Flat small intestinal mucosa and autoantibodies against the gut epithelium

Adult-Onset Autoimmune Enteropathy in an European Tertiary Referral Center

INTRODUCTION

Adult-onset autoimmune enteropathy (AIE) is a rare cause of severe chronic diarrhea because of small intestinal villous atrophy. We report on patients with adult-onset AIE in an European referral center.

METHODS

Retrospective study including patients diagnosed with AIE in the Amsterdam UMC, location VUmc, between January 2003 and December 2019. Clinical, serological, and histological features and response to treatment were reported. The specificity of antienterocyte antibodies (AEA) was evaluated by examining the prevalence of AEA in (i) controls (n = 30) and in patients with (ii) AIE (n = 13), (iii) celiac disease (CD, n = 52), (iv) refractory celiac disease type 2 (n = 18), and (v) enteropathy-associated T-cell lymphoma (EATL, n = 10).

RESULTS

Thirteen AIE patients were included, 8 women (62%), median age of 52 years (range 23-73), and 6 (46%) with an autoimmune disease. AEA were observed in 11 cases (85%), but were also found in CD (7.7%), refractory celiac disease type 2 (16.7%), and EATL (20%). Ten patients (77%) were human leukocyte antigen DQ2.5 heterozygous. Total parenteral nutrition was required in 8 cases (62%). Steroids induced clinical remission in 8 cases (62%). Step-up therapy with rituximab, cyclosporine, infliximab, and cladribine in steroid-refractory patients was only moderately effective. Four patients died (31%), but 4 (31%) others are in long-term drug-free remission after receiving immunosuppressive treatment, including 1 patient who underwent autologous stem cell transplantation.

DISCUSSION

Adult-onset AIE is a rare but severe enteropathy that occurs in patients susceptible for autoimmune disease. Four patients (31%) died secondary to therapy-refractory malabsorption, while immunosuppressive therapy leads to a long-lasting drug-free remission in one-third of patients.

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.

[Autoimmune enteropathy in adults : A rare and difficult but relevant differential diagnosis of chronic diarrhea]

Autoimmune enteropathy (AIE) was originally believed to be a pediatric disease until there were increasing numbers of adult cases reported over the last 20 years. AIE is an autoimmune disease that manifests as severe chronic diarrhea.The histological hallmark is villous atrophy. Histology alone is not sufficiently sensitive and consistent. Four different histological patterns are known. There are many differential diagnoses to be considered relating to both histology and symptoms.We present the case of a young woman with fatal AIE and homozygous germline-mutation of the CLEC7A gene. The course of disease is documented in multiple intestinal biopsies, which show a morphological change over time.Histology and symptoms often resemble celiac disease. In order to recognize this rare disease early in its course there is a need for a special awareness among attending physicians and pathologists.

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.

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.

Pediatric autoimmune enteropathy: an entity frequently associated with immunodeficiency disorders

The term pediatric autoimmune enteropathy was originally applied to a form of intractable diarrhea seen in children under the age of 6 months and characterized by male predominance, concurrent autoimmune-associated disorders, circulating gut autoantibodies, a lack of severe immunodeficiency and small bowel atrophy with prominent crypt apoptosis. However, recent studies have cast doubt over the specific clinicopathologic findings associated with this entity. We, therefore, collected 178 gastrointestinal biopsies from 14 patients and examined their clinical, serologic and pathologic findings. Patients at presentation ranged in age from birth to 15.9 years (median, 5.5 months; mean, 4.1 years) and included six males and eight females. All children suffered from chronic watery diarrhea and malnutrition. Concomitant-associated disorders were noted in 11 (79%) cases and included 10 (71%) with an immunodeficiency disorder and/or another autoimmune-related disease. Eleven patients (79%) were positive for anti-enterocyte antibodies. The salient findings of autoimmune enteropathy were most prominent in the small intestines and the majority (79%) of patients demonstrated villous blunting, crypt hyperplasia, mononuclear cell inflammatory expansion of the lamina propria and crypt apoptosis. The remaining (21%) patients showed marked intraepithelial lymphocytosis reminiscent of celiac disease. Further, acute cryptitis and crypt abscesses were seen in seven (50%) patients obscuring the presence of apoptosis. The absence of Paneth cells, goblet cells or both was noted in seven (50%) patients. Follow-up information was available for all patients with 13 (93%) receiving immunosuppressant therapy and demonstrating partial-to-complete response. In total, three patients died from continued diarrhea and sepsis with one decedent before treatment could be initiated. In summary, autoimmune enteropathy in children is a heterogenous disease with protean clinical and pathologic findings. Although anti-enterocyte antibodies were identified in the majority of the cases, their presence was variable and insensitive. In addition, pediatric autoimmune enteropathy was frequently encountered in the setting of immunodeficiency disorders.

