Refractory sprue, coeliac disease, and enteropathy-associated T-cell lymphoma. French Coeliac Disease Study Group

The Rising Incidence and Poor Outcomes of Enteropathy-Associated T-Cell Lymphoma

INTRODUCTION

Enteropathy-associated T-cell lymphoma (EATL) is associated with celiac disease. With the rising prevalence of celiac disease, we hypothesized that the prevalence of EATL is also increasing.

METHODS

We used the Surveillance, Epidemiology, and End Results database, which is a population-based US cancer surveillance program. We used the ICD-0-3 code 9717/3 to identify patients with EATL diagnosed between 2000 and 2020. Incidence rates were calculated using the SEER*Stat software, and annual percent change was calculated using the Joinpoint software. Log-rank tests were used to evaluate for significant difference in survival curves between groups. A Cox proportional hazards regression model was used for continuous variables and quantifying association strength of predictors.

RESULTS

A total of 463 cases of EATL were identified (273 male, 190 female) with a median age of 65 (range 23-90+) years. Most of the cases were at an advanced stage at diagnosis and were treated with a combination of surgery and chemotherapy. The median survival time was 6 months. The 2000-2020 age-adjusted incidence rate per 100,000 people was 0.014, and the incidence increased between 2000 and 2020, with an annual percent change of 2.58 ( P < 0.05). Increased age at diagnosis and lack of treatment had significant impacts on survival while sex, year of diagnosis, race, and time between diagnosis and treatment had no significant impact on survival.

DISCUSSION

There was a significant increase in the incidence of EATL in the United States between 2000 and 2020. Survival in this cancer remains poor and unchanged over the past 2 decades.

How Future Pharmacologic Therapies for Celiac Disease Will Complement the Gluten-Free Diet

The only proven treatment for celiac disease is adherence to a strict, lifelong, gluten-free diet. However, complete dietary gluten avoidance is challenging and a substantial number of patients do not respond fully, clinically, or histologically, despite their best efforts. As celiac disease is common and its central pathophysiology is well elucidated, it has become attractive for drug development to address the limitations of dietary treatment. Most efforts address nonresponsive celiac disease, defined as continued symptoms and/or signs of disease activity despite a gluten-free diet, and the more severe forms of refractory celiac disease, types I and II. An increasing spectrum of therapeutic approaches target defined mechanisms in celiac disease pathogenesis and some have advanced to current phase 2 and 3 clinical studies. We discuss these approaches in terms of potential efficiency, practicability, safety, and need, as defined by patients, regulatory authorities, health care providers, and payors.

Advances in Nonresponsive and Refractory Celiac Disease

Nonresponsive celiac disease (CeD) is relatively common. It is generally attributed to persistent gluten exposure and resolves after correction of diet errors. However, other complications of CeD and disorders clinically mimicking CeD need to be excluded. Novel therapies are being evaluated to facilitate mucosal recovery, which might benefit patients with nonresponsive CeD. Refractory CeD (RCeD) is rare and is divided into 2 types. The etiology of type I RCeD is unclear. A switch to gluten-independent autoimmunity is suspected in some patients. In contrast, type II RCeD represents a low-grade intraepithelial lymphoma. Type I RCeD remains a diagnosis of exclusion, requiring ruling out gluten intake and other nonmalignant causes of villous atrophy. Diagnosis of type II RCeD relies on the demonstration of a clonal population of neoplastic intraepithelial lymphocytes with an atypical immunophenotype. Type I RCeD and type II RCeD generally respond to open-capsule budesonide, but the latter has a dismal prognosis due to severe malnutrition and frequent progression to enteropathy-associated T-cell lymphoma; more efficient therapy is needed.

Flow cytometry for the assessment and monitoring of aberrant intraepithelial lymphocytes in non-responsive celiac disease and non-celiac enteropathies

BACKGROUND

Few data are available on flow cytometry (FC) for monitoring intraepithelial lymphocytes (IELs) in refractory celiac disease (RCD), non-responsive celiac disease (NRCD), and non-celiac enteropathies (NCEs).

AIMS

1) To investigate the significance of monitoring IELs immunophenotype with FC in patients with NRCD, RCD and NCEs; 2) to evaluate FC concordance with immunohistochemistry (IHC) and γ-TCR clonality analysis.

METHODS

Patients investigated between January-2012 and February-2023 were divided into two groups: 1)confirmed RCD or NRCD being investigated for persistent symptoms and suspected complications of celiac disease (CD); 2)NCEs lacking clinical/histological response. Clinical/molecular features and outcomes were retrospectively collected and analysed according to presence/absence of aberrant IELs on FC (cut-off≥20 % CD103+sCD3-CD8-iCD3+ IELs).

RESULTS

52 patients (18 RCD,21 NRCD,13 NCEs; 38F, 55±13 years; median follow-up 30 months, IQR 2-58) underwent 100 FC IELs determinations. 22/52 had ≥2 FC determinations and IEL phenotype remained unchanged over time in all them (κ=1.00). Aberrant IEL phenotype in CD was associated with increased mortality (HR 4.2, 95 % CI 1.5-11.9, p < 0.01). No patients with NCEs had an aberrant IEL phenotype at FC, although 3/13 developed lymphoma and 4/13 died. Concordance of FC was fair with both IHC (κ=0.40) and γ-TCR clonality analysis (κ=0.22).

CONCLUSION

FC is accurate for assessing and monitoring IEL phenotype and providing important prognostic information in celiac patients. Further study is needed on its role in NCEs.

Guidelines for best practices in monitoring established coeliac disease in adult patients

Coeliac disease (CeD) is an immunological disease triggered by the consumption of gluten contained in food in individuals with a genetic predisposition. Diagnosis is based on the presence of small bowel mucosal atrophy and circulating autoantibodies (anti-type 2 transglutaminase antibodies). After diagnosis, patients follow a strict, life-long gluten-free diet. Although the criteria for diagnosis of this disease are well defined, the monitoring phase has been studied less and there is a lack of specific guidelines for this phase. To develop a set of clinical guidelines for CeD monitoring, we followed the Grading of Recommendations Assessment, Development and Evaluation methodology. Statements and recommendations with the level of evidence were developed and approved by the working group, which comprised gastroenterologists, pathologists, dieticians and biostatisticians. The proposed guidelines, endorsed by the North American and European coeliac disease scientific societies, make recommendations for best practices in monitoring patients with CeD based on the available evidence. The evidence level is low for many topics, suggesting that further research in specific aspects of CeD would be valuable. In conclusion, the present guidelines support clinicians in improving CeD treatment and follow-up and highlight novel issues that should be considered in future studies.

Cross-sectional imaging: current status and future potential in adult celiac disease

Celiac disease (CD), triggered by exposure to gluten in genetically susceptible individuals, is an immune-mediated small bowel disease affecting about 1% of the population worldwide. But the prevalence of CD varies with age, sex, and location. A strict gluten-free diet remains the primary treatment for CD, currently. Most of patients with CD respond well to gluten-free diet with good prognosis, while some patients fail to get symptomatic relief or histological remission (e.g., nonresponsive or refractory CD). Because of heterogeneous clinical appearance, the diagnosis of CD is difficult. Moreover, malignant complications and poor outcomes accompanied with refractory CD present great challenges in disease management. Over the past three decades, cross-sectional imaging techniques (computed tomography [CT] and magnetic resonance imaging [MRI]) play an important role in small bowel inflammatory and neoplastic diseases. Compared with endoscopic techniques, cross-sectional imaging permits clearly presentation of both intraluminal and extraluminal abnormalities. It provides vascular and functional information, thus improving the possibility as diagnostic and follow-up tool. The value of cross-sectional imaging for patients with suspected or confirmed CD has been gradually demonstrated. Studies revealed that certain features suggested by cross-sectional imaging could help to establish the early diagnosis of CD. Besides, the potential contributions of cross-sectional imaging may lie in the evaluation of disease activity and severity, which helps guiding management strategies. The purpose of this review is to provide current overviews and future directions of cross-sectional imaging in adult CD, thus facilitating the understanding and application in clinical practice. CLINICAL RELEVANCE STATEMENT: In this review, we systematically summarized the existing knowledge of cross-sectional imaging in adult CD and analyzed their possible roles in clinical practice, including disease diagnosis, complication identification, treatment evaluation, and prognostic prediction. KEY POINTS: • Regarding a condition described as "celiac iceberg", celiac disease remains underdiagnosed and undertreated. • Cross-sectional imaging is helpful in clinical management of celiac disease, including disease diagnosis, complication identification, treatment evaluation, and prognostic prediction. • Cross-sectional imaging should be considered as the valuable examination in patients suspected from celiac disease.

