Damianos, John A

ABSTRACT Background Chimeric antigen receptor T‐cell (CAR‐T) therapy has revolutionised the treatment of hematologic malignancies, and its use is expanding rapidly into numerous other disease states including autoimmune diseases. However, CAR‐T therapy is associated with a spectrum of immune‐related toxicities. In addition to the already well characterized cytokine release syndrome and immune effector cell‐associated neurotoxicity syndrome, it has become apparent that rarely, CAR‐T can cause gastrointestinal mucosal inflammation, termed immune effector cell‐mediated enterocolitis (IEC‐EC). Aims This state‐of‐the‐art review highlights the CAR‐T mechanism and details the epidemiology, pathophysiology, clinical manifestations, endoscopic and histopathologic features, and management of IEC‐EC. Methods This review presents the current state of knowledge through a comperhensive and detailed synthesis of all case series reported in the literature to date. Results Occurring in up to approximately 6% of patients typically following B cell maturation antigen‐targeted CAR‐T therapy, IEC‐EC presents with severe diarrhoea and malabsorption, responds poorly to treatment, and portends a dire prognosis. Multi‐disciplinary management should centre on early diagnosis, supportive cares, assessment and treatment of infections, and step‐up pharmacotherapy, often featuring biologics and small molecules drawn from the inflammatory bowel disease pharmacologic armamentarium. Conclusions Clinicians should maintain a high degree of vigilance for IEC‐EC in patients presenting with gastrointestinal symptoms following CAR‐T treatment. Early recognition and multi‐disciplinary treatment may improve patient outcomes.

ABSTRACT Background Bile acid (BA) malabsorption (BAM) is a common cause of chronic diarrhoea and may occur in some patients due to abnormalities of the gut microbiota. Effects of probiotics on faecal secretory BAs, particularly the primary BA, chenodeoxycholic acid, are unclear. Aim/Methods We conducted a randomized, double‐blind, placebo‐controlled trial of the De Simone formulation 8‐strain probiotic in 24 patients previously diagnosed with BAM. Patients were randomized to 3 weeks of the probiotic (900 billion bacteria) or placebo (maltose), both administered three times daily. Symptoms, serum 7 α C4, faecal primary BAs, intestinal permeability by 13 C‐mannitol‐lactulose test (0.1 and 1 g of the sugars respectively) over 24 h, faecal short chain fatty acids (SCFA), microbiome, and metabolome were assessed at baseline and post‐intervention. Results Data from 22 patients were included. Probiotic supplementation was associated with a significant decrease in % faecal primary BAs (chenodeoxycholic acid and cholic acid) with median change from baseline −5.7 [IQR −10.3, 0.9]% compared to 9.8 [IQR 0.2, 20.6]% on placebo ( p = 0.012). The faecal microbiome was significantly different in the probiotic group after intervention, driven by probiotic‐specific species. There were no significant differences in symptoms, intestinal permeability, or SCFA. However, there was a numerical difference in the changes from baseline in 0‐2 h 13 C‐mannitol excretion −1.9 [−13.9, 4.2] mg for the probiotic and 1.0 (−0.5, 12.7) mg for placebo ( p = 0.084). Conclusions The De Simone formulation probiotic induced significant microbiome and metabolome changes in patients with BAM, ultimately leading to a decrease in % faecal primary BAs and possible reduction in intestinal permeability. Clinical Trials.gov registration NCT #06609148, January 2, 2025.

INTRODUCTION: To perform a proof-of-concept study to evaluate the performance of individual and combined anorectal manometry and balloon expulsion testing (BET) parameters for diagnosing dyssynergic defecation (DD) using machine learning (ML). METHODS: A single gastrointestinal motility specialist assessed (2008–2018) 307 patients. A ML model was constructed on anorectal manometry/BET data. BET was weight-based in 235 patients and time-based in 72 patients. Missing data were imputed. Data were split 75% train/25% test with preprocessing performed. Five common ML models were trained, and performance was compared using receiver operating characteristic (ROC) area under the curve and accuracy based on 100 bootstrapped samples. The most accurate models were fine-tuned and evaluated on the test set. RESULTS: The median age was 40 years, body mass index 22.2 kg/m 2 , and 81% were women. Two-hundred and 22 (72.3%) patients had a clinical diagnosis of DD. Compared with patients without clinical diagnosis of DD, patients with DD had significantly lower rectoanal pressure gradient (RAG) (median −34.7 [IQR −57.1, −13.0] vs −24.6 [IQR −44.5, −2.4] mm Hg, P = 0.009) and more abnormal BET (59.5% vs 11.8%, P < 0.001). Four features were retained in the optimized model as predictors of DD: abnormal BET, greater resting anal pressure (RAP), and more negative RAG. The optimal parameter was abnormal BET ( P = 0.003), but combinations of 2 manometry results (RAP and RAG) yielded positive predictive values (PPVs) >80%. The optimized logistic regression model had an area under the curve of 0.878, with a sensitivity of 75.0% and specificity of 81.8% at a probability threshold of 0.704. DISCUSSION: Abnormal BET, or a combination of 2 manometric parameters (RAP and RAG), provides >80% positive predictive value for diagnosing DD in patients with chronic constipation.