Diarrheal Illness in the Pediatric Population: A Review of Neonatal Enteropathies and Childhood Idiopathic Inflammatory Bowel Disease

In the clinical context of pediatric diarrheal illness, the interpretation of endoscopic mucosal biopsies varies significantly from that in adults. This review outlines these differences by first describing a host of diarrheal illnesses that are nearly exclusive to the pediatric age group. The final portion of this article describes salient pathologic differences between adult and pediatric idiopathic inflammatory bowel disease. The goal of this review is to provide a brief description of each disease process and focus on practical aspects of diagnosis that are applicable for pathologists working in general practice settings.

Autoimmune enteropathy: a review and update of clinical management

Autoimmune enteropathy (AIE) is a rare condition characterized by intractable diarrhea, histologic changes on small intestinal biopsy, and failed response to dietary manipulation that also may present with extraintestinal manifestations. In many patients, immunosuppressive therapies are necessary. Although AIE is more common in infants, adult involvement has also been documented. Much of what is known about AIE has been gathered from case reports and small case series; therefore, more research in this evolving field is needed. IPEX (immunodysregulation polyendocrinopathy enteropathy X-linked syndrome) and APECED (autoimmune phenomena, polyendocrinopathy, candidiasis, and ectodermal dystrophy) are systemic forms of AIE.

Autoimmune enteropathy: a review and update of clinical management

Autoimmune enteropathy (AIE) is a rare condition characterized by intractable diarrhea, histologic changes on small intestinal biopsy, and failed response to dietary manipulation that also may present with extraintestinal manifestations. In many patients, immunosuppressive therapies are necessary. Although AIE is more common in infants, adult involvement has also been documented. Much of what is known about AIE has been gathered from case reports and small case series; therefore, more research in this evolving field is needed. IPEX (immunodysregulation polyendocrinopathy enteropathy X-linked syndrome) and APECED (autoimmune phenomena, polyendocrinopathy, candidiasis, and ectodermal dystrophy) are systemic forms of AIE.

Autoantibodies to villin occur frequently in IPEX, a severe immune dysregulation, syndrome caused by mutation of FOXP3

Intractable diarrhea is a major symptom of immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome and associated with autoantibodies against enterocytes. Although autoimmune enteropathy (AIE)-related 75 kDa antigen (AIE-75) is a prominent autoantigen involved in the enteropathy associated with IPEX syndrome, some patients with this syndrome demonstrated autoantibody recognizing a 95 kDa protein rather than AIE-75 in the small intestine. We, herewith, identified villin, an actin-binding protein, as the 95 kDa antigen. Four of five sera from patients with IPEX syndrome reacted with a fusion protein of glutathione-S-transferase and full length villin (GST-villin), whereas only three of 98 control sera weakly reacted with GST-villin. Anti-AIE-75 antibody was detected in all five IPEX sera but not in normal or control disease sera. We conclude that both AIE-75 and villin appear to be brush border autoantigens in IPEX syndrome and could be used for the diagnosis of AIE in patients with presumptive IPEX syndrome.

[Autoimmune enteropathy in an adult patient]

Autoimmune enteropathy (AIE) is an infrequent cause of malabsorption that is usually associated with the presence of circulating autoantibodies and a predisposition to autoimmune disorders. This disease is more frequent in children. The diagnosis of this disorder is based on five criteria: chronic diarrhea (>6 weeks), malabsorption, specific histological findings, exclusion of similar disorders, and the presence of specific antibodies such as anti-enterocyte and anti-goblet cell antibodies. We present the case of a 63-year-old patient with chronic diarrhea, weight loss and significant deterioration of nutritional status.

