Epigenetic Reprogramming of Autophagy Drives Mutant IDH1 Glioma Progression and Response to Radiation.

Mutant isocitrate dehydrogenase 1 (mIDH1; IDH1 R132H ) exhibits a gain of function mutation enabling 2-hydroxyglutarate (2HG) production. 2HG inhibits DNA and histone demethylases, inducing epigenetic reprogramming and corresponding changes to the transcriptome. We previously demonstrated 2HG-mediated epigenetic reprogramming enhances DNA-damage response and confers radioresistance in mIDH1 gliomas harboring p53 and ATRX loss of function mutations. In this study, RNA-seq and ChIP-seq data revealed human and mouse mIDH1 glioma neurospheres have downregulated gene ontologies related to mitochondrial metabolism and upregulated autophagy. Further analysis revealed that the decreased mitochondrial metabolism was paralleled by a decrease in glycolysis, rendering autophagy as a source of energy in mIDH1 glioma cells. Analysis of autophagy pathways showed that mIDH1 glioma cells exhibited increased expression of pULK1-S555 and enhanced LC3 I/II conversion, indicating augmented autophagy activity. This dependence is reflected by increased sensitivity of mIDH1 glioma cells to autophagy inhibition. Blocking autophagy selectively impairs the growth of cultured mIDH1 glioma cells but not wild-type IDH1 (wtIDH1) glioma cells. Targeting autophagy by systemic administration of synthetic protein nanoparticles packaged with siRNA targeting Atg7 (SPNP-siRNA-Atg7) sensitized mIDH1 glioma cells to radiation-induced cell death, resulting in tumor regression, long-term survival, and immunological memory, when used in combination with IR. Our results indicate autophagy as a critical pathway for survival and maintenance of mIDH1 glioma cells, a strategy that has significant potential for future clinical translation. One Sentence Summary: The inhibition of autophagy sensitizes mIDH1 glioma cells to radiation, thus creating a promising therapeutic strategy for mIDH1 glioma patients. Graphical abstract: Our genetically engineered mIDH1 mouse glioma model harbors IDH1 R132H in the context of ATRX and TP53 knockdown. The production of 2-HG elicited an epigenetic reprogramming associated with a disruption in mitochondrial activity and an enhancement of autophagy in mIDH1 glioma cells. Autophagy is a mechanism involved in cell homeostasis related with cell survival under energetic stress and DNA damage protection. Autophagy has been associated with radio resistance. The inhibition of autophagy thus radio sensitizes mIDH1 glioma cells and enhances survival of mIDH1 glioma-bearing mice, representing a novel therapeutic target for this glioma subtype with potential applicability in combined clinical strategies.

Detection of Barrett's neoplasia with a near-infrared fluorescent heterodimeric peptide.

BACKGROUND: Esophageal adenocarcinoma (EAC) is a molecularly heterogeneous disease with poor prognosis that is rising rapidly in incidence. We aimed to demonstrate specific binding by a peptide heterodimer to Barrett's neoplasia in human subjects. METHODS: Peptide monomers specific for EGFR and ErbB2 were arranged in a heterodimer configuration and labeled with IRDye800. This near-infrared (NIR) contrast agent was topically administered to patients with Barrett's esophagus (BE) undergoing either endoscopic therapy or surveillance. Fluorescence images were collected using a flexible fiber accessory passed through the instrument channel of an upper gastrointestinal endoscope. Fluorescence images were collected from 31 BE patients. A deep learning model was used to segment the target (T) and background (B) regions. RESULTS: The mean target-to-background (T/B) ratio was significantly greater for high grade dysplasia (HGD) and EAC versus BE, low grade dysplasia (LGD), and squamous epithelium. At a T/B ratio of 1.5, sensitivity and specificity of 94.1 % and 92.6 %, respectively, were achieved for the detection of Barrett's neoplasia with an area under the curve of 0.95. No adverse events attributed to the heterodimer were found. EGFR and ErbB2 expression were validated in the resected specimens. CONCLUSIONS: This "first-in-human" clinical study demonstrates the feasibility of detection of early Barrett's neoplasia using a NIR-labeled peptide heterodimer.

Membrane Bound Peroxiredoxin-1 Serves as a Biomarker for In Vivo Detection of Sessile Serrated Adenomas.