Refractory celiac disease and its mimickers: a review on pathogenesis, clinical-pathological features and therapeutic challenges

Refractory celiac disease (RCD) and enteropathy-associated T-cell lymphoma (EATL) are rare, yet severe complications of celiac disease (CD). Over the last decades, several studies have addressed the biology and clinical-pathological features of such conditions, highlighting unique disease patterns and recurrent genetic events. Current classification proposals identify two forms of RCD, namely: (i) type 1 RCD (RCD-I), characterized by phenotypically normal intra-epithelial lymphocytes (IELs); and (ii) type 2 RCD (RCD-II), featuring phenotypically aberrant IELs. While RCD-I likely represents a gluten-independent dysimmune reaction against small bowel epithelial cells, RCD-II is better considered an in situ aggressive T-cell lymphoma, with high rates of progression to overt EATL. The diagnosis of RCD and EATL is often challenging, due to misleading clinical-pathological features and to significant overlap with several CD-unrelated gastro-intestinal disorders. Similarly, the treatment of RCD and EATL is an unmet clinical need for both gastroenterologists and hematologists. Moving from such premises, this review aims to provide a comprehensive view of RCD and EATL, specifically considering their pathogenesis and the many still open issues concerning their diagnosis and clinical management.

Persistent villous atrophy predicts development of complications and mortality in adult patients with coeliac disease: a multicentre longitudinal cohort study and development of a score to identify high-risk patients

OBJECTIVE

Persistent villous atrophy (pVA) in coeliac disease (CD) despite a gluten-free diet (GFD) has unclear meaning. We aimed to (i) study the relationship between pVA and long-term outcomes and (ii) develop a score to identify patients at risk of pVA.

DESIGN

This is a multicentre retrospective-prospective study consisting of a study cohort (cohort 1) and an external validation cohort (cohort 2) of patients with biopsy-proven CD diagnosed between 2000 and 2021. Cohort 1 was used to (i) compare long-term outcomes between patients with and without pVA (Marsh ≥3a) at follow-up biopsy and (ii) to develop a score to evaluate the risk of pVA, which was validated in cohort 2.

RESULTS

Of 2211 patients, 694 (31%) underwent follow-up duodenal biopsy and were included in the study cohort (491F, 44±16 years). 157/694 (23%) had pVA. Risk of complications (HR 9.53, 95% CI 4.77 to 19.04, p<0.001) and mortality (HR 2.93, 95% CI 1.43 to 6.02, p<0.01) were increased in patients with pVA. A 5-point score was developed and externally validated (receiver operating characteristic area under the curve 0.78, 95% CI 0.68 to 0.89) to stratify patients by risk of pVA: low (0-1 points, 5% pVA), intermediate (2 points, 16% pVA) and high (3-5 points, 73% pVA). Predictors for pVA used in the score were age at diagnosis ≥45 years (OR 2.01, 95% CI 1.21 to 3.34, p<0.01), classical pattern of CD (OR 2.14, 95% CI 1.28 to 3.58, p<0.01), lack of clinical response to GFD (OR 2.40, 95% CI 1.43 to 4.01, p<0.001) and poor GFD adherence (OR 48.9, 95% CI 26.1 to 91.8, p<0.001).

CONCLUSIONS

Risk of complications and mortality were increased in patients with pVA. We developed a score to identify patients at risk of pVA and in need of histological reassessment and closer follow-up.

SOHO State of the Art Updates and Next Questions | Challenging Cases in Rare T-Cell Lymphomas

Mature T- and NK-cell neoplasms (MTNKN) collectively represent a rare disorder, representing less than 15% of all non-Hodgkin lymphoma (NHL) cases and qualifying for orphan disease designation by the U.S. Food and Drug Administration (FDA). These consist of 9 families in the fifth revised WHO classification of lymphoid neoplasms, which are made up of over 30 disease subtypes, underscoring the heterogeneity of clinical features, molecular biology, and genetics across this disease group. Moreover, the 5 most common subtypes (peripheral T-cell lymphoma, not otherwise specified; nodal TFH cell lymphoma, angioimmunoblastic type; extranodal NK-cell/T-cell lymphoma; adult T-cell leukemia/lymphoma; and ALK-positive or -negative anaplastic large cell lymphoma) comprise over 75% of MTNKN cases, so other subtypes are exceedingly rare in the context of all NHL diagnoses and consequently often lack consensus on best practices in diagnosis and management. In this review, we discuss the following entities-enteropathy-associated T-cell lymphoma (EATL), monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL), hepatosplenic T-cell lymphoma (HSTCL), subcutaneous panniculitis-like T-cell lymphoma (SPTCL), and primary cutaneous ɣδ T-cell lymphoma (PCGD-TCL) - with an emphasis on clinical and diagnostic features and options for management.

Old and New Adjunctive Therapies in Celiac Disease and Refractory Celiac Disease: A Review

Celiac disease (CD) is a chronic enteropathy caused by the ingestion of gluten in a genetically susceptible individual. Currently, a gluten-free diet (GFD) is the only recommended treatment. However, unintentional gluten ingestion or a persistent villous atrophy with malabsorption (regardless of a strict GFD) as in the case of Refractory Celiac Disease (RCD) represents a major issue. In this review, we have analysed and discussed data from both randomized controlled trials and observational studies concerning adjunctive therapies as well as novel therapies for the treatment of CD and RCD. The literature search was carried out through Medline and Scopus. In total, 2268 articles have been identified and 49 were included in this review (36 studies resulting from the search strategy and 13 from other sources). Today, GFD remains the only effective treatment, although steroids, mesalamine, and more recently biological therapies have found space in the complex management of RCD. Currently, studies evaluating the effectiveness of novel therapies are still limited and preliminary results have been controversial.

Diffuse intestinal ulcerations: Diagnostic challenge in a patient with complicated celiac disease

A 48‐year‐old female patient presented with longstanding unrecognized celiac disease (CD), a family history of CD, and a short duration of alarming symptoms. The diagnostic evaluation revealed the concomitant presence of small and large bowel ulcers raised a dilemma about differential diagnosis in her case. Pathologic examination of tissue specimens from the jejunal ulcer led to the diagnosis of enteropathy‐associated T‐cell lymphoma. In recent years, the availability of modern cross‐sectional imaging and endoscopy modalities has dramatically improved the detection and characterization of small bowel lesions. Characterization of small bowel ulcers by endoscopy and radiology imaging in a patient with suspected complicated CD (CCD) needs to be made in conjunction with all clinical factors, as there is a wide overlap of the possible etiologic factors. Enteropathy‐associated T‐cell lymphoma is a highly aggressive T‐cell lymphoma with a poor prognosis, since early diagnosis and appropriate treatment may be delayed due to nonspecific clinical and endoscopic presentation. Therefore, it is crucial to timely recognize patients with suspected CCD and properly navigate diagnostic imaging tools, acquire adequate biopsy, and perform immunophenotyping to set early diagnosis in patients with diffuse intestinal ulcers and CD.