Autoimmune enteropathy in children and adults

Autoimmune enteropathy 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, although some cases of adult onset have been reported in the literature. Pathogenetic mechanisms involve immunological disorders, in which the presence of antienterocyte autoantibodies, although detected since first description, seems now to be secondary. As occurs frequently in autoimmunity, subjects with autoimmune enteropathy may be affected by other autoimmune disorders, sometimes leading to particular forms, i.e. the IPEX syndrome and the APECED syndrome. The prognosis of autoimmune enteropathy patients depends on the severity of digestive symptoms (including fecal output), on the severity and extension of histological lesions along the gastrointestinal apparatus, and on the presence of extra-intestinal involvement. Management of autoimmune enteropathy patients is based on nutritional support and adequate hydration to ensure optimal growth and development, together with immunosuppressive therapy. Recently, biological agents have been introduced, with apparent beneficial effects.

The role of histopathology in diagnosing protracted diarrhea of infancy

Protracted diarrhea is used to describe infants with loose and frequent stools of sufficient severity to require nutritional support, most commonly parenteral nutrition. Despite similar clinical presentations, the causes of protracted diarrhea in infants are varied and diverse in management and prognosis. The following cases represent the two more common causes of protracted diarrhea in young infants in the developed world - allergic and autoimmune enteropathy. Both patients demonstrate diagnostic challenges related to clinical and/or laboratory features. These cases illustrate the important role histological assessment plays in determining the correct diagnosis, treatment course and prognosis in infants with protracted diarrhea.

Adult autoimmune enteropathy

Recent reports have suggested that autoimmune enteropathy involving the small bowel may occur in adults as well as in children. Apparently, the endoscopic and histological changes are similar to celiac disease before treatment, but these are not altered by any form of dietary restriction, including a gluten-free diet. As in celiac disease, histologic changes in gastric and colonic biopsies have also been recorded. Anti-enterocyte antibodies detected with immunofluorescent methods have been reported by a few laboratories, but these antibodies appear not to be specific and may simply represent epiphenomena. A widely available, reproducible and quantitative anti-enterocyte antibody assay is needed that could be applied in small bowel disorders that have the histological appearance of celiac disease, but fail to respond to a gluten-free diet.

Adult autoimmune enteropathy: Mayo Clinic Rochester experience

BACKGROUND & AIMS

Autoimmune enteropathy is a rare cause of intractable diarrhea associated with circulating gut autoantibodies and a predisposition to autoimmunity. It is rarely observed in adults, with only 11 cases reported to date.

METHODS

Fifteen adults with autoimmune enteropathy were identified at the Mayo Clinic, Rochester, from May 2001-June 2006. The demographic, clinical, and treatment data were abstracted from their records.

RESULTS

The study population was 87% white, 47% female, with median age of 55 years (interquartile range, 42-67 years). All patients had protracted diarrhea, weight loss, and malnutrition. Celiac disease was excluded by lack of response to gluten-free diet or absence of the celiac disease susceptibility HLA genotypes. Fourteen patients were tested for gut epithelial cell antibodies, and 93% were positive for anti-enterocyte and/or anti-goblet cell antibodies. Predisposition to autoimmune diseases was noted in 80%, as indicated by a variety of circulating autoantibodies. Small intestinal histopathologic findings included subtotal villous atrophy and lymphoplasmacytic infiltration in the lamina propria with relatively few surface intraepithelial lymphocytes. T-cell receptor gene rearrangement studies were negative in all cases. Immunosuppressive therapy was required in 93% of cases. Clinical improvement was noted in 60% after 1-8 weeks of steroid therapy.

CONCLUSIONS

Autoimmune enteropathy is a heterogeneous disease and should be considered in the differential diagnosis of malabsorption and small bowel villous atrophy. The presence of gut epithelial cell antibodies can help confirm the diagnosis. No single agent is unequivocally effective in inducing remission, and immunosuppressive therapy is required in most cases.