Aim: Sessile serrated adenomas (SSAs) are premalignant lesions driven by the BRAFV600E mutation to give rise to colorectal cancers (CRCs). They are often missed during white light colonoscopy because of their subtle appearance. Previously, a fluorescently labeled 7mer peptide KCCFPAQ was shown to detect SSAs in vivo. We aim to identify the target of this peptide. Results: Peroxiredoxin-1 (Prdx1) was identified as the binding partner of the peptide ligand. In vitro binding assays and immunofluorescence staining of human colon specimens ex vivo supported this result. Prdx1 was overexpressed on the membrane of cells with the BRAFV600E mutation, and this effect was dependent on oxidative stress. RKO cells harboring the BRAFV600E mutation and human SSA specimens showed higher oxidative stress as well as elevated levels of Prdx1 on the cell membrane. Innovation and Conclusion: These results suggest that Prdx1 is overexpressed on the cell surface in the presence of oxidative stress and can serve as an imaging biomarker for in vivo detection of SSAs. Antioxid. Redox Signal. 36, 39-56.

Per-oral Endoscopic Myotomy Biopsies of Achalasia Patients Reveal Schwann Cell Depletion in the Muscularis Propria.

Achalasia is a neurodegenerative condition resulting in abnormal lower esophageal sphincter relaxation and impaired upstream esophageal body peristalsis.1 The pathophysiology and natural history of achalasia remain unclear, and evaluation of the histopathogenesis of achalasia has traditionally been challenging because the esophageal wall muscularis propria is not typically accessible via routine endoscopic biopsies.

Evidence of Duodenal Epithelial Barrier Impairment and Increased Pyroptosis in Patients With Functional Dyspepsia on Confocal Laser Endomicroscopy and "Ex Vivo" Mucosa Analysis.

INTRODUCTION: Duodenal epithelial barrier impairment and immune activation may play a role in the pathogenesis of functional dyspepsia (FD). This study was aimed to evaluate the duodenal epithelium of patients with FD and healthy individuals for detectable microscopic structural abnormalities. METHODS: This is a prospective study using esophagogastroduodenoscopy enhanced with duodenal confocal laser endomicroscopy (CLE) and mucosal biopsies in patients with FD (n = 16) and healthy controls (n = 18). Blinded CLE images analysis evaluated the density of epithelial gaps (cell extrusion zones), a validated endoscopic measure of the intestinal barrier status. Analyses of the biopsied duodenal mucosa included standard histology, quantification of mucosal immune cells/cytokines, and immunohistochemistry for inflammatory epithelial cell death called pyroptosis. Transepithelial electrical resistance (TEER) was measured using Ussing chambers. Epithelial cell-to-cell adhesion proteins expression was assessed by real-time polymerase chain reaction. RESULTS: Patients with FD had significantly higher epithelial gap density on CLE in the distal duodenum than that of controls (P = 0.002). These mucosal abnormalities corresponded to significant changes in the duodenal biopsy samples of patients with FD, compared with controls, including impaired mucosal integrity by TEER (P = 0.009) and increased number of epithelial cells undergoing pyroptosis (P = 0.04). Reduced TEER inversely correlated with the severity of certain dyspeptic symptoms. Furthermore, patients with FD demonstrated altered duodenal expression of claudin-1 and interleukin-6. No differences in standard histology were found between the groups. DISCUSSION: This is the first report of duodenal CLE abnormalities in patients with FD, corroborated by biopsy findings of epithelial barrier impairment and increased cell death, implicating that duodenal barrier disruption is a pathogenesis factor in FD and introducing CLE a potential diagnostic biomarker in FD.

Integrated Imaging Methodology Detects Claudin-1 Expression in Premalignant Nonpolypoid and Polypoid Colonic Epithelium in Mice.