Immunopathogenesis and environmental triggers in coeliac disease

Coeliac disease (CD) is a frequent immune enteropathy induced by gluten in genetically predisposed individuals. Its pathogenesis has been extensively studied and CD has emerged as a model disease to decipher how the interplay between environmental and genetic factors can predispose to autoimmunity and promote lymphomagenesis. The keystone event is the activation of a gluten-specific immune response that is driven by molecular interactions between gluten, the indispensable environmental factor, HLA-DQ2/8, the main predisposing genetic factor and transglutaminase 2, the CD-specific autoantigen. The antigluten response is however not sufficient to induce epithelial damage which requires the activation of cytotoxic CD8+ intraepithelial lymphocytes (IEL). In a plausible scenario, cooperation between cytokines released by gluten-specific CD4+ T cells and interleukin-15 produced in excess in the coeliac gut, licenses the autoimmune-like attack of the gut epithelium, likely via sustained activation of the Janus kinase-signal transducer and activator of transcription (JAK/STAT) pathway in IEL. Demonstration that lymphomas complicating CD arise from IEL that have acquired gain-of-function JAK1 or STAT3 mutations stresses the key role of this pathway and explains how gluten-driven chronic inflammation may promote this rare but most severe complication. If our understanding of CD pathogenesis has considerably progressed, several questions and challenges remain. One unsolved question concerns the considerable variability in disease penetrance, severity and presentation, pointing to the role of additional genetic and environmental factors that remain however uneasy to untangle and hierarchize. A current challenge is to transfer the considerable mechanistic insight gained into CD pathogenesis into benefits for the patients, notably to alleviate the gluten-free diet, a burden for many patients.

Review article: Follow-up of coeliac disease

Coeliac disease is a lifelong immune-mediated enteropathy with systemic features associated with increased morbidity and modestly increased mortality. Treatment with a strict gluten-free diet improves symptoms and mucosal damage but is not curative and low-level gluten intake is common despite strict attempts at adherence. Regular follow-up after diagnosis is considered best-practice however this is executed poorly in the community with the problem compounded by the paucity of data informing optimal approaches. The aim of dietary treatment is to resolve symptoms, reduce complication risk and improve quality of life. It follows that the goals of monitoring are to assess dietary adherence, monitor disease activity, assess symptoms and screen for complications. Mucosal disease remission is regarded a key measure of treatment success as healing is associated with positive health outcomes. However, persistent villous atrophy is common, even after many years of a gluten-free diet. As the clinical significance of asymptomatic enteropathy is uncertain the role for routine follow-up biopsies remains contentious. Symptomatic non-responsive coeliac disease is common and with systematic follow-up a cause is usually found. Effective models of care involving the gastroenterologist, dietitian and primary care doctor will improve the consistency of long-term management and likely translate into better patient outcomes. Identifying suitable treatment targets linked to long-term health is an important goal.

Cellular Origins and Pathogenesis of Gastrointestinal NK- and T-Cell Lymphoproliferative Disorders

The intestinal immune system, which must ensure appropriate immune responses to both pathogens and commensal microflora, comprises innate lymphoid cells and various T-cell subsets, including intra-epithelial lymphocytes (IELs). An example of innate lymphoid cells is natural killer cells, which may be classified into tissue-resident, CD56bright NK-cells that serve a regulatory function and more mature, circulating CD56dim NK-cells with effector cytolytic properties. CD56bright NK-cells in the gastrointestinal tract give rise to indolent NK-cell enteropathy and lymphomatoid gastropathy, as well as the aggressive extranodal NK/T cell lymphoma, the latter following activation by EBV infection and neoplastic transformation. Conventional CD4+ TCRαβ+ and CD8αβ+ TCRαβ+ T-cells are located in the lamina propria and the intraepithelial compartment of intestinal mucosa as type 'a' IELs. They are the putative cells of origin for CD4+ and CD8+ indolent T-cell lymphoproliferative disorders of the gastrointestinal tract and intestinal T-cell lymphoma, NOS. In addition to such conventional T-cells, there are non-conventional T-cells in the intra-epithelial compartment that express CD8αα and innate lymphoid cells that lack TCRs. The central feature of type 'b' IELs is the expression of CD8αα homodimers, seen in monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL), which primarily arises from both CD8αα+ TCRαβ+ and CD8αα+ TCRγδ+ IELs. EATL is the other epitheliotropic T-cell lymphoma in the GI tract, a subset of which arises from the expansion and reprograming of intracytoplasmic CD3+ innate lymphoid cells, driven by IL15 and mutations of the JAK-STAT pathway.

The global burden of coeliac disease: opportunities and challenges

Coeliac disease is a systemic disorder characterized by immune-mediated enteropathy, which is caused by gluten ingestion in genetically susceptible individuals. The clinical presentation of coeliac disease is highly variable and ranges from malabsorption through solely extra-intestinal manifestations to asymptomatic. As a result, the majority of patients with coeliac disease remain undiagnosed, misdiagnosed or experience a substantial delay in diagnosis. Coeliac disease is diagnosed by a combination of serological findings of disease-related antibodies and histological evidence of villous abnormalities in duodenal biopsy samples. However, variability in histological grading and in the diagnostic performance of some commercially available serological tests remains unacceptably high and confirmatory assays are not readily available in many parts of the world. Currently, the only effective treatment for coeliac disease is a lifelong, strict, gluten-free diet. However, many barriers impede patients' adherence to this diet, including lack of widespread availability, high cost, cross-contamination and its overall restrictive nature. Routine follow-up is necessary to ensure adherence to a gluten-free diet but considerable variation is evident in follow-up protocols and the optimal disease management strategy is not clear. However, these challenges in the diagnosis and management of coeliac disease suggest opportunities for future research.

Successful novel use of tofacitinib for type II refractory coeliac disease

Refractory coeliac disease (RCD) occurs when patients with confirmed CD have continuous or recurrent malabsorption and enteropathy after at least 12 months on a gluten-free diet. Differentiating between type I and type II RCD is key as the latter is associated with T-cell aberrancy and considered prelymphoma, with high mortality rates. Current treatment regimens for type II RCD include corticosteroids, biologics and chemotherapy, but there are no proven therapies for this serious condition. Our patient is a middle-aged woman who developed postpartum type II RCD. When she failed multiple drug classes, we did a trial of tofacitinib. Our clinical experience with use of a janus kinase inhibitor was successful, with no associated adverse events. This is the first report in the literature of RCD remission in response to tofacitinib. The use of this novel agent shows promise in reversing this potentially fatal condition.

Refractory Coeliac disease-a case series from Pakistan

Coeliac disease or gluten intolerance is a frequent cause of chronic diarrhoea leading to malabsorptive symptoms. Refractory coeliac disease is a rare entity, which is not only harder to diagnose but managing it can be challenging. We hereby present three such 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.

Oncogenetic landscape of lymphomagenesis in coeliac disease

OBJECTIVE

Enteropathy-associated T-cell lymphoma (EATL) is a rare but severe complication of coeliac disease (CeD), often preceded by low-grade clonal intraepithelial lymphoproliferation, referred to as type II refractory CeD (RCDII). Knowledge on underlying oncogenic mechanisms remains scarce. Here, we analysed and compared the mutational landscape of RCDII and EATL in order to identify genetic drivers of CeD-associated lymphomagenesis.