Clinical and immunological features of adult-onset generalized autoimmune gut disorder

OBJECTIVES

Autoimmune enteropathy is a rare disorder of unknown pathogenesis, characterized by protracted diarrhea, villous atrophy, and enterocyte autoantibodies. Its association with extended inflammation of the whole gastrointestinal tract is termed as generalized autoimmune gut disorder (GAGD), generally a pediatric disease of difficult management due to its association with immunodeficiency. The aim of our work is to describe the mucosal immunological basis of an adult-onset case of GAGD.

METHODS

We studied an adult female with a severe inflammatory involvement of the gastrointestinal tract (stomach, small and large bowel, and liver) and antienterocyte autoantibodies. She had antibody deficiency and a predisposition to systemic autoimmunity. We analyzed, by immunohistochemistry and flow cytometry, the phenotypic and functional characteristics of her intestinal intraepithelial and lamina propria (LP) lymphocytes.

RESULTS

We observed the prominent and constant presence of an unusual CD4+alphaE/beta7- Tc subset in the jejunal epithelium. Signs of the lymphocyte activation as well as the prominent lymphoid TNF-alpha production observed in the rectal mucosa support the involvement of a cell-mediated pro-inflammatory response in the pathogenesis of GAGD.

CONCLUSIONS

We report the second case of an adult fulfilling all diagnostic criteria for GAGD. We propose that the activated LP CD4+ T lymphocytes, as well as those atypically located in the epithelium, may play a pathogenic role. The alphaE/beta7- IEL could constitute a diagnostic marker of intestinal autoimmunity in the cases when autoantibodies are not evidenced, and mucosal TNF-alpha might represent a novel therapeutic target in this severe disease.

Identification of an autoimmune enteropathy-related 75-kilodalton antigen

BACKGROUND & AIMS

We have previously reported a 75-kilodalton autoantigen specific to X-linked autoimmune enteropathy (AIE) associated with tubulonephropathy. The aim of this study was to identify the autoantigen.

METHODS

Complementary DNA (cDNA) clones were isolated by immunoscreening a human duodenal cDNA-expression library with serum from a patient with AIE.

RESULTS

cDNA encoding the 75-kilodalton antigen (AIE-75) was identified. The composite nucleotide sequence of the cDNA for AIE-75 was 2214 base pairs long and encoded 552 amino acids. The genomic sequence of AIE-75 was found in Sequence DataBank, which consisted of 21 exons and was located on the chromosome 11p14.3. Recombinant AIE-75 specifically reacted with sera from 3 of 4 unrelated patients with AIE but not with 58 control sera. AIE-75 was predominantly distributed in the epithelial cells of the luminal surface and the upper half of the crypts of the intestine and in the proximal renal tubulus. Similarity searches revealed that the AIE-75 cDNA sequence was an authentic form of several colon cancer-related cDNAs of unknown function. The deduced amino acid sequence contained 3 conserved PSD-95/Dlg/ZO-1 (PDZ) domains.

CONCLUSIONS

AIE-75 is a PDZ domain-containing protein expressed in the differentiated epithelial cells of the intestine and kidney and may be involved in protein-protein interaction. The identification of the autoantigen may prove useful in the approach to the pathogenesis of this poorly understood disease.

Autoimmune enteropathy with distinct mucosal features in T-cell activation deficiency: the contribution of T cells to the mucosal lesion

BACKGROUND

Autoimmune enteropathy is normally characterised by crypt hyperplastic villous atrophy with enterocyte autoantibodies, activation of mucosal lymphocytes and increased epithelial HLA-DR. This case involved a severely affected Portuguese infant who was found to have lymphocyte activation deficiency and demonstrated correspondingly distinct mucosal features.

METHODS

A female infant of nonconsanguineous parents was treated for vomiting and diarrhoea, first with milk exclusion and then with parenteral nutrition. Lymphocyte subsets and immunoglobulin concentrations were normal, but in vitro testing showed no activation in response to phytohaemagglutinin, Candida, or purified protein derivative, although the response to interleukin (IL)-2 was intact. Interleukin-2 deficiency was excluded. Analysis of jejunal biopsy specimens revealed only mild villous blunting with absent goblet cells, normal epithelial proliferation, and no crypt hyperplasia. The dense infiltrate of CD8+ and CD4+ T lymphocytes showed normal CD2 and CD3 expression but no activation or proliferation markers. HLA-DR was not increased on epithelium or lymphocytes. Thus, in addition to in vitro evidence for lymphocyte activation deficiency, the mucosal specimens showed no evidence of in situ T-cell activation.

