Pediatric autoimmune enteropathy: an entity frequently associated with immunodeficiency disorders

Clinical characteristics and management of autoimmune enteropathy in children: case reports and literature review

BACKGROUND

Autoimmune enteropathy (AIE) defined by intractable diarrhoea and nonceliac enteropathy with villous atrophy, is a rare digestive disease. Case reports of this disease are sporadic and the clinical characteristics of AIE is seldom discussed.

PURPOSE

We evaluate the clinical, laboratory, histopathological features, response to therapy and outcome of AIE in children.

METHOD

We conducted a retrospective analysis of five children with AIE in our hospital. A comprehensive search of MEDLINE was performed using PubMed, through keywords of "autoimmune enteropathy, pediatric or children". The clinical manifestations, endoscopic results, pathological results, and medication therapy of these children were collected and the cases were divided into two groups, infants (≤ 1 year old) and children (> 1 year old).

RESULTS

Five cases treated in our department: one case took eight years to make the final diagnosis; one case was positive for anti-intestinal epithelial cell (AE) antibody; three cases showed crypt apoptosis in histopathology; and two cases showed celiac-like changes. All cases were responsive to glucocorticoid therapy in the early stage of treatment, while three cases required immunosuppressant maintenance. After reviewing the literature, we performed a statistical analysis of 50 cases with a male-to-female ratio of 31:19. Among them, 35 patients (70%) were within 1 year of age, and their clinical manifestations were mainly watery stool (43 cases, 86%), weight loss (28 cases, 56%), abdominal distension (3 cases, 6%), serum AE or anti-goblet cell (AG) antibody positivity (32 cases, 64%), other immune-related antibodies (21 cases, 42%), gene mutations (9 cases, 18%), and family history (21 cases, 42%). All the children showed different degrees of intestinal villous atrophy. Thirty-seven (74%) of the children were treated early, and their clinical symptoms were relieved. Comparing the cases between different age groups, it was found that the mortality rate of children with onset in infancy was higher (P < 0.05), and there was no difference in other autoimmune diseases, AE antibody positivity rates, and other antibodies between the two groups. In addition to survival rate between different age group (P = 0. 005), there was no difference in sex, autoantibody positivity rate, single gene mutation, or family history between the two groups (P > 0.05) through analysis of mortality and clinical remission cases.

CONCLUSION

Endoscopic examination and mucosal pathological examination should be performed to diagnose AIE in children with watery stool and weight loss who fail to be treated with diet therapy. Immunotherapy is the core of medical management of AIE and can improve prognosis. Children with a poor prognosis in infancy should be actively treated to reduce mortality rates associated with AIE.

Severe Immune-Related Enteritis after In Utero Exposure to Pembrolizumab

Immune checkpoint blockade has become standard treatment for many types of cancer. Such therapy is indicated most often in patients with advanced or metastatic disease but has been increasingly used as adjuvant therapy in those with early-stage disease. Adverse events include immune-related organ inflammation resembling autoimmune diseases. We describe a case of severe immune-related gastroenterocolitis in a 4-month-old infant who presented with intractable diarrhea and failure to thrive after in utero exposure to pembrolizumab. Known causes of the symptoms were ruled out, and the diagnosis of pembrolizumab-induced immune-related gastroenterocolitis was supported by the results of histopathological assays, immunophenotyping, and analysis of the level of antibodies against programmed cell death protein 1 (PD-1). The infant's condition was successfully treated with prednisolone and infliximab.

APECED and the place of AIRE in the puzzle of the immune network associated with autoimmunity

In the last 20 years, discoveries about the autoimmune regulator (AIRE) protein and its critical role in immune tolerance have provided fundamental insights into understanding the molecular basis of autoimmunity. This review provides a comprehensive overview of the effect of AIRE on immunological tolerance and the characteristics of autoimmune diseases in Autoimmune Polyendocrinopathy-Candidiasis-Ectodermal Dystrophy (APECED), which is caused by biallelic AIRE mutations. A better understanding of the immunological mechanisms of AIRE deficiency may enlighten immune tolerance mechanisms and new diagnostic and treatment strategies for autoimmune diseases. Considering that not all clinical features of APECED are present in a given follow-up period, the diagnosis is not easy in a patient at the first visit. Longer follow-up and a multidisciplinary approach are essential for diagnosis. It is challenging to prevent endocrine and other organ damage compared with other diseases associated with multiple autoimmunities, such as FOXP3, LRBA, and CTLA4 deficiencies. Unfortunately, no curative therapy like haematopoietic stem cell transplantation or specific immunomodulation is present that is successful in the treatment.