DESIGN

Pure populations of RCDII-cells derived from intestinal biopsies (n=9) or sorted from blood (n=2) were analysed by whole exome sequencing, comparative genomic hybridisation and RNA sequencing. Biopsies from RCDII (n=50), EATL (n=19), type I refractory CeD (n=7) and uncomplicated CeD (n=18) were analysed by targeted next-generation sequencing. Moreover, functional in vitro studies and drug testing were performed in RCDII-derived cell lines.

RESULTS

80% of RCDII and 90% of EATL displayed somatic gain-of-functions mutations in the JAK1-STAT3 pathway, including a remarkable p.G1097 hotspot mutation in the JAK1 kinase domain in approximately 50% of cases. Other recurrent somatic events were deleterious mutations in nuclear factor kappa-light-chain-enhancer of activated B-cells (NF-κB) regulators TNFAIP3 and TNIP3 and potentially oncogenic mutations in TET2, KMT2D and DDX3X. JAK1 inhibitors, and the proteasome inhibitor bortezomib could block survival and proliferation of malignant RCDII-cell lines.

CONCLUSION

Mutations activating the JAK1-STAT3 pathway appear to be the main drivers of CeD-associated lymphomagenesis. In concert with mutations in negative regulators of NF-κB, they may favour the clonal emergence of malignant lymphocytes in the cytokine-rich coeliac intestine. The identified mutations are attractive therapeutic targets to treat RCDII and block progression towards EATL.

Epstein-Barr Virus-positive Intestinal Diffuse Large B-cell Lymphoma in a Japanese Patient with Celiac Disease: First Reported Case and a Literature Review

A 60-year-old Japanese woman was diagnosed with celiac disease (CeD) and treated with a gluten-free diet. For five years, she had a good clinical course. However, she complained of inappetence and nausea. Colonoscopy revealed ulcerative tumors in the terminal ileum. A histological examination of biopsy specimens from the ulcerative tumor showed diffuse infiltration of large atypical lymphocytes. Immunohistologically, the atypical lymphoid cells were positive for cluster of differentiation (CD) 10 and CD20. Many Epstein-Barr virus-encoded small RNA (EBER)-positive atypical lymphocytes were detected by in situ hybridization. This represents the first reported case of Epstein-Barr virus-positive intestinal diffuse large B-cell lymphoma complicated with CeD.

Frontiers in Celiac Disease: Where Autoimmunity and Environment Meet

Celiac disease is a chronic, immune-mediated enteropathy driven by dietary gluten found in genetically susceptible hosts. It has a worldwide distribution, is one of the most common autoimmune disorders globally, and is the only autoimmune condition for which the trigger is known. Despite advances in characterizing mechanisms of disease, gaps in understanding of celiac disease pathogenesis remain. A "frontier" concept is considering what moves an HLA-DQ2 or DQ8-positive individual from asymptomatic gluten tolerance to celiac disease manifestation. In this arena, environmental triggers, including age at the time of initial gluten exposure, the occurrence of usual childhood viral infections, and microbiome alterations have emerged as key events in triggering the symptomatic disease. Pathologists play a major role in frontier aspects of celiac disease. This includes the discovery that duodenal mucosal histology in follow-up biopsies does not correlate with ongoing patient symptoms, antitissue transglutaminase antibody titers and diet adherence in celiac disease patients. Further, in light of recent evidence that the detection of monoclonal T-cell populations in formalin-fixed biopsies is not specific for type II refractory celiac disease, pathologists should resist performing such analyses until common causes of "apparent" refractoriness are excluded. The promise of therapies in celiac disease has led to clinical trials targeting many steps in the inflammatory cascade, which depend upon a pathologist's confirmation of the initial diagnosis and evaluation of responses to therapies. As pathologists continue to be active participants in celiac disease research, partnering with other stakeholders, we will continue to impact this important autoimmune disease.

Immunophenotyping of intraepithelial lymphocytes in canine chronic enteropathy and intestinal T-cell lymphoma using endoscopic samples

Human enteropathy-associated T-cell lymphoma (EATL) is considered to be derived from intraepithelial lymphocytes (IELs); however, the origin of canine intestinal T-cell lymphoma (ITCL) remains unclear. Histological, immunohistochemical, and clonality examinations were performed using endoscopically collected canine duodenum samples of mucosal lesions of chronic enteropathy (CE; 73 cases) and ITCL without transmural neoplastic mass lesions (64 cases). Histopathological examinations revealed the intraepithelial accumulation of lymphocytes (called "intraepithelial lymphocytosis") in 54/73 CE cases (74%) and the epitheliotropism of neoplastic lymphocytes in 63/64 ITCL cases (98%). Immunohistochemically, IELs in CE with intraepithelial lymphocytosis (IEL⁺CE) were diffusely immunopositive for CD3, with scattered immunopositivity for CD5, CD8, CD20, and granzyme B (GRB). The percentage of CD8⁺ in CD3⁺ IELs was significantly lower in IEL⁺CE than in CE without intraepithelial lymphocytosis (IEL^-CE). Double-labeling immunohistochemistry revealed a high percentage of GRB expression in CD8^- IEL among IEL⁺CE. Among 64 ITCL cases, CD3 was immunopositive in 64 (100%), CD5 in 22 (34%), CD8 in 8 (13%), CD20 in 12 (19%), CD30 in 13 (20%), and GRB in 49 (77%). In CD3⁺ cells, Ki67 immunopositivity was highest in ITCL, intermediate in IEL⁺CE, and lower in IEL^-CE. A clonal TCR gene rearrangement was detected in 1/19 IEL^-CE cases (5%), 15/54 IEL⁺CE (28%), and 38/58 ITCL (66%). These results indicate that the immunophenotype of canine ITCL (CD8^-GRB⁺) is similar to that of the increased IELs in CE. The high proliferative activity and clonality of T cells in IEL⁺CE suggest that canine ITCL originates from these IELs, similar to human EATL.

Primary Gastrointestinal T-Cell Lymphoma and Indolent Lymphoproliferative Disorders: Practical Diagnostic and Treatment Approaches

Simple Summary

It is challenging for pathologists to diagnose primary gastrointestinal T-cell neoplasms. Besides the rarity of the diseases, the small biopsy material makes it more difficult to differentiate between non-neoplastic inflammation and secondary involvement of extra gastrointestinal lymphoma. Since this group of diseases ranges from aggressive ones with a very poor prognosis to indolent ones that require caution to avoid overtreatment, the impact of the diagnosis on the patient is enormous. Although early treatment of aggressive lymphoma is essential, the treatment strategy is not well established, which is a problem for clinicians. This review provides a cross-sectional comparison of histological findings. Unlike previous reviews, we summarized up-to-date clinically relevant information including the treatment strategies as well as practical differential diagnosis based on thorough literature review.

Abstract

Primary gastrointestinal (GI) T-cell neoplasms are extremely rare heterogeneous disease entities with distinct clinicopathologic features. Given the different prognoses of various disease subtypes, clinicians and pathologists must be aware of the key characteristics of these neoplasms, despite their rarity. The two most common aggressive primary GI T-cell lymphomas are enteropathy-associated T-cell lymphoma and monomorphic epitheliotropic intestinal T-cell lymphoma. In addition, extranodal natural killer (NK)/T-cell lymphoma of the nasal type and anaplastic large cell lymphoma may also occur in the GI tract or involve it secondarily. In the revised 4th World Health Organization classification, indolent T-cell lymphoproliferative disorder of the GI tract has been incorporated as a provisional entity. In this review, we summarize up-to-date clinicopathological features of these disease entities, including the molecular characteristics of primary GI T-cell lymphomas and indolent lymphoproliferative disorders. We focus on the latest treatment approaches, which have not been summarized in existing reviews. Further, we provide a comprehensive review of available literature to address the following questions: How can pathologists discriminate subtypes with different clinical prognoses? How can primary GI neoplasms be distinguished from secondary involvement? How can these neoplasms be distinguished from non-specific inflammatory changes at an early stage?