Background: Mastocytic enterocolitis has been proposed as a cause of chronic diarrhea and abdominal pain, characterized by increased mast cells in gastrointestinal mucosal biopsies. However, its clinical significance remains uncertain. Methods: We present a case report of a patient identified to have high levels of mast cells on gastrointestinal biopsies. We then reviewed cases at Mayo Clinic where patients had >20 mast cells per high-power field (HPF) on gastrointestinal biopsies. Patients with alternative explanations for mast cell elevation, including systemic mastocytosis were excluded. We analyzed demographics, clinical presentations, pathology reports, serum and urine mast cell mediators, inflammatory markers, bone marrow biopsies, motility testing, and treatment responses. Results: We identified 42 patients (30 female and 12 male) with elevated mast cells on biopsy (mean age: 41 y, range: 17 to 81). Mast cells were quantified using KIT (CD117) staining, with no abnormal clumping or morphology, and CD25 immunostaining was negative in all cases. Eosinophilic infiltration was absent in all but one case. Small intestinal bacterial overgrowth (SIBO) was found in 78% of patients tested. Treatments varied widely, with antihistamines and cromolyn being the most common. Among 21 patients with sufficient follow-up, only 5 (24%) reported partial or complete symptom improvement, while 76% experienced persistent symptoms. Conclusion: Routine assessment of mast cells on gastrointestinal biopsies is not supported by our findings. Elevated mucosal mast cells, in the absence of systemic mast cell disorders, may not indicate a distinct disease entity. Evaluation should focus on ruling out other inflammatory, allergic, infectious, and motility disorders, as well as SIBO. Further research is needed to determine the clinical significance of increased mucosal mast cells and their role in gastrointestinal symptomatology.

ABSTRACT Background Microbial overgrowth (MO) in the small intestine can cause gastrointestinal symptoms and may arise from stasis, such as dysmotility. Microtypes of MO include small intestinal bacterial overgrowth (SIBO) and intestinal methanogen overgrowth (IMO). Dyssynergic defecation (DD) is associated with constipation and slow colonic transit (STC). Our aim was to assess the relationship between DD and MO. Methods We retrospectively identified patients who underwent both anorectal manometry (ARM) and balloon expulsion testing (BET) for DD, and MO testing using either small intestinal aspirate culture or breath testing. SIBO was analyzed using two culture thresholds: ≥ 10 5 CFU/mL and ≥ 10 3 CFU/mL. Chi‐square tests compared positive vs. negative results. Key Results 436 patients underwent culture of SB aspirates. At the ≥ 10 5 CFU/mL threshold, 41.7% were diagnosed with SIBO, and 87.4% at ≥ 10 3 CFU/mL. At ≥ 10 5 CFU/mL, percent anal relaxation was significantly lower in SIBO‐positive patients. SIBO patients were more likely to have reduced anal relaxation ( p = 0.032), but no other ARM parameters or BET > 60 s. At ≥ 10 3 CFU/mL, a more negative recto‐anal pressure differential (RAPD) was observed, along with a combination of RAPD < −45 mmHg and resting anal pressure > 90 mmHg. 637 patients underwent breath testing for MO, with 174 positive results, predominantly showing IMO (73%). In this group, BET was significantly longer, and anal relaxation was significantly lower. SIBO at ≥ 10 3 CFU/mL was more prevalent in DD than STC (85.5% vs. 64.7%, p = 0.002). IMO was more common in DD than STC ( p = 0.021). Conclusion/Inferences DD may be a risk factor for MO, often with evidence of methanogenesis.