[Immunopathology of the small intestine]

The gastrointestinal tract is the site of exciting immunological interactions between the epithelium and the mucosa-associated lymphoid tissue, leading to the immune response to food and microbial antigens in the digestive lumen. The objective of this review is to present the main dysimmune pathologies of the digestive tract leading to an enteropathy. As examples, we describe celiac and non-celiac enteropathies to clarify a florid diagnostic framework, by identifying a spectrum of elementary lesions, which must be confronted with the clinico biological context of the patient to orient the diagnosis. The microscopic lesions observed are most often non-specific and may be encountered in several diagnostic settings. Moreover, it is a set of elementary lesions in each clinical context that will orient the diagnostic framework. Celiac disease is the main etiology of enteropathy with villous atrophy, its diagnosis is multidisciplinary and there are many differential diagnoses. We will discuss celiac disease lymphomatous complications as enteropathy associated T-cell lymphoma including refractory sprue type 2. We will then present the non-celiac enteropathies. Among these, enteropathies of unknown etiology may be associated with a primary immune deficiency that may be reflected by florid lymphoid hyperplasia of the gastrointestinal tract and/or be associated with an infectious etiology that should also be constantly sought. Finally, we will discuss of induced enteropathy by new immunomodulatory treatments.

Beyond IBD: the genetics of other early-onset diarrhoeal disorders

Diarrhoeal disorders in childhood extend beyond the inflammatory bowel diseases. Persistent and severe forms of diarrhoea can occur from birth and are associated with significant morbidity and mortality. These disorders can affect not only the gastrointestinal tract but frequently have extraintestinal manifestations, immunodeficiencies and endocrinopathies. Genomic analysis has advanced our understanding of these conditions and has revealed precision-based treatment options such as potentially curative haematopoietic stem cell transplant. Although many new mutations have been discovered, there is frequently no clear genotype-phenotype correlation. The functional effects of gene mutations can be studied in model systems such as patient-derived organoids. This allows us to further characterise these disorders and advance our understanding of the pathophysiology of the intestinal mucosa. In this review, we will provide an up to date overview of genes involved in diarrhoeal disorders of early onset, particularly focussing on the more recently described gene defects associated with protein loosing enteropathy.

ECCO Topical Review on Clinicopathological Spectrum and Differential Diagnosis of Inflammatory Bowel Disease

INTRODUCTION

Many diseases can imitate inflammatory bowel disease [IBD] clinically and pathologically. This review outlines the differential diagnosis of IBD and discusses morphological pointers and ancillary techniques that assist with the distinction between IBD and its mimics.

METHODS

European Crohn's and Colitis Organisation [ECCO] Topical Reviews are the result of an expert consensus. For this review, ECCO announced an open call to its members and formed three working groups [WGs] to study clinical aspects, pathological considerations, and the value of ancillary techniques. All WGs performed a systematic literature search.

RESULTS

Each WG produced a draft text and drew up provisional Current Practice Position [CPP] statements that highlighted the most important conclusions. Discussions and a preliminary voting round took place, with subsequent revision of CPP statements and text and a further meeting to agree on final statements.

CONCLUSIONS

Clinicians and pathologists encounter a wide variety of mimics of IBD, including infection, drug-induced disease, vascular disorders, diverticular disease, diversion proctocolitis, radiation damage, and immune disorders. Reliable distinction requires a multidisciplinary approach.

Druggable monogenic immune defects hidden in diverse medical specialties: Focus on overlap syndromes

In the last two decades two new paradigms changed our way of perceiving primary immunodeficiencies: An increasing number of immune defects are more associated with inflammatory or autoimmune features rather than with infections. Some primary immune defects are due to hyperactive pathways that can be targeted by specific inhibitors, providing innovative precision treatments that can change the natural history of diseases. In this article we review some of these “druggable” inborn errors of immunity and describe how they can be suspected and diagnosed in diverse pediatric and adult medicine specialties. Since the availability of precision treatments can dramatically impact the course of these diseases, preventing the development of organ damage, it is crucial to widen the awareness of these conditions and to provide practical hints for a prompt detection and cure.