Pitfalls in gastrointestinal tract haematopoietic lesions

Specimens from the gastrointestinal (GI) tract are among the most commonly encountered in routine pathology practice worldwide. It is well known that the luminal GI tract is home to various areas rich in mucosa-associated lymphoid tissue (MALT), whether native or acquired. The latter may be particularly problematic due to its well-known predisposing factors such as Helicobacter pylori infection and autoimmune conditions. Nevertheless, native GI structures are often the subject of query, particularly in conditions that may mimic lymphoproliferative conditions, including infectious and inflammatory diseases. Herein, we describe and share common clinicopathological findings in our daily practice that are challenging to distinguish from subtle low-grade neoplastic lymphoproliferative disorders.

Monomorphic Epitheliotropic Intestinal T-Cell Lymphoma in the Ileum with Successful Preoperative Endoscopic Evaluation

A 80-year-old man with the history of operations for gastric cancer and adhesive ileus developed abdominal pain. Positron emission computed tomography (CT) showed prominent wall thickening in the ileum with a maximal standardized uptake value of 12.1. Prior CT to diagnose adhesive ileus just taken only 4 months before did not show any masses in the abdomen. Single-balloon enteroscopy via colon showed a protruding mass at approximately 40–50 cm proximal point from the ileum end. Pathological examination of the biopsied specimen showed diffuse infiltration of medium- to large-sized atypical lymphocytes. Immunohistochemistry analysis showed that the atypical cells were positive for CD3 and CD56 and negative for CD8 and CD20. MIB-1 labeling index was extremely high as 80%. Under the diagnosis of intestinal T-cell lymphoma, the patient underwent tumorectomy, leading to the diagnosis of monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) after the negativity confirmation of Epstein-Barr virus-encoded mRNAs. The patient recovered with manageable complication and is going to receive chemotherapy. This is the first case of MEITL with extremely rapid progression in the distal ileum to be observed and diagnosed with single-balloon enteroscopy.

Clinical classification and long-term outcomes of seronegative coeliac disease: a 20-year multicentre follow-up study

BACKGROUND

Seronegative coeliac disease is poorly defined.

AIMS

To study clinical phenotypes and long-term outcomes of seronegative coeliac disease in a multicentre cohort over 20 years.

METHODS

Seronegative coeliac disease was diagnosed in HLA-DQ2/DQ8-positive patients with villous atrophy (VA), negative IgA endomysial (EmA), tissue transglutaminase (tTG) and deamidated-gliadin antibodies (DGP), clinical and histological response to a gluten-free diet (GFD), and no alternative causes for VA. In patients with IgA deficiency, coeliac disease was diagnosed through VA, positive IgG EmA/tTG/DGP and clinical/histological response to a GFD (coeliac disease+IgAd). Patients with seropositive coeliac disease served as controls.

RESULTS

Of 227 patients previously diagnosed with seronegative coeliac disease, true seronegative coeliac disease was confirmed in 84, coeliac disease+IgAd in 48, and excluded in 55. Lack of follow-up duodenal biopsy precluded diagnosing seronegative coeliac disease in 40 patients. 2084 patients with seropositive coeliac disease served as controls. True seronegative coeliac disease had more severe symptoms at diagnosis and a higher risk of complications (HR 10.87, 95% CI 6.11-19.33, P < 0.001) and mortality (HR 2.18, 95% CI 1.12-4.26, P < 0.01) than seropositive coeliac disease. There were no differences between true seronegative coeliac disease and coeliac disease+IgAd. On multivariate analysis, age at diagnosis, lack of clinical response to a GFD, true seronegative coeliac disease, coeliac disease+IgAd, and classical presentation predicted complications. Age at diagnosis, complications and absence of clinical response to a GFD predicted mortality.

CONCLUSIONS

Seronegative coeliac disease has a more aggressive disease phenotype than seropositive coeliac disease. These data argue against over-reliance on serology for the diagnosis of coeliac disease and support a strict clinical and histologic follow-up in seronegative coeliac disease.

The Progression of Celiac Disease, Diagnostic Modalities, and Treatment Options

Celiac disease (CD) is an autoimmune disorder that affects genetically predisposed individuals who are sensitive to gluten and related proteins. It affects children and adults with increasing prevalence in the older age groups. Both adaptive and innate immune responses play role in CD pathogenesis which results in damage of lamina propria and deposition of intraepithelial lymphocytes. There are other proposed mechanisms of CD pathogenesis like gastrointestinal infections, intestinal microbiota, and early introduction of gluten. The diagnosis of CD is based on clinical symptoms and serological testing, though a majority of cases are asymptomatic, and small intestinal biopsies are required to confirm the diagnosis. Celiac disease is generally associated with other autoimmune diseases, and it is advisable to test these patients for diseases like type 1 diabetes mellitus, Addison’s disease, thyroid diseases, inflammatory bowel disease, and autoimmune hepatitis. The patient with a new diagnosis of CD requires close follow-up after starting treatment to see symptom improvement and check dietary compliance. A newly diagnosed patient is advised to follow with a dietitian to better understand the dietary restrictions as about 20% of patients stay symptomatic even after starting treatment due to noncompliance or poor understanding of diet restrictions. The most effective treatment for CD is a gluten-free diet, but work on non-dietary therapy is in process and few medications are in the clinical trial phase.

The Risk of Malignancies in Celiac Disease-A Literature Review

Celiac disease (CeD) is an immune-mediated enteropathy precipitated by ingestion of gluten in genetically predisposed individuals. Considering that CeD affects approximately 1% of the Western population, it may be considered a global health problem. In the large majority of cases, CeD has a benign course, characterized by the complete resolution of symptoms and a normal life expectancy after the beginning of a gluten-free-diet (GFD); however, an increased risk of developing malignancies, such as lymphomas and small bowel carcinoma (SBC), has been reported. In particular, enteropathy-associated T-cell lymphoma (EATL), a peculiar type of T-cell lymphoma, is characteristically associated with CeD. Moreover, the possible association between CeD and several other malignancies has been also investigated in a considerable number of studies. In this paper, we aim to provide a comprehensive review of the current knowledge about the associations between CeD and cancer, focusing in particular on EATL and SBC, two rare but aggressive malignancies.

Bowel Histology of CVID Patients Reveals Distinct Patterns of Mucosal Inflammation

Diarrhea is the commonest gastrointestinal symptom in patients with common variable immunodeficiency (CVID). Different pathologies in patients' bowel biopsies have been described and links with infections have been demonstrated. The aim of this study was to analyze the bowel histology of CVID patients in the Royal-Free-Hospital (RFH) London CVID cohort. Ninety-five bowel histology samples from 44 adult CVID patients were reviewed and grouped by histological patterns. Reasons for endoscopy and possible causative infections were recorded. Lymphocyte phenotyping results were compared between patients with different histological features. There was no distinctive feature that occurred in most diarrhea patients. Out of 44 patients (95 biopsies), 38 lacked plasma cells. In 14 of 21 patients with nodular lymphoid hyperplasia (NLH), this was the only visible pathology. In two patients, an infection with Giardia lamblia was associated with NLH. An IBD-like picture was seen in two patients. A coeliac-like picture was found in six patients, four of these had norovirus. NLH as well as inflammation often occurred as single features. There was no difference in blood lymphocyte phenotyping results comparing groups of histological features. We suggest that bowel histology in CVID patients with abdominal symptoms falls into three major histological patterns: (i) a coeliac-like histology, (ii) IBD-like changes, and (iii) NLH. Most patients, but remarkably not all, lacked plasma cells. CVID patients with diarrhea may have an altered bowel histology due to poorly understood and likely diverse immune-mediated mechanisms, occasionally driven by infections.