OBJECTIVES: Conventional colonoscopy with white light illumination detects colonic adenomas based on structural changes alone and is limited by a high miss rate. We aim to demonstrate an integrated imaging strategy that combines wide-field endoscopy and confocal endomicroscopy in real time to visualize molecular expression patterns in vivo to detect premalignant colonic mucosa. METHODS: A peptide specific for claudin-1 is labeled with Cy5.5 and administrated intravenously in genetically engineered mice that develop adenomas spontaneously in the distal colon. Wide-field endoscopy is used to identify the presence of nonpolypoid and polypoid adenomas. Anatomic landmarks are used to guide placement of a confocal endomicroscope with side-view optics to visualize claudin-1 expression patterns with subcellular resolution. RESULTS: Wide-field fluorescence images show peak uptake in colon adenoma at ∼1 hour after systemic peptide administration, and lesion margins are clearly defined. Further examination of the lesion using a confocal endomicroscope shows dysplastic crypts with large size, elongated shape, distorted architecture, and variable dimension compared with normal. The mean fluorescence intensity is significantly higher for dysplasia than normal. Increased claudin-1 expression in dysplasia vs normal is confirmed ex vivo, and the binding pattern is consistent with the in vivo imaging results. DISCUSSION: Wide-field endoscopy can visualize molecular expression of claudin-1 in vivo to localize premalignant colonic mucosa, and confocal endomicroscopy can identify subcellular feature to distinguish dysplasia from normal.

Detection of colonic neoplasia in vivo using near-infrared-labeled peptide targeting cMet.

White light colonoscopy is widely used to detect colorectal polyps, but flat and depressed lesions are often missed. Here, we report a molecular imaging strategy to potentially improve diagnostic performance by developing a fluorescently-labeled peptide specific for cMet. This 7mer is conjugated to Cy5.5, a near-infrared (NIR) cyanine dye. Specific binding to cMet was confirmed by cell staining, knockdown, and competition assays. The probe showed high binding affinity (kd = 57 nM) and fast onset (k = 1.6 min) to support topical administration in vivo. A mouse model (CPC;Apc) that develops spontaneous adenomas that overexpress cMet was used to demonstrate feasibility for real time in vivo imaging. This targeting ligand showed significantly higher target-to-background (T/B) ratio for polypoid and non-polypoid lesions by comparison with a scrambled control peptide. Immunofluorescence staining on human colon specimens show significantly greater binding to tubular and sessile serrated adenomas versus hyperplastic polyps and normal mucosa. These results demonstrate a peptide specific for cMet that is promising for endoscopic detection of pre-malignant lesions and guiding of tissue biopsy.

Autoimmune Gastritis.

CONTEXT.­: Autoimmune gastritis (AG) is a corpus-restricted chronic atrophic gastritis associated with intrinsic factor deficiency, either with or without pernicious anemia. Autoimmune gastritis is a microscopic disease because patients present with no or vague symptoms, and clinicians rarely find endoscopic changes. Autoimmune gastritis only becomes a clinical disease when pathologists diagnose it in gastric biopsies performed for a variety of clinical indications. Unfamiliarity with this disease can result in misdiagnosis of patients, and thus inadequate patient management. OBJECTIVE.­: To review the pathogenesis, clinical features, diagnostic criteria, differential diagnoses, sequelae, and surveillance recommendations for AG. DATA SOURCES.­: The sources of the study include a review of the pertinent literature for AG. CONCLUSIONS.­: Autoimmune gastritis is an important disease characterized by a loss of oxyntic mucosa and presence of metaplastic epithelium and enterochromaffin-like cell hyperplasia. Awareness and proper diagnosis are critical to prevent mismanagement of patients.

Sorafenib encapsulated in nanocarrier functionalized with glypican-3 specific peptide for targeted therapy of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is the fifth most common cancer in the world with increasing incidence. Chemotherapy is required for HCC patients after receiving surgical resection. Serious off-target induced side effects and systemic toxicity limit the clinical utility of drugs. Targeting therapeutic nanomedicine is an innovative strategy for enhancing drug delivery efficiency and reducing side effects. Here, we successfully formulated nanocarriers to encapsulate sorafenib, an FDA approved drug for treatment of HCC. Sorafenib is encapsulated with an entrapment efficiency >80% over 20 days. The effective aqueous solubility is improved over 1900-fold. The release ratio in vitro is characterized by a half-life of T1/2 = 22.7 h. The peak target-to-background ratio for nanocarrier uptake by tumor occurs at 24 h post-injection, and is significantly greater for the target peptide versus controls. Ex vivo biodistribution confirms the in vivo results. Tumor regression is significantly greater for the target peptide versus controls after 21 days of therapy. No acute toxicity is found by blood chemistry or necropsy. In summary, a peptide specific for GPC3 has been identified, and used to modify the surface of a nanocarrier that encapsulates sorafenib with high entrapment efficiency. Regression of HCC xenograft tumors showed promise for targeted drug delivery.