Pediatric autoimmune disorders with gastrointestinal expressions: from bench to bedside

The gastrointestinal (GI) tract may be involved in systemic autoimmune diseases or may be the target of organ-specific autoimmunity. Autoimmune enteropathy (AIE) is a rare disorder characterized by severe and protracted diarrhea, weight loss from malabsorption and immune-mediated damage to the intestinal mucosa, generally occurring in infants and young children, only rarely in adult. The salient histopathologic features of AIE are most prominent in the small intestine: villous blunting, crypt hyperplasia, mononuclear cell inflammatory expansion of the lamina propria with intraepithelial lymphocytosis, crypt apoptosis and absence of Paneth cells, goblet cells or both. Esophagus, stomach and colon are frequently also involved. Anti-enterocyte antibodies are identified in the majority of cases, and their presence, even if variable, can help confirming the diagnosis.

The purpose of this review is to provide an overview of the latest immunological advances in AIE, as well as to offer a practical approach for histological diagnosis for 'general' pathologist.

Histopathology of non-IBD colitis practical recommendations from pathologists of IG-IBD Group

Pathologists are often called upon to diagnose colitides that differ from the two main forms of inflammatory bowel disease (IBD). These non-IBD colitides include infectious colitis, microscopic colitis, ischemic colitis, eosinophilic colitis, autoimmune enterocolitis, segmental colitis associated with diverticulosis, drug-induced colitis, radiation colitis and diversion colitis. The diagnosis of these different disease entities relies on the histopathological examination of endoscopic biopsies of the gastrointestinal tract. This paper reviews the main histomorphological characteristics of the various Non-IBD colitides.

Etiology and Management of Pediatric Intestinal Failure: Focus on the Non-Digestive Causes

Background: Intestinal failure (IF) is defined as reduction in functioning gut mass below the minimal amount necessary for adequate digestion and absorption. In most cases, IF results from intrinsic diseases of the gastrointestinal tract (digestive IF) (DIF); few cases arise from digestive vascular components, gut annexed (liver and pancreas) and extra-digestive organs or from systemic diseases (non-digestive IF) (NDIF). The present review revised etiology and treatments of DIF and NDIF, with special focus on the pathophysiological mechanisms, whereby NDIF develops. Methods: We performed a comprehensive search of published literature from January 2010 to the present by selecting the following search strings: “intestinal failure” OR “home parenteral nutrition” OR “short bowel syndrome” OR “chronic pseudo-obstruction” OR “chronic intestinal pseudo-obstruction” OR “autoimmune enteropathy” OR “long-term parenteral nutrition”. Results: We collected overall 1656 patients with well-documented etiology of IF: 1419 with DIF (86%) and 237 with NDIF (14%), 55% males and 45% females. Among DIF cases, 66% had SBS and among NDIF cases 90% had malabsorption/maldigestion. Conclusions: The improved availability of diagnostic and therapeutic tools has increased prevalence and life expectancy of rare and severe diseases responsible for IF. The present review greatly expands the spectrum of knowledge on the pathophysiological mechanisms through which the diseases not strictly affecting the intestine can cause IF. In view of the rarity of the majority of pediatric IF diseases, the development of IF Registries is strongly required; in fact, through information flow within the network, the Registries could improve IF knowledge and management.

Seronegative autoimmune enteropathy with duodenal sparing and colonic clues in an adult female

Autoimmune enteropathy (AIE) is a rare immune disorder of the gut seldom found in adults and characterized by uncontrollable diarrhea resulting in malabsorption. While AIE is known to be pan-enteric, virtually all cases have presented with altered duodenal histology following known patterns with or without macroscopic change. We describe a unique case of seronegative AIE lacking typical duodenal manifestations in a 43-year-old female. To our knowledge, this is the first report of AIE lacking usual duodenal histologic changes, which resulted in missed diagnosis for years. Ultimately, crypt epithelial apoptosis, mononuclear inflammation of the lamina propria, and goblet cell loss of intestinal mucosa besides the duodenum clinched the diagnosis of AIE. Colonic histologic abnormalities consistent with AIE in the setting of diarrhea with malnutrition despite duodenal sparing should prompt suspicion for AIE given the pan-enteric nature of this disease.