Diagnosing coeliac disease: A literature review

Coeliac disease (CD) is an autoimmune gastroenteropathy triggered by gliadin and gliadin-tissue transglutaminase (tTG) complexes. CD is one of the few autoimmune diseases with an accurate, non-invasive serological test. Anti-endomysial, anti-tTG and anti-deaminated gliadin peptides (DGP) antibodies are currently used for serological tests with tTG ELISAs being the superior test. Duodenal biopsy, although invasive, is the gold standard for CD diagnosis. HLA genotyping and flow cytometry can also be used as supplementary tests. The incidence of CD is rising globally although the reasons for this remain unclear. In addition, the true incidence of coeliac disease in African populations remains unknown although recent work suggests that South African populations express the alleles associated with this disease. This review examines the pathogenesis and diagnosis of coeliac disease and considers novel and innovative biomarkers in its diagnosis specifically in an African population.

Histopathology of Celiac Disease. Position Statements of the Italian Group of Gastrointestinal Pathologists (GIPAD-SIAPEC)

Celiac Disease (CeD) is an immune-mediated inflammatory disorder of the small intestine, affecting genetically susceptible individuals when exposed to gluten. Small intestinal biopsy interpretation has been the “gold standard” for celiac disease (CeD) for over 50 years. Despite today’s availability of sensitive and specific serological tests, the histopathological features from mucosal biopsy play a key role in diagnosing when CeD is suspected. Such a diagnostic approach requires a multidisciplinary team to optimize both tissue sampling and interpretation via the interaction between the pathologist and the gastroenterologist. Pathologists of the Italian Group of Gastrointestinal Pathology (GIPAD-SIAPEC), together with a member (TR) of the Italian Society of Technicians (AITIC) and an expert gastroenterologist (CC), provide position statements as a practical tool for reading and interpreting the report.

Moreover, a position statement was formulated about the recently described condition known as Non-Celiac Gluten Sensitivity (NCGS). Within such a diagnostic setting, both the architectural abnormalities of the duodenal mucosa, namely glandular hyperplasia, and villous atrophy and the number of intraepithelial T-lymphocytes should be well highlighted. Ancillary tests such as anti-CD3 stain are useful for an accurate count of the intraepithelial T lymphocytes when CeD or NCGS is suspected. Moreover, anti-CD3 and anti-CD8 stains are recommended in patients not responding to the gluten-free diet (GFD) to confirm a diagnosis of Refractory Celiac Disease (RCeD). Diagnostic clues about the differential diagnosis of both CeD and RCeD have also been rendered.

Somatic Mutations and Autoimmunity

Autoimmune diseases are among the most common chronic illness caused by a dysregulated immune response against self-antigens. Close to 5% of the general population in Western countries develops some form of autoimmunity, yet its underlying causes, although intensively studied, are still not fully known, and no curative therapies exist. It is well established that autoimmune diseases have common mechanisms and are caused by both genetic and non-genetic risk factors. One novel risk factor that can contribute to autoimmunity is somatic mutations, in a role parallel to their role in cancer. Somatic mutations are stochastic, de novo, non-inherited mutations. In this hypothesis, the persistent proliferation of self-reactive lymphocytes (that is usually hindered by a series of checkpoints) is permitted, due to somatic mutations in these expanding cells, allowing them to bypass multiple regulatory checkpoints, causing autoimmunity. This novel concept of the contribution of these mutations in non-malignant diseases has recently started to be explored. It proposes a novel paradigm for autoimmunity etiology and could be the missing piece of the autoimmunity puzzle.

Modern understanding of adult celiac disease

The article presents a modern view of celiac disease within the framework of the classification concept of gluten- associated disorders. The prevalence of the disease, the modern model of the etiopathogenesis of celiac disease, clinical manifestations, and the possibilities of differential diagnosis are discussed. According to the European guidelines, a strategy for monitoring outpatients with celiac disease is presented, based on baseline characteristics of the disease, regular doctor- patient interaction, and prevention of gluten- associated disorders.

Understanding Immune Thrombocytopenia: Looking Out of the Box

The pathogenesis of immune thrombocytopenia (ITP) is increasingly being elucidated, and its etiology is becoming more frequently identified, leading to a diagnostic shift from primary to secondary ITP. The overlap between autoimmunity, immunodeficiency, and cancer is evident, implying more interdisciplinarity in daily care. This mini-review is based on an expert meeting on ITP organized by the Intercontinental Cooperative ITP Study Group and presents the challenges of hematologists in understanding and investigating “out of the box” concepts associated with ITP.

Interplay Between Gluten, HLA, Innate and Adaptive Immunity Orchestrates the Development of Coeliac Disease

Several environmental, genetic, and immune factors create a "perfect storm" for the development of coeliac disease: the antigen gluten, the strong association of coeliac disease with HLA, the deamidation of gluten peptides by the enzyme transglutaminase 2 (TG2) generating peptides that bind strongly to the predisposing HLA-DQ2 or HLA-DQ8 molecules, and the ensuing unrestrained T cell response. T cell immunity is at the center of the disease contributing to the inflammatory process through the loss of tolerance to gluten and the differentiation of HLA-DQ2 or HLA-DQ8-restricted anti-gluten inflammatory CD4⁺ T cells secreting pro-inflammatory cytokines and to the killing of intestinal epithelial cells by cytotoxic intraepithelial CD8⁺ lymphocytes. However, recent studies emphasize that the individual contribution of each of these cell subsets is not sufficient and that interactions between these different populations of T cells and the simultaneous activation of innate and adaptive immune pathways in distinct gut compartments are required to promote disease immunopathology. In this review, we will discuss how tissue destruction in the context of coeliac disease results from the complex interactions between gluten, HLA molecules, TG2, and multiple innate and adaptive immune components.

Celiac Disease and Obesity: Is Bariatric Surgery an Option?

Celiac disease is an immune-mediated enteropathy associated with malabsorptive syndrome and fat-soluble vitamin deficiencies. Celiac disease affects 1% of individuals but is largely underdiagnosed, as its multifaceted clinical presentations create challenging diagnostic scenarios. With the rise of the obesity epidemic, doctors are increasingly seeing celiac disease patients with overweight or obesity, which raises the question of bariatric surgery. However, few studies so far have investigated bariatric surgery in this patient population. Here, we provide a comprehensive review of the literature on celiac disease, its nutritional consequences and complications, and we discuss the possible impact of bariatric surgery on weight loss, nutritional deficiencies, response to gluten-free diet, and long-term post-operative complications. We also review the effect of bariatric surgery on the incidence of celiac disease.

Small and Large Intestine (I): Malabsorption of Nutrients

Numerous disorders can alter the physiological mechanisms that guarantee proper digestion and absorption of nutrients (macro- and micronutrients), leading to a wide variety of symptoms and nutritional consequences. Malabsorption can be caused by many diseases of the small intestine, as well as by diseases of the pancreas, liver, biliary tract, and stomach. This article provides an overview of pathophysiologic mechanisms that lead to symptoms or complications of maldigestion (defined as the defective intraluminal hydrolysis of nutrients) or malabsorption (defined as defective mucosal absorption), as well as its clinical consequences, including both gastrointestinal symptoms and extraintestinal manifestations and/or laboratory abnormalities. The normal uptake of nutrients, vitamins, and minerals by the gastrointestinal tract (GI) requires several steps, each of which can be compromised in disease. This article will first describe the mechanisms that lead to poor assimilation of nutrients, and secondly discuss the symptoms and nutritional consequences of each specific disorder. The clinician must be aware that many malabsorptive disorders are manifested by subtle disorders, even without gastrointestinal symptoms (for example, anemia, osteoporosis, or infertility in celiac disease), so the index of suspicion must be high to recognize the underlying diseases in time.