RESULTS

After development of overwhelming septicaemia, the patient died at 18 months, just before a planned bone marrow transplant.

CONCLUSIONS

These findings confirm significant heterogeneity within autoimmune enteropathy. Formal immune function testing should be performed in all affected infants to identify T-cell activation deficiencies. The distinct mucosal findings suggest that activated T cells usually induce the crypt hyperplastic villous atrophy characteristic of classic autoimmune enteropathy.

Autoimmune enteropathy

Autoimmune enteropathy (AIE) is an entity reported primarily in infancy, resulting in intractable diarrhea and associated with small bowel villous atrophy and the presence of circulating anti-enterocyte (AEA) antibodies. It is a multisystem disorder with a response, in many cases, to immunosuppressive therapy.

Chronic diarrhea

The differential diagnosis of chronic diarrhea varies markedly with age. In infants, it is usually a problem with formula intolerance. Because there is up to a 50% crossover intolerance between milk and soy, the infant should be given an extensively hydrolyzed formula. If such intervention is delayed, he or she may develop intractable diarrhea of infancy. Most affected toddlers have either irritable colon of infancy or protracted viral enteritis with low-grade mucosal injury and are consuming hypertonic feedings. In either case, institution of a high-fat, low-carbohydrate diet that includes whole milk often results in significant improvement. Dietary lactose rarely is a problem. A likely cause of diarrhea among children and adolescents is inflammatory bowel disease. With the exception of toddlers, chronic diarrhea suggests the presence of significant organic disease.

Autoimmune enteropathy with severe atrophic gastritis and colitis in an adult: proposal of a generalized autoimmune disorder of the alimentary tract

BACKGROUND

We describe the case of an adult with autoimmune enteropathy consistent with both severe atrophic gastritis accompanying antral stenosis and colitis.

METHODS AND RESULTS

The patient, positive for anti-intrinsic factor antibody, had intractable diarrhea and protein-losing enteropathy. In the ileum inflammatory cells were observed infiltrating the lamina propria along with villus atrophy, and similar inflammation was also found in the lamina propria of the colon and stomach, with complete loss of specialized glands. The myenteric ganglion cells of the hypertrophied muscularis propria in the stenosed antrum showed degeneration with surrounding T-lymphocyte infiltration. There were more CD8+ than CD4 lymphocytes in the lamina propria of the stomach and colon.

CONCLUSIONS

The CD8+ (suppressor-cytotoxic) T lymphocytes may have played an important role in the production of lesions in the stomach, small intestine, and colon, so we propose this case as an example of a generalized autoimmune disorder of the alimentary tract.

Syndrome of intractable diarrhoea with persistent villous atrophy in early childhood: a clinicopathological survey of 47 cases

BACKGROUND

The syndrome of intractable diarrhoea of infancy is heterogeneous and includes several diseases with diverse aetiologies. This study determines whether diagnostic categories can be defined on the basis of clinicopathological analysis.

METHODS

European Society of Paediatric Gastroenterology, Hepatology and Nutrition members were surveyed to identify cases of intractable diarrhoea with persisting small intestinal enteropathy. A retrospective clinicopathological analysis was performed on cases showing life-threatening diarrhoea within the first 24 mo of life and requiring total parenteral nutrition, which were characterized by persistent villous atrophy, and resistance to therapy.

RESULTS

Forty-seven infants were identified with intractable diarrhoea. Villous atrophy was of varying degrees with (group I, n = 24) or without (group II, n = 18) lamina propria mononuclear cell infiltration. Group I presented later, had gut autoantibodies, and a higher prevalence of protein-losing enteropathy; a subset (group Ia, n = 12) also had extraintestinal symptoms of autoimmunity associated with a later onset of larger volume diarrhoea. Group II presented early; 8 cases (group IIa) had phenotypic abnormalities and a low birth weight; the remaining 10 (group IIb) showed mild-to-moderate villous atrophy, epithelial tufting, and abnormal crypts. Group III included five patients in whom no specific features were recognised. Twenty-one (45%) died at a median age of 24 months, 20 (43%) remained dependent on parenteral (n = 16) or enteral tube (n = 4) feeding, 4 (9%) received elimination diets plus other therapies, and 2 (4%) were lost to follow-up.