A case of autoimmune enteropathy with CTLA4 haploinsufficiency

Autoimmune enteropathy (AIE) is a rare disease, characterized by intractable diarrhea, villous atrophy of the small intestine, and the presence of circulating anti-enterocyte autoantibodies. Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome, and mutations in FOXP3, which is a master gene of regulatory T cells (Tregs), are major causes of AIE. Recent studies have demonstrated that mutations in other Treg-associated genes, such as CD25 and CTLA4, show an IPEX-like phenotype. We present the case of a 13-year-old girl with CTLA4 haploinsufficiency, suffering from recurrent immune thrombocytopenic purpura and intractable diarrhea. We detected an autoantibody to the AIE-related 75 kDa antigen (AIE-75), a hallmark of the IPEX syndrome, in her serum. She responded well to a medium dose of prednisolone and a controlled dose of 6-mercaptopurine (6-MP), even after the cessation of prednisolone administration. Serum levels of the soluble interleukin-2 receptor and immunoglobulin G (IgG) were useful in monitoring disease activity during 6-MP therapy. In conclusion, autoimmune-mediated mechanisms, similar to the IPEX syndrome, may be involved in the development of enteropathy in CTLA4 haploinsufficiency. Treatment with 6-MP and monitoring of disease activity using serum levels of soluble interleukin-2 receptor and IgG is suggested for such cases.

A Review of Autoimmune Enteropathy and Its Associated Syndromes

Autoimmune enteropathy is an extremely rare condition characterized by an abnormal intestinal immune response which typically manifests within the first 6 months of life as severe, intractable diarrhea that does not respond to dietary modification. Affected individuals frequently present with other signs of autoimmunity. The diagnosis is made based on a characteristic combination of clinical symptoms, laboratory studies, and histological features on small bowel biopsy. Autoimmune enteropathy is associated with a number of other conditions and syndromes, most notably immunodysregulation polyendocrinopathy enteropathy X-linked (IPEX) syndrome and autoimmune polyglandular syndrome type 1 (APS-1). Diagnosis and treatment is challenging, and further research is needed to better understand the pathogenesis, disease progression, and long-term outcomes of these conditions.

Neuroendocrine Cells Are Commonly Absent in the Intestinal Crypts in Autoimmune Enteropathy

The absence of neuroendocrine (NE) cells in the intestinal mucosa in autoimmune enteropathy (AIE) has been occasionally reported. However, the status of NE cells has not been studied in detail in AIE. Small bowel and colonic biopsies were retrospectively retrieved from 18 AIE patients (26 baseline [18 small bowel and 8 colon]; and 15 follow-up [11 duodenum and 4 colon] biopsies in 11 patients). Thirty-three common variable immunodeficiency (CVID) patients (30 small bowel and 16 colon), 15 inflammatory bowel disease patients (5 duodenum and 10 colon), 13 immunoglobulinA deficiency patients (13 duodenum and 5 colon), and 10 normal controls (5 colon and 5 duodenum) were selected as control groups. Histologic features (villous atrophy, intraepithelial lymphocytosis, acute inflammation, crypt apoptosis, and absence or presence of goblet cells, Paneth cells and plasma cells) were recorded. Chromogranin immunostain was performed and chromogranin-positive NE cells were counted per 10 consecutive, well-oriented crypts. On the basis of the number of chromogranin-positive NE cells, cases were graded as being absent (≤3 NE cells), markedly decreased (≤15), and intact (>15). The NE cell status correlated with histologic features. The median age of 18 AIE patients was 38.5 years (range: 11 to 74 y) and 14 patients were male. Fourteen of 18 (78%) patients showed loss (absent or markedly decreased) of NE cells in the small bowel and/or colon in the baseline biopsies including 12 (of 18) small bowel and 6 (of 8) colon biopsies. Follow-up biopsy was available in 11 patients. Six of 7 (85%) patients who showed loss of NE cells in the baseline biopsies regained NE cells in the follow-up biopsies, and 1 patient continued to show loss of NE cells. Four patients who showed intact NE cells in the baseline remained unchanged in the follow-up. Among the control groups, 3 of 33 (9%) CVID patients showed loss of NE cells. NE cells were not lost in the biopsies of all 15 and 13 patients with inflammatory bowel disease and immunoglobulinA deficiency, respectively, or the 10 normal controls. In all 41 biopsies (26 baseline plus 15 follow-up) with AIE, NE cell loss was significantly associated with increased crypt apoptosis and loss of goblet cells (P=0.001, both) but not with other histologic findings. In conclusion, our study suggests that NE cells may also be the target cells in AIE and commonly lost in the intestinal crypts in AIE, and consequently loss of NE cells can be used as an adjunct histologic feature for diagnosis of AIE.