Small bowel capsule endoscopy in refractory celiac disease: a luxury or a necessity?

Background

Small bowel capsule endoscopy (SBCE) has an established role in the management of refractory celiac disease (RCD) for the detection of complications. The aim of this study was to define the role of SBCE in the management of patients with RCD.

Method

Patients with histologically confirmed RCD who underwent successive SBCEs were recruited retrospectively from 2 tertiary centers.

Results

Sixty patients with RCD were included. The percentage extent of the affected small bowel (SB) mucosa improved on repeating a second SBCE in 26 patients (49.1%) (median 27.6% vs. 18.1%, P=0.007). Patients with RCD type II had more extensive disease than those with RCD type I on first (41.4% vs. 19.2%, P=0.004) and second (29.8% vs. 12.0%, P=0.016) SBCE. Patients with RCD type I tended to show a greater improvement in percentage of abnormal SB involved on repeat SBCE compared to those with RCD type II (P=0.049). Nine patients (15%) had RCD-related complications. Five patients developed ulcerative jejunoileitis, 3 patients developed enteropathy-associated T-cell lymphoma, and 1 patient developed cutaneous T-cell lymphoma.

Conclusions

SBCE can be a useful tool for monitoring the effects of treatment, primarily following its initiation. Patients with RCD type II have more extensive SB disease, equating to a more aggressive disease pattern.

Immune-mediated enteropathies: From bench to bedside

Immune-mediated enteropathies are caused by excessive reactions of the intestinal immune system towards non-pathogenic molecules. Enteropathy leads to malabsorption-related symptoms and include (severe) chronic diarrhea, weight loss and vitamin deficiencies. Parenteral feeding and immunosuppressive therapy are needed in severe cases. Celiac disease has long been recognized as the most common immune-mediated enteropathy in adults, but the spectrum of immune-mediated enteropathies has been expanding. Histological and clinical features are sometimes shared among these enteropathies, and therefore it may be challenging to differentiate between them. Here, we provide an overview of immune-mediated enteropathies focused on clinical presentation, establishing diagnosis, immunopathogenesis, and treatment options.

Cellular and molecular bases of refractory celiac disease

Refractory celiac disease (RCD) encompasses biologically heterogeneous disorders that develop in a small proportion (0.3%) of individuals with celiac disease that are associated with high morbidity. Two broad categories are currently recognized, type I (RCD I) and type II (RCD II), based on immunophenotypic and molecular features of the intraepithelial lymphocytes (IELs). RCD I is characterized by a polyclonal expansion of IELs displaying a normal immunophenotype, while RCD II represents a clonal proliferation of immunophenotypically "aberrant" IELs, and is considered a low-grade lymphoproliferative disorder. The pathogenesis of RCD I has not been clarified, but limited studies suggest multifactorial etiology. On the other hand, recent immunologic, molecular and immunophenotypic analyses have proposed lineage-negative innate IELs to be the cell of origin of a proportion of RCD II cases. Furthermore, sequencing studies have identified frequent, recurrent, activating mutations in members of the JAK-STAT pathway in RCD II. This finding, in conjunction with prior in vitro experimental observations, suggests roles of deregulated cytokine signaling in disease pathogenesis. In this review, we describe current understanding of environmental, immune and genetic factors associated with the development of RCD and briefly discuss diagnostic and therapeutic considerations.

An updated overview on celiac disease: from immuno-pathogenesis and immuno-genetics to therapeutic implications

INTRODUCTION

Celiac disease (CD) is an autoimmune enteropathy triggered by ingestion of gluten. While presenting many similarities with other autoimmune diseases, celiac disease is unique in that the external trigger, gluten, and the genetic background necessary for disease development (HLA DQ2/DQ8) are well described. The prevalence of celiac disease is dramatically increasing over the years and new epidemiologic data show changes regarding age of onset and symptoms. A better understanding of CD-pathogenesis is fundamental to highlight the reasons of this rise of celiac diagnoses.

AREAS COVERED

In this review we describe CD-pathogenesis by dissecting all the components necessary to lose tolerance to gluten (ingestion of gluten, genetic predisposition, loss of barrier function and immune response). Additionally, we also highlight the role that microbiome plays in celiac disease as well as new proposed therapies and experimental tools.

EXPERT OPINION

Prevalence of autoimmune diseases is increasing around the world. As a result, modern society is strongly impacted by a social and economic burden. Given the unique characteristics of celiac disease, a better understanding of its pathogenesis and the factors that contribute to it may shed light on other autoimmune diseases for which external trigger and genetic background are not known.

Immunophenotypic Spectrum and Genomic Landscape of Refractory Celiac Disease Type II

Refractory celiac disease type II (RCD II), also referred to as "cryptic" enteropathy-associated T-cell lymphoma (EATL) or "intraepithelial T-cell lymphoma," is a rare clonal lymphoproliferative disorder that arises from innate intraepithelial lymphocytes. RCD II has a poor prognosis and frequently evolves to EATL. The pathogenesis of RCD II is not well understood and data regarding the immunophenotypic spectrum of this disease and underlying genetic alterations are limited. To gain further biological insights, we performed comprehensive immunophenotypic, targeted next-generation sequencing, and chromosome microarray analyses of 11 RCD II cases: CD4-/CD8- (n=6), CD8+ (n=4), and CD4+ (n=1), and 2 of 3 ensuing EATLs. Genetic alterations were identified in 9/11 (82%) of the RCD II cases. All 9 displayed mutations in members of the JAK-STAT signaling pathway, including frequent, recurrent STAT3 (7/9, 78%) and JAK1 (4/9, 44%) mutations, and 9/10 evaluable cases expressed phospho-STAT3. The mutated cases also harbored recurrent alterations in epigenetic regulators (TET2, n=5 and KMT2D, n=5), nuclear factor-κB (TNFAIP3, n=4), DNA damage repair (POT1, n=3), and immune evasion (CD58, n=2) pathway genes. The CD4-/CD8- and other immunophenotypic subtypes of RCD II exhibited similar molecular features. Longitudinal genetic analyses of 4 RCD II cases revealed stable mutation profiles, however, additional mutations were detected in the EATLs, which occurred at extraintestinal sites and were clonally related to antecedent RCD II. Chromosome microarray analysis demonstrated copy number changes in 3/6 RCD II cases, and 1 transformed EATL with sufficient neoplastic burden for informative analysis. Our findings provide novel information about the immunophenotypic and genomic characteristics of RCD II, elucidate early genetic events in EATL pathogenesis, and reveal potential therapeutic targets.

Ileo-colonic lymphoma: presentation, diagnosis, and management

PURPOSE OF REVIEW

The gut-associated lymphoid tissue (GALT), the bulk of which is located in the ileo-colonic region comprises the lymphoid cells of the gastrointestinal tract and confers specific immunological responses. Repetitive antigenic stimulation of these cells predispose to a monoclonal proliferation of this tissue and the eventual development of lymphoma. The gastrointestinal tract is the most commonly involved site of extranodal lymphomas. This review will focus primarily on lymphomas of the ileo-colonic region (defined as the terminal ileum, the colon, and the rectum). We will discuss the epidemiology, pathogenesis, and presentation as well as current practices in diagnosis and management.