CONCLUSIONS

Clinicopathological analysis allowed distinct disease groups to be identified, allowing a provisional classification to be made. This straightforward approach forms a basis for future research in this exceptionally difficult paediatric condition.

The molecular basis of intractable diarrhoea of infancy

The intractable diarrhoeas of infancy present very major problems of clinical management. However, the conceptual importance of these conditions lies in the information that they may provide about normal small-intestinal function in humans: among such infants will be found the human equivalents of the 'knock-out' mice, in which targeted gene disruption allows sometimes unexpected insight into the regulation of intestinal function. The challenge posed by the intractable diarrhoeal syndromes, of working backwards from an apparently common phenotype to probably multiple genotypes, is, however, immense. Very few of these conditions have been described at the genetic level, although the molecular basis of pathogenesis has been better explored in recent years. The two major groups of intractable diarrhoea are due to (1) primary epithelial abnormalities (which usually present within the first few days of life) and (2) immunologically mediated (which generally present after the first few weeks). The high prevalence of autoimmune enteropathy among infantile autoimmune disease, in contrast to adult autoimmunity, is intriguing and may reflect constitutive abnormality of extrathymic lymphocyte maturation. The use of potent immunosuppressive drugs and increasing expertise with parenteral nutrition are improving the outlook of these previously fatal conditions. Viewed globally, however, the pressing problem is to treat effectively the millions of infants who die from severe persistent diarrhoea and wasting, which would certainly not be considered intractable in wealthy countries.

[Autoimmune enteropathy]

Autoimmune enteropathy was initially described in young male infants presenting as severe secretory diarrhea. The disease is characterized by an inflammatory reaction which may involve several organs (bowel, pancreas, thyroid, kidneys, liver) with the presence of various circulating antibodies. The disease may also be observed in older children and in females with usually less bowel involvement. In view of the autoimmune basis of the disease, treatment requires immunosuppressive agents in addition to parenteral nutrition.

Autoimmune enteropathy with anti-goblet cell antibodies

A 9-year-old boy with a 5-year history of severe protracted diarrhea requiring home parenteral nutrition and a 1 year history of abnormal liver function tests was admitted for duodenal, rectal, and liver biopsy. Duodenal biopsy results showed mild villus blunting, a mild lymphocytic infiltrate, and absent goblet cells. Paneth cells and endocrine cells could not be identified. Review of several previous biopsies showed an almost total absence of goblet cells by light microscopy. Anti-goblet cell antibodies of the immunoglobulin (Ig)G class were shown by immunofluorescence with a titer of 1:512. Histological examination of rectal mucosa also showed a total lack of goblet cells, orderly surface epithelial cells, and infiltration of the colonic crypts by lymphocytes. Immunoperoxidase staining of rectal mucosa showed increased numbers of lymphocytes with an excess of CD3+, CD45RO+ T cells, and increased numbers of B cells labeling with B1 and L26. Increased numbers of CD25+ (activated) lymphocytes were also observed. HLA/DR expression was striking and observed in both the crypt and surface enterocytes, as well as in the lamina propria. Immunological assessment of the patient showed an inverted CD4/CD8 ratio and IgA/IgG4 deficiency. The liver biopsy and radiological investigation were in keeping with chronic sclerosing cholangitis. Although a slight and transient improvement in histological appearances was observed with prednisolone there was no significant improvement of diarrhea. Trials of azothiaprine and oral cyclosporin did not result in clinical or histological improvement.

Intractable diarrhoea in infancy: a continuing challenge for the paediatric gastroenterologist

Intractable diarrhoea of infancy is a syndrome of severe chronic diarrhoea, associated with malnutrition, which is not easily resolved by conventional management. Application of small bowel biopsy and colonoscopy with biopsy to children with this syndrome has identified specific entities, such as autoimmune enteropathy and microvillus atrophy. There remains a group of children with unexplained small intestinal enteropathy and idiopathic enterocolitis who pose a considerable problem for diagnosis and management.