Updates in Pediatric Congenital Enteropathies: Differential Diagnosis, Testing, and Genetics

Congenital enteropathies comprise a heterogeneous group of disorders typically resulting in severe diarrhea and intestinal failure. Recent advances in and more widespread application of genetic testing have allowed more accurate diagnosis of these entities as well as identification of new disorders, provided a deeper understanding of intestinal pathophysiology through genotype-phenotype correlations, and permitted the exploration of more specific therapies to diseases that have heretofore been resistant to conventional treatments. The therapeutic armamentarium for these disorders now includes intestinal and hematopoietic stem cell transplantation, specific targeted therapy, such as the use of interleukin-1 receptor antagonists and, in some cases, gene therapy. These considerations are particularly applicable to the group of disorders identified as "very-early onset inflammatory bowel disease" (VEO-IBD), for which a veritable explosion of knowledge has occurred in the last decade. The pathologist plays a crucial role in assisting in the diagnosis of these entities and in ruling out other disorders that enter into the differential diagnosis.

Autoimmune Gastritis in Pediatrics: A Review of 3 Cases

OBJECTIVES

To bring heightened awareness to a condition, autoimmune gastritis (AIG), which is a well-established entity in adults; however, rarely described in pediatrics. Currently, the literature describes AIG in pediatric patients who also suffer from other autoimmune disorders, which precedes the diagnosis of AIG, and often presents with unexplained anemia. Additionally, there have been case reports describing patients with immunodeficiencies and AIG, which progress to gastric adenocarcinoma. AIG is a histopathologic diagnosis, demonstrating chronic inflammatory process with loss of parietal cells with or without intestinal metaplasia and enterochromaffin-like cell hyperplasia. Management of these patients includes nutritional replacement as well as routine surveillance endoscopy with biopsy in search of metaplastic and dysplastic changes.

METHODS

We queried the pathology database at Children's Hospital Los Angeles (CHLA) for cases with a final diagnosis of AIG and for those with a differential diagnosis that includes AIG in the diagnostic comment. All cases that were identified were selected as long as they did not only meet the histopathologic criteria, but also the biochemical criteria for this condition.

RESULTS

Of the 3 patients, 2 were referred to gastroenterology for the evaluation of iron-deficiency anemia in the context of diabetes mellitus and Addison's disease; and diabetes mellitus and Hashimoto's thyroiditis. AIG was confirmed on the biopsies, which showed a reduction in parietal cell mass, pseudopyloric metaplasia and enterochromafin-like cell hyperplasia. Both patients were treated with iron replacement therapy. The third patient presented with symptomatic anemia and diagnosed with pernicious anemia without other autoimmune disorders. She was successfully treated with oral vitamin supplementation. In this case, serial gastric biopsies demonstrated stable intestinal metaplasia without evidence of dysplasia.

CONCLUSION

Although AIG is rare in children, pediatric gastroenterologists and pathologists should have a heightened suspicion for this entity in those patients with a history of autoimmune disorders and/or pernicious anemia.

Clinical manifestations and gastrointestinal pathology in 40 patients with autoimmune enteropathy

Autoimmune enteropathy (AIE) is a rare condition that may affect pediatric and adult patients, frequently associated with primary immunodeficiencies. We performed a retrospective study on clinical and histological findings from 40 AIE patients. Histological presentation showed a prevalent celiac disease pattern (50%), followed by the mixed pattern (35%), independently of age, chronic active duodenitis (10%), and GVHD-like pattern (5%). Patients with primary immunodeficiencies (24/40) presented mainly with the celiac disease pattern (72.2% versus 22.2%; p < .0001), while patients without primary immunodeficiencies presented with a mixed histological pattern (61.1% versus 13.6%; p < .0001). Our study shows that the prevalent histological presentation is the celiac disease-like pattern, independently of age, and, for the first time, that the histological presentation of AIE differs significantly between patients with and without primary immunodeficiencies. These findings may be helpful for more precise and timely diagnosis and management of this rare disorder.

Consideration of Maternal Anti-enterocyte IgA Transfer With Resulting Infantile Alloimmune Enteropathy

Autoimmune enteropathy is a rare cause of infantile diarrhea. Cases typically involve infants with a protracted course of diarrhea found to have underlying autoimmune disease or immune dysfunction, leading to chronic intestinal inflammation. We describe a case of immune-mediated enteropathy in an infant with no identifiable autoimmune disease. The patient was exclusively breastfed by his mother who had Crohn's disease, and he was found to have circulating anti-enterocyte immunoglobulin A (IgA) antibody. There was no circulating anti-enterocyte immunoglobulin G or immunoglobulin M. The patient's disease and symptoms resolved with cessation of breastfeeding, and no immunomodulatory medications have been needed in 20 months of follow-up. The case raises suspicion for alloimmune disease, and it is hypothesized that intestinal injury was mediated by maternally transmitted anti-enterocyte IgA antibody.