Identification of Tumor Specific Peptide as EpCAM Ligand and Its Potential Diagnostic and Therapeutic Clinical Application.

Tumor targeting agents are being developed for early tumor detection and therapeutics. We previously identified the peptide SNFYMPL (SNF*) and demonstrated its specific binding to human esophageal specimens of high-grade dysplasia (HGD) and adenocarcinoma with imaging ex vivo. Here, we aim to identify the target for this peptide and investigate its potential applications in imaging and drug delivery. With SNF* conjugated affinity chromatography, mass spectrum, Western blot, enzyme-linked immunosorbent assay (ELISA), and molecular docking, we found that the epithelial cell adhesion molecule (EpCAM) was the potential target of SNF*. Next, we showed that FITC-labeled SNF* (SNF*-FITC) colocalized with EpCAM antibody on the surface of esophageal adenocarcinoma cells OE33, and SNF*-FITC binding patterns significantly changed after EpCAM knockdown or exogenous EpCAM transfection. With the data from TCGA, we demonstrated that EpCAM was overexpressed in 17 types of cancers. Using colon and gastric adenocarcinoma cells and tissues as examples, we found that SNF*-FITC bound in a pattern was colocalized with EpCAM antibody, and the SNF* binding did not upregulate the EpCAM downstream Wnt signals. Subsequently, we conjugated SNF* with our previously constructed poly(histidine)-PEG/DSPE copolymer micelles. SNF* labeling significantly improved the micelle binding with colon and gastric adenocarcinoma cells in vitro, and enhanced the antitumor effects and decreased the toxicities of the micelles in vivo. In conclusion, we identified and validated SNF* as a specific peptide for EpCAM. The future potential use of SNF* peptide in multiple tumor surveillance and tumor-targeted therapeutics was demonstrated.

Disrupting Inflammation-Associated CXCL8-CXCR1 Signaling Inhibits Tumorigenicity Initiated by Sporadic- and Colitis-Colon Cancer Stem Cells.

Dysfunctional inflammatory pathways are associated with an increased risk of cancer, including colorectal cancer. We have previously identified and enriched for a self-renewing, colon cancer stem cell (CCSC) subpopulation in primary sporadic colorectal cancers (CRC) and a related subpopulation in ulcerative colitis (UC) patients defined by the stem cell marker, aldehyde dehydrogenase (ALDH). Subsequent work demonstrated that CCSC-initiated tumors are dependent on the inflammatory chemokine, CXCL8, a known inducer of tumor proliferation, angiogenesis and invasion. Here, we use RNA interference to target CXCL8 and its receptor, CXCR1, to establish the existence of a functional signaling pathway promoting tumor growth initiated by sporadic and colitis CCSCs. Knocking down either CXCL8 or CXCR1 had a dramatic effect on inhibiting both in vitro proliferation and angiogenesis. Likewise, tumorigenicity was significantly inhibited due to reduced levels of proliferation and angiogenesis. Decreased expression of cycle cell regulators cyclins D1 and B1 along with increased p21 levels suggested that the reduction in tumor growth is due to dysregulation of cell cycle progression. Therapeutically targeting the CXCL8-CXCR1 signaling pathway has the potential to block sustained tumorigenesis by inhibiting both CCSC- and pCCSC-induced proliferation and angiogenesis.

Approach to the Liver Biopsy in the Patient With Chronic Low-Level Aminotransferase Elevations.

Pathologists sometimes encounter a liver biopsy from an asymptomatic patient with unexplained low-level parenchymal liver enzyme elevations. These biopsies often have minor histologic changes but are otherwise almost entirely normal. This can lead to the quandary of whether or not the features are clinically meaningful and how one must formulate a diagnosis from the possibly nonspecific findings of a near-normal biopsy. The following discussion focuses on the histologic changes that can be seen in these biopsies and the practical issues involved in making a diagnosis that provides useful information to the clinician. The literature and textbooks addressing the histologic and clinical features of these cases are reviewed with an emphasis on the clinical implications of finding nonspecific histologic alterations in these patients.

Mid- and Deep-Zone Gastritis: A Histologic Pattern Associated With Autoimmune Disease but Distinct From Autoimmune Atrophic Gastritis.