ABSTRACTIntroductionUpper and lower gastrointestinal (GI) dysfunctions frequently coexist, potentially mediated by gastrocolonic or cologastric neural reflexes. This study aims to assess the prevalence of impaired gastric accommodation (GA) and delayed gastric emptying (GE) among patients with slow colonic transit (CT), dyssynergic defecation (DD), and to evaluate relationships between CT or DD with impaired GA and delayed GE.MethodsWe reviewed records of 178 adult patients at Mayo Clinic (2005–2025) with documented slow CT or DD (respectively based on scintigraphy and high‐resolution anorectal manometry [ARM] and balloon expulsion [BE]) who underwent 99mTc‐SPECT measurement of GA and scintigraphic GE of 320‐kcal, 30% fat egg meal. Slow CT was defined by geometric center (GC) at 48 h < 2.1 for males and < 1.9 for females. Abnormal GA ratio was assessed as reduced < 2.62 or increased > 3.85, and delayed GE % < 75% at 4 h. Correlations were assessed using Spearman rank test.ResultsReduced GA was found in 23.7% with DD and 26.7% with slow CT, while increased GA was observed in 30.1% and 24.4%, respectively. Delayed GE was present in 20.5% DD patients and 35.6% slow CT patients. GC 48 h and 24 h were positively correlated with GE% 4 h (Rs = 0.279, and Rs = 0.294 respectively, both p < 0.001) suggesting slow CT retards GE. GC 48 h was moderately correlated with resting anal pressure (Rs = 0.259, p < 0.001) and negatively with the rectoanal pressure gradient (Rs = −0.166, p = 0.027). No significant correlations were observed between CT and GA.ConclusionSlow CT is associated with slower GE, suggesting cologastric reflex inhibition, but not with GA. There is a high prevalence of impaired GA and delayed GE in slow CT and DD.

Coeliac disease is characterised by immune-mediated damage to the small intestine in response to dietary gluten in genetically predisposed individuals. Increased intestinal permeability is a central component to its pathophysiology. This review explores the evidence for increased permeability in coeliac disease and the underlying mechanisms, including the roles of zonulin, inflammatory cytokines, microbial alterations and immune responses to gliadin peptides. We also review comprehensively the therapies targeting barrier integrity and normalising intestinal permeability, including particular diets and supplements, and experimental and improved medications including larazotide acetate and IMU-856. Finally, we highlight the need for reliable biomarkers for evaluating increased permeability in coeliac disease and advocate for further research on therapies which normalise barrier function, particularly as a strategy to maintain remission.

ABSTRACT Background Several genetic syndromes that affect nerve development and functioning may involve the enteric nervous system and present clinically as dysmotility syndromes, typically in childhood. Aim To review the enteric neuromuscular manifestations, predominantly observed in adults, of neurofibromatosis type I at a tertiary referral center. Methods We conducted a medical records review at the Mayo Clinic and documented clinical manifestations and findings on radiology, pathology, and specialized motility tests of the esophagus, stomach, colon, and rectal evacuatory functions. The tests included scintigraphic gastrointestinal and colonic transit measurements, intraluminal esophageal, gastrointestinal, colonic, and anorectal manometry, and balloon expulsion test. Results Among 2406 with documented NF1, the gastrointestinal manifestations were obstruction or dysmotility, seen in 2% of the cohort. Thirteen patients had small bowel or colonic obstructions: 4 gastrointestinal stromal tumors, 3 malignant peripheral nerve sheath tumors, 3 neurofibromas, 1 diffuse ganglioneuromatosis, 1 schwannoma, and 1 inflammatory fibroid polyp. In addition, 38 patients had abnormal gut motility, including esophageal achalasia or spasm, delayed gastric emptying, slow colonic transit, and dyssynergic defecation. Gastric, small bowel, and colonic manometry were characterized by normal amplitude incoordinated contractions suggestive of neuropathy. In the few resected specimens, myenteric plexus proliferation or diffuse ganglioneuromatosis was identified histologically. Conclusions In addition to mechanical obstruction, typically due to benign tumors affecting smooth muscle or components of nerve (sheath or nerve fiber), patients with NF1 may present with dysmotility syndromes such as gastroparesis, slow colonic transit, or global dysmotility. Neuropathic dysmotility in NF1 can be identified by manometry and by histological evidence of myenteric plexus proliferation or diffuse ganglioneuromatosis.