Autoimmune Enteropathy: An Updated Review with Special Focus on Stem Cell Transplant Therapy

Autoimmune enteropathy (AIE) is a complex disease affecting both children and adults. Although associated with significant morbidity and mortality, the pathophysiology of the disease and its treatment have not been well characterized. This study aims to review the medical literature available on this rare but clinically significant ailment, to help establish a better understanding of its pathophysiology and enumerate the available diagnostic and treatment modalities. A literature search was conducted on PubMed using key terms related to autoimmune enteropathy and intractable diarrhea, with no restrictions on the date of publication or language. We found a total of 98 reports of AIE published in the form of case reports and case series. The evidence reviewed suggests that AIE is a multifaceted disorder that requires a high index of suspicion in the appropriate clinical setting to be able to make an early diagnosis. Current evidence supports the use of supportive care to correct nutritional and metabolic deficiencies, and immunosuppressives and immunomodulators as directed therapies. Hematopoietic stem cell transplant is an aggressive, but successful curative modality for patients with AIE as part of immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome. Cumulative clinical experience with management of AIE has allowed improved outcomes in transplanted and non-transplanted AIE patients even though morbidity and mortality with are still high in patients with this condition. More research is needed to further define the role of new therapies for AIE, and a central registry with participation of multiple institutions might help share and standardize care of patients with this rare but serious condition.

Differing Performance of the Warning Signs for Immunodeficiency in the Diagnosis of Pediatric Versus Adult Patients in a Two-Center Tertiary Referral Population

PURPOSE

Primary immunodeficiency (PID) represents disorders with a spectrum of clinical presentations. The medical community seeks clinical features to prompt evaluation for immunodeficiency given improved prognosis with early identification. We hoped to identify clinical characteristics that would improve the diagnostic accuracy of the widely disseminated Jeffrey Modell Foundation warning signs for immunodeficiency.

METHODS

We performed a retrospective chart review in a two-center North American cohort of patients with PID. Charts of 137 pediatric and 400 adult patients with PID were evaluated for the presence of these warning signs and compared to controls with normal preliminary biochemical immune evaluation.

RESULTS

Fewer than 45% of adults with PID presented with ≥ 2 warning signs, while diagnostic utility was improved in the pediatric population where the warning signs were found to be 64% sensitive. The warning signs found in a significantly increased proportion compared to controls differed for pediatric PID patients (recurrent pneumonia (OR 2.9, p < 0.001), failure to thrive (OR 2.1, p < 0.001), need for IV antibiotics (OR 2.1, p < 0.001), serious bacterial infection (OR 4.8, p < 0.001), recurrent otitis media (OR 1.5, p = 0.027)), versus adult PID patients (recurrent otitis media (OR 2.9, p < 0.001), recurrent sinusitis (OR 2.1, p < 0.001), diarrhea with weight loss (OR 2.2, p < 0.001), recurrent viral infection (OR 3.3 p < 0.001)). In evaluation for additional criteria to promote identification of immunodeficiency, linear regression models showed slightly improved diagnostic accuracy of the warning signs with the addition of autoimmunity in our pediatric PID cohort (8.7% v 2.8%, p < 0.001, ROC 0.58). Adult PID patients demonstrated atopy more frequently than controls (48.0% vs 40.3%, p = 0.011), while atopy was found to have a negative association with the presence of PID in the pediatric age group (OR 0.3, p < 0.01). No improvement in diagnostic accuracy of the warning signs was found with the addition of allergic disease, autoimmunity, or malignant and benign proliferative disease in the adult cohort.

CONCLUSIONS

We demonstrate poor diagnostic performance of warning signs for immunodeficiency in patients with PID in a retrospective chart review. Divergent warning signs of statistically significant diagnostic utility were found in pediatric versus adult patients. We suggest education of physicians on differing presentations of possible immunodeficiency between age groups, and expansion of the warning signs to include non-infectious comorbidities such as autoimmunity in pediatric patients.