OBJECTIVES: We sought to characterize a histologic pattern of mid- and deep-zone gastritis, distinct from the typical pattern of Helicobacter pylori or autoimmune gastritis and to see if it had any clinicopathologic association(s). METHODS: We analyzed inflammatory patterns and composition, excluded autoimmune gastritis using immunohistochemistry, and reviewed the medical record for demographics, medical/surgical history, presenting symptoms, endoscopic findings, and medications for 28 cases. RESULTS: All cases had inflammation in the middle and/or deep mucosal zones with sparing of the superficial/pit compartment. Subfeatures included corpus or antral predominance, pangastric involvement, prominence of a subset(s) of inflammatory cells, and degree of epithelial injury. Of 28 patients, 13 had autoimmune disease(s), autoantibodies, or both. There was no other unifying clinical feature. CONCLUSIONS: This unique pattern of gastritis should be distinguished from other entities such as H pylori and autoimmune gastritis. At least a subset may be an autoimmune condition different from classic autoimmune gastritis.

Multiplexed Targeting of Barrett's Neoplasia with a Heterobivalent Ligand: Imaging Study on Mouse Xenograft in Vivo and Human Specimens ex Vivo.

Esophageal adenocarcinoma (EAC) is a molecularly heterogeneous disease that is rising rapidly in incidence and has poor prognosis. We developed a heterobivalent peptide to target detection of early Barrett's neoplasia by combining monomer heptapeptides specific for either EGFR or ErbB2 in a heterodimer configuration. The structure of a triethylene glycol linker was optimized to maximize binding interactions to the surface receptors on cells. The Cy5.5-labeled heterodimer QRH*-KSP*-E3-Cy5.5 demonstrated specific binding to each target and showed 3-fold greater fluorescence intensity and 2-fold higher affinity compared with those of either monomer alone. Peak uptake in xenograft tumors was observed at 2 h postinjection with systemic clearance by ∼24 h in vivo. Furthermore, ligand binding was evaluated on human esophageal specimens ex vivo, and 88% sensitivity and 87% specificity were found for the detection of either high-grade dysplasia (HGD) or EAC. This peptide heterodimer shows promise for targeted detection of early Barrett's neoplasia in clinical study.

The microscopic anatomy of the esophagus including the individual layers, specialized tissues, and unique components and their responses to injury.

The esophagus, a straight tube that connects the pharynx to the stomach, has the complex architecture common to the rest of the gastrointestinal tract with special differences that relate to its function as a conduit of ingested substances. For instance, it has submucosal glands that are unique and have a specific protective function. It has a squamous lining that exists nowhere else in the gut except the anus and it has a different submucosal nerve plexus when compared to the stomach and intestines. All of the layers of the esophageal wall and the specialized structures including blood and lymphatic vessels and nerves have specific responses to injury. The esophagus also has unique features such as patches of gastric mucosa called inlet patches at the very proximal part and it has a special sphincter mechanism at the most distal aspect. This review covers the normal microscopic anatomy of the esophagus and the patterns of reaction to stress and injury of each layer and each special structure.

Melanoma induced immunosuppression is mediated by hematopoietic dysregulation.

Tumors are associated with expansion of immunosuppressive cells such as tumor associated macrophages (TAMs), regulatory T cells (Tregs) and myeloid derived suppressor cells (MDSCs). These cells promote tumor growth, angiogenesis, metastasis and immune escape. Cancer patients frequently present symptoms such as anemia, leukocytosis and/or cytopenia; associated with poor prognosis. To uncover tumor-mediated hematopoietic abnormalities and identify novel targets that can be harnessed to improve tumor-specific immune responses, we investigated the hematopoietic stem and progenitor cell compartment in melanoma bearing mice. We show that melanoma growth results in expansion of myeloid lineages such as MDSCs, macrophages and DCs along with a reduction in mature RBCs and platelets. Mature B lymphocytes in the blood and BM of melanoma mice were also reduced. Mice bearing melanoma showed extramedullary hematopoiesis in the spleen. Increased expansion of myeloid lineages occurred directly at the level of stem and progenitor cells. The reduction in mature B lymphocytes resulted from a block at the Pro-B cell stage in the bone marrow. Addition of recombinant IL-3 to bone marrow cells resulted in the expansion of committed myeloid progenitors including common myeloid precursors, granulocyte-monocyte precursors and megakaryocyte-erythrocyte precursors. In vivo, IL-3 receptor stimulation in melanoma bearing mice using an IL-3 antibody also resulted in a robust expansion of committed myeloid progenitors and hematopoietic stem cells. Collectively our findings demonstrate that tumor growth plays a pivotal role in reprogramming the host immune system by impacting hematopoiesis directly at the level of stem cell compartment.

