ROC-king onwards: intraepithelial lymphocyte counts, distribution & role in coeliac disease mucosal interpretation.

OBJECTIVES: Counting intraepithelial lymphocytes (IEL) is central to the histological diagnosis of coeliac disease (CD), but no definitive 'normal' IEL range has ever been published. In this multicentre study, receiver operating characteristic (ROC) curve analysis was used to determine the optimal cut-off between normal and CD (Marsh III lesion) duodenal mucosa, based on IEL counts on >400 mucosal biopsy specimens. DESIGN: The study was designed at the International Meeting on Digestive Pathology, Bucharest 2015. Investigators from 19 centres, eight countries of three continents, recruited 198 patients with Marsh III histology and 203 controls and used one agreed protocol to count IEL/100 enterocytes in well-oriented duodenal biopsies. Demographic and serological data were also collected. RESULTS: The mean ages of CD and control groups were 45.5 (neonate to 82) and 38.3 (2-88) years. Mean IEL count was 54±18/100 enterocytes in CD and 13±8 in normal controls (p=0.0001). ROC analysis indicated an optimal cut-off point of 25 IEL/100 enterocytes, with 99% sensitivity, 92% specificity and 99.5% area under the curve. Other cut-offs between 20 and 40 IEL were less discriminatory. Additionally, there was a sufficiently high number of biopsies to explore IEL counts across the subclassification of the Marsh III lesion. CONCLUSION: Our ROC curve analyses demonstrate that for Marsh III lesions, a cut-off of 25 IEL/100 enterocytes optimises discrimination between normal control and CD biopsies. No differences in IEL counts were found between Marsh III a, b and c lesions. There was an indication of a continuously graded dose-response by IEL to environmental (gluten) antigenic influence.

Clinical, Endoscopic, and Histologic Characteristics of Ipilimumab-Associated Colitis.

BACKGROUND & AIMS: Ipilimumab, a monoclonal antibody against cytotoxic T-lymphocyte-associated antigen-4, is a treatment for metastatic melanoma that can induce immune-related adverse effects, such as enterocolitis. We aimed to characterize the clinical, endoscopic, and histologic features of ipilimumab-induced colitis and evaluate the efficacy of therapy for this reaction. METHODS: We performed a retrospective analysis of 27 consecutive patients who developed colitis after treatment with ipilimumab infusion therapy for castration-resistant prostate cancer or metastatic melanoma, from April 2007 through September 2012. Clinical, endoscopic, and histologic information was collected from the database of the VU University Medical Center, Amsterdam, The Netherlands. Selected cases were ascertained by cross-checking with endoscopy reports. RESULTS: All patients had diarrhea (range, 3-20 stools per day); 26% had concurrent rectal blood loss and 30% had abdominal pain. These symptoms usually started after 2 infusions of ipilimumab (range, 1-4) and all patients except for 1 (who received no treatment for colitis) were given corticosteroids. Twelve patients had steroid-refractory colitis, for which they received infliximab (5 mg/kg). Diarrhea resolved in all the patients. Colon erythema was detected by endoscopy in 84% of patients, with an absent vascular pattern in all patients. In histologic analyses, colon biopsy specimens ranged from having normal architecture to severe active inflammation. Intraepithelial neutrophilic leucocytes were detected in 72% of samples, cryptitis in 92%, and crypt abscesses in 60%. Crypt irregularities were found in 40% of colon biopsy specimens, indicating chronic disease. CONCLUSIONS: In a retrospective analysis, we associated ipilimumab-associated colitis diarrhea with a variety of endoscopic and histologic features. Treatment with corticosteroids, followed by infliximab in steroid-refractory patients, was successful for all cases.

Single-Cell Analysis of Refractory Celiac Disease Demonstrates Inter- and Intra-Patient Aberrant Cell Heterogeneity.

BACKGROUND & AIMS: Refractory celiac disease type II (RCDII) is a rare indolent lymphoma in the small intestine characterized by a clonally expanded intraepithelial intracellular CD3+surfaceCD3-CD7+CD56- aberrant cell population. However, RCDII pathogenesis is ill-defined. Here, we aimed at single-cell characterization of the innate and adaptive immune system in RCDII. METHODS: Paired small intestinal and blood samples from 12 RCDII patients and 6 healthy controls were assessed by single-cell mass cytometry with a 39-cell surface marker antibody panel, designed to capture heterogeneity of the innate and adaptive immune system. A second single-cell mass cytometry panel that included transcription factors and immune checkpoints was used for analysis of paired samples from 5 RCDII patients. Single-cell RNA sequencing analysis was performed on duodenal samples from 2 RCDII patients. Finally, we developed a 40-marker imaging mass cytometry antibody panel to evaluate cell-cell interactions in duodenal biopsy specimens of RCDII patients. RESULTS: We provide evidence for intertumoral and intratumoral cell heterogeneity within the duodenal and peripheral aberrant cell population present in RCDII. Phenotypic discrepancy was observed between peripheral and duodenal aberrant cells. In addition, we observed that part of the aberrant cell population proliferated and observed co-localization of aberrant cells with CD163+ antigen-presenting cells (APCs) in situ. In addition, we observed phenotypic discrepancy between peripheral and duodenal aberrant cells. CONCLUSIONS: Novel high-dimensional single-cell technologies show substantial intertumoral and intratumoral heterogeneity in the aberrant cell population in RCDII. This may underlie variability in refractory disease status between patients and responsiveness to therapy, pointing to the need for personalized therapy in RCDII based on patient-specific immune profiles.