enteroscopy (DBE). DBE confirmed marked atrophy and map ulcers primarily suggestive of refractory celiac disease type II/EATL with ulcerative jejunum-ileitis. Histologic examination described findings referable to chronic exacerbated, erosive enteritis, not diagnostic for celiac disease. HLA search for celiac disease was negative therefore celiac disease was excluded. Hemotransfusions and nutritional supplementation were administered in consideration of anemia and nutritional deficiency. Empiric/ex-juvantibus therapy with steroid was also set up with marked improvement in symptomatology.
Following hospitalization, she was re-evaluated on an outpatient basis at enteropathy referral center. Here she was first imposed high-dose steroid therapy with marked improvement and weight gain, then Azathioprine in maintenance. She was therefore discharged with a diagnosis of autoimmune enteropathy with likely previous overlap with sartane enteropathy.

References

1. Schiepatti A, et al.. Nomenclature and diagnosis of seronegative coeliac disease and chronic non-coeliac enteropathies in adults: the Paris consensus. Gut. 2022 Nov;71(11):2218-2225. doi: 10.1136/gutjnl-2021-326645. Epub 2022 Jun 8. PMID: 35676085; PMCID: PMC9554081.
2. van Wanrooij RLJ, et al. Adult-Onset Autoimmune Enteropathy in an European Tertiary Referral Center. Clin Transl Gastroenterol. 2021 Aug 1;12(8):e00387. doi: 10.14309/ctg.0000000000000387. PMID: 34333499; PMCID: PMC8323799.
3. Schiepatti A, et al. Systematic review: Clinical phenotypes, histopathological features and prognosis of enteropathy due to angiotensin II receptor blockers. APT. 2024 Feb;59(4):432-444. doi: 10.1111/apt.17855. Epub 2024 Jan 7. PMID: 38185985.