Essential role of IFN-γ in T cell-associated intestinal inflammation

Paneth cells contribute to small intestinal homeostasis by secreting antimicrobial peptides and constituting the intestinal stem cell (ISC) niche. Certain T cell-mediated enteropathies are characterized by extensive Paneth cell depletion coincident with mucosal destruction and dysbiosis. In this study, mechanisms of intestinal crypt injury have been investigated by characterizing responses of mouse intestinal organoids (enteroids) in coculture with mouse T lymphocytes. Activated T cells induced enteroid damage, reduced Paneth cell and Lgr5+ ISC mRNA levels, and induced Paneth cell death through a caspase-3/7-dependent mechanism. IFN-γ mediated these effects, because IFN-γ receptor-null enteroids were unaffected by activated T cells. In mice, administration of IFN-γ induced enteropathy with crypt hyperplasia, villus shortening, Paneth cell depletion, and modified ISC marker expression. IFN-γ exacerbated radiation enteritis, which was ameliorated by treatment with a selective JAK1/2 inhibitor. Thus, IFN-γ induced Paneth cell death and impaired regeneration of small intestinal epithelium in vivo, suggesting that IFN-γ may be a useful target for treating defective mucosal regeneration in enteric inflammation.

Educational Case: Immune-Related Disorders of the Bowel: Celiac Disease

The following fictional case is intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, see http://journals.sagepub.com/doi/10.1177/2374289517715040.

Celiac Disease and Other Causes of Duodenitis

CONTEXT

- Patients who receive an upper gastrointestinal endoscopic examination frequently have biopsies taken from the duodenum. Accurate interpretation of duodenal biopsies is essential for patient care. Celiac disease is a common clinical concern, but pathologists need to be aware of other conditions of the duodenum that mimic celiac disease.

OBJECTIVE

- To review the normal histologic features of duodenal mucosa and describe the clinical and histologic findings in celiac disease and its mimics, listing the differentiating features of biopsies with villous atrophy and epithelial lymphocytosis.

DATA SOURCES

- The study comprises a literature review of pertinent publications as of November 30, 2016.

CONCLUSIONS

- Celiac disease is a common cause of abnormal duodenal histology. However, many of the histologic features found in the duodenal biopsy of patients with celiac disease are also present in other conditions that affect the small bowel. Diagnostic precision may be enhanced by obtaining a careful patient history and by ancillary laboratory testing, particularly for the presence of antitissue transglutaminase antibodies.

Autoimmune enteropathies

Autoimmune enteropathy (AIE) is a rare condition characterized by intractable diarrhea and immune-mediated injury of the intestinal mucosa. As the clinical and histopathologic manifestations of this disease are highly variable, its diagnosis is challenging for both clinicians and pathologists. In fact, the term autoimmune enteropathies is likely more appropriate since the clinicopathologic manifestations are observed in association with a heterogeneous group of disorders. The pathophysiology of AIE has not been fully elucidated. It appears to result from dysregulation of intestinal immunity and particularly in children, often presents in association with immunodeficiency. The overarching histopathologic changes seen in AIE include mucosal inflammation and epithelial injury, although this can manifest in the form of different patterns. Recognition of the clinical settings and of the various histologic patterns can aid the pathologist in establishing the correct diagnosis.

Clinical usefulness of serum antibodies as biomarkers of gastrointestinal and liver diseases

The progressively growing knowledge of the pathophysiology of a number of immune-mediated gastrointestinal and liver disorders, including autoimmune atrophic gastritis, coeliac disease, autoimmune enteropathy, inflammatory bowel disease, autoimmune hepatitis, primary sclerosing cholangitis, primary biliary cholangitis and autoimmune pancreatitis, together with the improvement of their detection methods have increased the diagnostic power of serum antibodies. In some cases - coeliac disease and autoimmune atrophic gastritis - they have radically changed gastroenterologists' diagnostic ability, while in others - autoimmune hepatitis, inflammatory bowel disease and autoimmune pancreatitis - their diagnostic performance is still inadequate. Of note, serum antibody misuse in clinical practice has raised a number of controversies, which may generate confusion in the diagnostic management of the aforementioned disorders. In this review, we critically re-evaluate the usefulness of serum antibodies as biomarkers of immune-mediated gastrointestinal and liver disorders, and discuss their pitfalls and merits.

Newcomers in paediatric GI pathology: childhood enteropathies including very early onset monogenic IBD

Childhood enteropathies are a group of diseases causing severe chronic (>2-3 weeks) diarrhoea often starting in the first week of life with the potential for fatal complications for the affected infant. Early identification and accurate classification of childhood enteropathies are, therefore, crucial for making treatment decisions to prevent life-threatening complications. Childhood enteropathies are classified into four groups based on the underlying pathology: (i) conditions related to defective digestion, absorption and transport of nutrients and electrolytes; (ii) disorders related to enterocyte differentiation and polarization; (iii) defects of enteroendocrine cell differentiation; and (iv) disorders associated with defective modulation of intestinal immune response. While the intestinal mucosa is usually normal in enteropathies related to congenital transport or enzyme deficiencies, the intestinal biopsy in other disorders may reveal a wide range of abnormalities varying from normal villous architecture to villous atrophy and/or inflammation, or features specific to the underlying disorder including epithelial abnormalities, lipid vacuolization in the enterocytes, absence of plasma cells, lymphangiectasia, microorganisms, and mucosal eosinophilic or histiocytic infiltration. This review intends to provide an update on small intestinal biopsy findings in childhood enteropathies, the "newcomers", including very early onset monogenic inflammatory bowel disease (IBD), in particular, for the practicing pathologist.