RECENT FINDINGS

Despite the majority of the GALT to be located in the ileo-colonic region of the gut, the lymphomas in this location are relatively rare. However, the overall annual incidence of ileo-colonic lymphomas is steadily increasing. This entity has a varied spectrum of clinical presentations. Ileo-colonoscopy with adequate targeted biopsies can serve as a gold standard for definitive diagnosis. Ileo-colonic lymphomas may be managed with chemotherapy alone while surgery is reserved for highly aggressive tumors or clinical emergencies. Radiation is not a preferred adjuvant treatment for lymphomas in this location of the gut. Adequate endoscopic surveillance measures and tools to potentially prevent recurrence and improve the overall prognosis of this disease are lacking.

SUMMARY

Ileo-colonic lymphomas are rare and can present with varied symptoms and signs. Endoscopy with adequate sampling can aid in making a definitive diagnosis. Chemotherapy can be highly effective in management while surgery is indicated for emergency presentations. Adequate endoscopic surveillance tools are lacking, yet imperative to prevent recurrence and improve prognosis.

Refractory Celiac Disease Type II: A Case Report and Literature Review

We present an unusual case of 68-year-old male, who presented with acute abdomen, ulcerative jejunitis with perforation, and 2 months later with perforation of the sigmoid colon. We will also discuss difficulties in the delay in diagnosis of refractory celiac disease (RCD), specifically the atypical presentation, multiple surgeries, the consecutive failure of distinct therapeutic options, and multiple complications that occurred within the 3 months since first presentation.

Intestinal T-cell lymphoma presenting as colonic perforation in the setting of ulcerative colitis: a case report

The intestinal T-cell lymphomas are a rare group of lymphatic malignancies arising from the gastrointestinal tract. They frequently manifest with non-specific clinical and radiographic findings that may mimic several other disease processes. The most common subtype is linked with refractory coeliac disease and commonly affects the small intestine. We report a case where the diagnosis was uncovered endoscopically in a patient presenting with colonic perforation on a background of long-standing ulcerative colitis. Surgical source control was required prior to considering chemotherapy, which is the usual treatment option in lymphatic malignancies. The case highlights the importance endoscopic evaluation in inflammatory conditions of the colon.

Coeliac disease and noncoeliac wheat or gluten sensitivity

Coeliac disease (CD) and noncoeliac wheat or gluten sensitivity (NCWS/NCGS) are common gluten-related disorders. Both conditions can present with gastrointestinal and extraintestinal manifestations, which can be a challenge for physicians to discern between. Whilst coeliac serology and histological assessment are required for the diagnosis of CD, there are no clear biomarkers for the diagnosis of NCGS. The management of both conditions is with a gluten-free diet (GFD), although the duration, as well as strictness of adherence to a GFD in NCGS, is unclear. Adherence to a GFD in CD can also be challenging, with recent developments of noninvasive assessments, although histological assessment via duodenal biopsies remains the gold standard. The management of refractory coeliac disease remains particularly challenging, often requiring specialist input. Whilst wheat is noted to be a trigger for symptom generation in NCGS, it is unclear which components of wheat are responsible for symptom generation in this group, with further research required to elucidate the pathophysiology.

Non-immunological biomarkers for assessment of villous abnormalities in patients with celiac disease

BACKGROUND AND AIM

Demonstration of villous abnormalities is an essential component of diagnosis of celiac disease (CeD) that requires duodenal biopsies. There is a need for non-invasive biomarker(s) that can predict the presence of villous abnormalities.

METHODS

Levels of plasma citrulline, plasma intestinal fatty acid binding protein (I-FABP), and serum regenerating gene 1α (Reg1α) were estimated in treatment naïve patients with CeD and controls. The levels of these biomarkers and their cyclical pattern were validated in a predicted model of enteropathy. Optimum diagnostic cut-off values were derived, and the results were further validated in a prospective validation cohort.

RESULTS

While level of plasma citrulline was significantly lower, the levels of plasma I-FABP and serum Reg1α were significantly higher in patients with CeD (n = 131) in comparison with healthy (n = 216) and disease controls (n = 133), and their levels reversed after a gluten-free diet (GFD). In the model of predicted enteropathy (n = 70), a sequential decrease and then increase in the level of plasma citrulline was observed; such a sequential change was not observed with I-FABP and Reg1α. The diagnostic accuracy for prediction of presence of villous abnormality was 89% and 78% if citrulline level was  ≤ 30 μM/L and I-FABP levels were ≥ 1100 pg/mL, respectively. The results were validated in a prospective validation cohort (n = 104) with a sensitivity and specificity of 79.5% and 83.1%, respectively, for predicting villous abnormalities of modified Marsh grade > 2 at calculated cut-off values of citrulline and I-FABP.

CONCLUSIONS

Plasma citrulline  ≤ 30 μM/L is the most consistent, highly reproducible non-invasive biomarker that can predict the presence of villous abnormality and has the potential for avoiding duodenal biopsies in 78% patients suspected to have CeD.

Refractory celiac disease type II: An atypical case highlighting limitations of the current classification system

Refractory celiac disease (RCD) is a rare condition associated with high morbidity that develops in individuals with celiac disease. It is known to be biologically heterogeneous, and currently two types are recognized based on immunophenotypic and molecular features, type I (RCD I) and type II (RCD II). Differentiating between RCD I and RCD II is critical, as patients with RCD II have substantially worse outcomes and a high risk of developing enteropathy-associated T-cell lymphoma. However, the current RCD classification is limited in scope, and atypical presentations and immunophenotypes are not recognized at present. Herein, we describe a unique case of RCD II with atypical clinical (primarily neurologic manifestations and lack of significant gastrointestinal symptoms), histopathologic (no villous atrophy), immunophenotypic (virtual absence of cytoplasmic CD3 expression), and molecular features (absence of clonal TR rearrangement and identification of pathogenic STAT3 and KMT2D mutations). This case highlights limitations of the current RCD classification system and the utility of next generation sequencing (NGS) studies in the diagnostic workup of RCD. Future algorithms need to recognize extraintestinal manifestations and incorporate atypical histopathologic and immunophenotypic features, as well as results of NGS analysis for RCD II classification.

Phenotypic shift of small intestinal intra-epithelial type 1 innate lymphoid cells in celiac disease is associated with enhanced cytotoxic potential

The small intestinal (SI) epithelium harbors a heterogeneous population of lymphocytes that mediate mucosal damage and repair in celiac disease (CD). The composition and roles of human proximal SI intra-epithelial innate lymphoid cells (ILCs), and their alterations in CD, are not well understood. We report that duodenal intra-epithelial ILCs predominantly consist of natural killer (NK)p44⁺ CD127^- cytotoxic ILC1s and NKp44^- CD127⁺ helper ILC1s, while ILC3s only represent a minor population. In patients with newly diagnosed or active CD (ACD) and refractory CD type 1 (RCD I), the frequency of SI NKp44⁺ ILCs is decreased, with restoration of NKp44⁺ ILC frequency observed in patients adhering to a gluten-free diet who show evidence of mucosal healing. Moreover, the frequency of SI NKp44^- ILCs is increased in ACD and RCD I patients and correlates with the severity of villous atrophy and epithelial damage, as assessed by serum levels of fatty acid binding protein 2 (FABP2). We show that the ILC alterations in CD represent a phenotypic shift of cytotoxic ILC1s rather than an increase in helper ILC1s or transdifferentiation of ILC1s to ILC3s, and activation-induced loss of NKp44 by cytotoxic ILC1s is associated with increased interferon (IFN)-γ expression and release of lytic granules. These findings suggest that intra-epithelial NKp44^- CD127^- cytotoxic ILC1s may contribute to mucosal damage in CD.