Response to autoimmune enteropathy to cyclosporin A therapy

Small bowel enteropathies that are associated with an autoimmune process are often resistant to treatment. Two children with autoimmune enteropathy were treated with cyclosporin A for eight months. Both improved, as assessed by growth, small intestinal mucosal morphology, and carbohydrate absorption. Cyclosporin A is useful in the treatment of autoimmune enteropathy. This report also suggests that T cell activation (which is suppressed by cyclosporin A) is important in the pathogenesis of this condition.

Autoimmune enteropathy and nephropathy with circulating anti-epithelial cell antibodies

We describe a child with circulating anti-epithelial cell antibodies, autoimmune enteropathy with intestinal villous atrophy, and membranous glomerulonephritis. The patient had persistent diarrhea at 6 months of age, and a small bowel biopsy showed active enteritis, villous atrophy, and crypt hyperplasia. When the patient was, 10 months of age, nephrotic syndrome developed because of membranous glomerulonephritis. Results of tests for circulating immune complexes were negative. Indirect immunofluorescence studies revealed a circulating antibody directed against renal epithelial cells. Circulating antibodies directed against normal small intestine epithelial cells were also detected by the immunoperoxidase technique. Western blot and immunoprecipitation identified a 55-kd antigen, in both small bowel and kidney, that reacted with an antibody in the patient's serum. High-dose prednisone therapy induced a clinical remission, resolution of the small bowel injury, and diminished serum anti-epithelial cell antibodies; after dose reduction, clinical relapse occurred with villous atrophy and reappearance of anti-epithelial cell antibodies. When the patient was 45 months of age, persistent diarrhea recurred despite intravenous administration of corticosteroids, cyclosporine, and total parenteral nutrition. Autoantibodies to a 55-kd epithelial cell protein are temporally related to the development of enteropathy and nephropathy. Study of similar patients is needed to determine the role of such antibodies in this disorder.

Classification of intractable diarrhea in infancy using clinical and immunohistological criteria

Several experimental studies have demonstrated that activated intestinal T cells can induce villous atrophy. This observation led us to examine the possible role of activated T cells in the pathogenesis of intestinal lesions in a group of 13 children with intractable diarrhea and villous atrophy of unknown origin. Immunohistochemical study showed signs of intestinal mononuclear cell activation in seven patients. These signs included a marked increase in the number of mucosal T cells, mainly TCR alpha beta+, the appearance of lamina propria interleukin-2-receptor-bearing cells, and an increased expression of HLA-DR antigens by enterocytes. No local cause of intestinal T-cell activation was found. However, four out of seven patients had extradigestive symptoms of autoimmunity, suggesting that the intestine might also be the site of an autoimmune reaction responsible for the epithelial lesions. In these patients, presence of crypt necrosis and colic extension of the lesions suggested poor prognosis. In contrast, in six other patients, no immunohistochemical evidence of mucosal T-cell activation was obtained. In the latter cases, analysis of clinical data favored the hypothesis of a primary inborn defect of enterocyte differentiation.

Histological abnormalities in biopsies from macroscopically normal colonoscopies

One hundred and nineteen children with gastrointestinal symptoms underwent colonoscopy during the course of one year. Out of 39 children that were reported as yielding normal results on endoscopic examination, six had disease detectable only by histology. The pathology included cases of microscopic colitis, Crohn's disease, and indeterminate colitis. To exclude large bowel inflammation as a cause of gastrointestinal symptoms biopsy specimens should always be taken at endoscopy.

Autoantibodies to gliadin-binding 90 kDa glycoprotein in coeliac disease

Patients with untreated coeliac disease were found to have high concentrations of circulating antibodies to 90 kDa glycoprotein, a mannose rich protein found in skin and intestinal mucosa. In contrast, patients with active Crohn's disease or ulcerative colitis had antibody concentrations within the normal range. In coeliac disease the antibody concentrations fell significantly after gluten withdrawal. 90 kDa glycoprotein bound gliadin in a carbohydrate and calcium dependent manner. The results show that circulating antibodies directed against a gliadin-binding antigen are present in coeliac disease. 90 kDa glycoprotein may be a receptor for gliadin; in susceptible subjects ligand receptor interaction may result in cytotoxicity and antibody formation.