The biopsy pathology of non-coeliac enteropathy

Tropical sprue (TS) is a malabsorption syndrome of presumed infectious aetiology that affects residents of (or visitors to) the tropics. The histological changes of TS are similar to those of coeliac disease, with increased intraepithelial lymphocytes being central to both. Unlike in coeliac disease, however, a completely flat small bowel biopsy is uncommon in TS. TS typically involves the terminal ileum, whereas coeliac disease does not. Small intestinal bacterial overgrowth (SIBO) has been defined as an increase in number and/or a change in the type of bacteria in the upper gut. Conditions that predispose to SIBO are largely those that decrease or interfere with small bowel motility. The mucosal histology is variable, and may include modest villous blunting accompanied by increased lamina propria and epithelial inflammation. Autoimmune enteropathy (AE) is a family of rare diseases that share common themes such as immunodeficiency states and autoantibodies. AE cases typically have marked villous atrophy similar to that in fully developed coeliac disease, but they lack the intense surface epithelial lymphocytosis. Apoptosis and lymphocyte infiltration at the base of the crypts, crypt abscesses and cryptitis are also seen. Patients with anti-goblet cell antibodies can have a lack of goblet cells, endocrine cells, and Paneth cells.

Immunodeficiency and autoimmune enterocolopathy linked to NFAT5 haploinsufficiency

The link between autoimmune diseases and primary immunodeficiency syndromes has been increasingly appreciated. Immunologic evaluation of a young man with autoimmune enterocolopathy and unexplained infections revealed evidence of immunodeficiency, including IgG subclass deficiency, impaired Ag-induced lymphocyte proliferation, reduced cytokine production by CD8(+) T lymphocytes, and decreased numbers of NK cells. Genetic evaluation identified haploinsufficiency of NFAT5, a transcription factor regulating immune cell function and cellular adaptation to hyperosmotic stress, as a possible cause of this syndrome. Inhibition or deletion of NFAT5 in normal human and murine cells recapitulated several of the immune deficits identified in the patient. These results provide evidence of a primary immunodeficiency disorder associated with organ-specific autoimmunity linked to NFAT5 deficiency.

Gastrointestinal biopsy findings of autoimmune enteropathy: a review of 25 cases

Autoimmune enteropathy (AIE) is a rare disorder characterized by severe diarrhea and small intestinal mucosal atrophy resulting from immune-mediated injury. It remains a challenging diagnosis because of its clinicopathologic variability. To better understand its histopathologic features, we describe the gastrointestinal biopsy findings of 25 patients, including children and adults. The most common finding on small intestinal biopsy (13/25 cases, 52%) was villous blunting, expansion of the lamina propria by mixed but predominantly mononuclear inflammation, and neutrophilic cryptitis with or without crypt microabscesses. In 5 cases (20%), the duodenum exhibited changes indistinguishable from celiac disease, with villous blunting and intraepithelial lymphocytosis. Increased crypt apoptosis with minimal inflammation, resembling acute graft-versus-host disease, was observed in 4 cases (16%). The remaining 3 cases (12%) exhibited a mixture of 2 or more of the above patterns. Mucosal abnormalities outside the small intestine were present in all 24 cases with available biopsies (100%), with the stomach most commonly affected (19/22 cases, 86%), followed by the colon (14/22, 64%) and esophagus (5/18, 28%). Findings in non-small intestinal sites were variable and included mixed active and chronic inflammation, chronic inflammation alone, intraepithelial lymphocytosis, and increased apoptosis resembling acute graft-versus-host disease. In summary, AIE most commonly presents as an active enteritis with villous blunting and expansion of the lamina propria by mixed inflammation. Mucosal abnormalities are frequently seen elsewhere in the gut. AIE may thus be better regarded as a pan-gastrointestinal autoimmune disorder, and biopsies from sites other than the small intestine may greatly facilitate its diagnosis.