Identification, isolation and characterization of human LGR5-positive colon adenoma cells.

The intestine is maintained by stem cells located at the base of crypts and distinguished by the expression of LGR5. Genetically engineered mouse models have provided a wealth of information about intestinal stem cells, whereas less is known about human intestinal stem cells owing to difficulty detecting and isolating these cells. We established an organoid repository from patient-derived adenomas, adenocarcinomas and normal colon, which we analyzed for variants in 71 colorectal cancer (CRC)-associated genes. Normal and neoplastic colon tissue organoids were analyzed by immunohistochemistry and fluorescent-activated cell sorting for LGR5. LGR5-positive cells were isolated from four adenoma organoid lines and were subjected to RNA sequencing. We found that LGR5 expression in the epithelium and stroma was associated with tumor stage, and by integrating functional experiments with LGR5-sorted cell RNA sequencing data from adenoma and normal organoids, we found correlations between LGR5 and CRC-specific genes, including dickkopf WNT signaling pathway inhibitor 4 (DKK4) and SPARC-related modular calcium binding 2 (SMOC2). Collectively, this work provides resources, methods and new markers to isolate and study stem cells in human tissue homeostasis and carcinogenesis.

Use of Appropriate Surveillance for Patients With Nondysplastic Barrett's Esophagus.

BACKGROUND & AIMS: Barrett's esophagus (BE) is a precursor to esophageal adenocarcinoma (EAC). Guidelines recommend that patients with nondysplastic BE (NDBE) undergo surveillance endoscopy every 3-5 years. We aimed to identify factors associated with surveillance endoscopy of patients with NDBE and identify trends in appropriate surveillance endoscopy of NDBE at a large tertiary care center. METHODS: We performed a retrospective analysis of data from a Barrett's Esophagus Registry, identifying patients with NDBE who underwent endoscopy in 2002 or later. We identified patients with NDBE and collected data on length of BE segment, esophageal lesions, demographic features, medications, histology findings, comorbidities, development of EAC, and dates of follow-up endoscopies. We defined appropriate surveillance as 3-5 years between 2nd and 3rd endoscopies, over-utilizers as patients who had less than 3 years between their 2nd and 3rd endoscopies, under-utilizers as patients who had more than 5 years between their 2nd and 3rd endoscopies; and never-surveilled as patients who never received a 2nd endoscopy. The primary outcomes were effects of patient factors, year, and referring providers on appropriateness of surveillance intervals. RESULTS: We identified 477 patients with NDBE. Only 15.9% had appropriate surveillance; 37.9% were over-utilizers 15.7% were under-utilizers and 30.4% were never surveilled. Patients were less likely to be over-surveilled if their primary care physician referred them for their 3rd endoscopy instead of a gastroenterologist (adjusted odds ratio, 0.51; 95% CI, 0.27-0.95). Male patients or those with an increased number of comorbidities were more likely to be under-surveilled or never-surveilled, whereas patients with long BE segment were more likely to be over-surveilled. CONCLUSIONS: In a retrospective analysis of data from a registry of patients with BE, we found that less than 16% receive appropriate surveillance for NDBE. A primary care provider in the same health system as the endoscopy clinic reduced risk of over-surveillance. This could reflect better coordination of care between specialists and primary care providers.

Chronic Colitis in Biopsy Samples: Is It Inflammatory Bowel Disease or Something Else?

Chronic colitis, regardless of type, is defined histologically by chronic inflammation, mainly plasmacytosis, in the lamina propria. Specific diagnosis of chronic colitides in biopsies can be challenging for practicing pathologists. This article focuses on discussing specific histologic features in biopsies of the inflammatory bowel diseases (IBDs), including ulcerative colitis, Crohn colitis, and colitis of indeterminate type. It also offers suggestions as to how to separate the IBDs from other chronic colitides, such as lymphocytic colitis, collagenous colitis, diverticular disease-associated colitis, diversion colitis, and chronic colitides that are due to drugs. Normal histology in colon biopsies is also briefly discussed.