Congenital diabetes mellitus and fatal secretory diarrhea in two infants

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.

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.

Severe food allergy as a variant of IPEX syndrome caused by a deletion in a noncoding region of the FOXP3 gene

BACKGROUND & AIMS

Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX; OMIM 304930) syndrome is a congenital syndrome characterized by autoimmune enteropathy, endocrinopathy, dermatitis, and other autoimmune phenomena. In the present work, we aimed to uncover the molecular basis of a distinct form of IPEX syndrome presenting at the edge of autoimmunity and severe allergy.

METHODS

The FOXP3 gene was sequenced, FOXP3 messenger RNA (mRNA) was quantified by real-time polymerase chain reaction (PCR), and protein expression in peripheral blood lymphocytes was analyzed by flow cytometry after intracellular staining. In coculture experiments (CD4(+)CD25(-) and CD4(+)CD25(+) cells), the functions of regulatory T cells were analyzed. Expression of interferon gamma and interleukin 2 and 4 mRNA within the inflamed intestinal mucosa was quantified by real-time PCR.

RESULTS

Here, we describe a distinct familial form of IPEX syndrome that combines autoimmune and allergic manifestations including severe enteropathy, food allergies, atopic dermatitis, hyper-IgE, and eosinophilia. We have identified a 1388-base pair deletion (g.del-6247_-4859) of the FOXP3 gene encompassing a portion of an upstream noncoding exon (exon -1) and the adjacent intron (intron -1). This deletion impairs mRNA splicing, resulting in accumulation of unspliced pre-mRNA and alternatively spliced mRNA. This causes low FOXP3 mRNA levels and markedly decreased protein expression in peripheral blood lymphocytes of affected patients. Numbers of CD4(+)CD25(+)FOXP3(+) regulatory T cells are extremely low, and the CD4(+)CD25(+) T cells that are present exhibit little regulatory function.

CONCLUSIONS

A new mutation within an upstream noncoding region of FOXP3 results in a variant of IPEX syndrome associating autoimmune and severe immunoallergic symptoms.

Immunodeficiencies with Autoimmune Consequences

Far from being mutually exclusive, immunodeficiency and autoimmunity may occur simultaneously. During the last years, analysis of Autoimmune Polyendocrinopathy--Candidiasis--Ectodermal Dystrophy (APECED) and Immunodysregulation--Polyendocrinopathy--Enteropathy--X-linked (IPEX), two rare monogenic forms of immunodeficiency associated with autoimmunity, has led to the identification of Auto Immune Regulator (AIRE) and Forkhead Box P3 (FOXP3), essential transcriptional regulators, involved in central tolerance and peripheral immune homeostasis, respectively. Characterization of the molecular and cellular mechanisms involved in APECED, and recognition that AIRE expression is sustained by effective thymopoiesis, has recently allowed to define that the autoimmunity of Omenn syndrome, a combined immunodeficiency due to defects of V(D)J recombination, also results from defective expression of AIRE. The implications of identification of the basis of autoimmunity in these rare forms of immunodeficiency have important implications for a better understanding of more common autoimmune disorders, and for development of novel therapeutic approaches.

FOXP3 acts as a rheostat of the immune response

The study of a rare human X-linked disease resulting in a characteristic clinical phenotype of multiple autoimmune disorders and the in-depth exploration of a spontaneous mouse model, scurfy (sf), have contributed to a better understanding of the regulation of immunologic responses, particularly to self. Forkhead box P3 (FOXP3), the gene responsible for IPEX (immune dysregulation, polyendocrinopathy, enteropathy, X-linked) and sf is located on the X chromosome and is of crucial importance for the generation of CD4+ CD25+ regulatory T cells. Loss of FOXP3 function and the resultant lack of regulatory T cells result in lethal auto-aggressive lymphoproliferation, whereas overexpression of this modulator results in severe immunodeficiency. The in-depth analysis of FOXP3 regulation and elucidation of the precise mechanisms by which FOXP3 exerts its regulatory effect will provide important insights into the understanding of autoimmunity and should predictably result in new therapeutic possibilities.

Autoimmune enteropathy: molecular concepts

PURPOSE OF REVIEW

Enteropathies causing temporary or permanent intestinal failure are a big diagnostic and therapeutic challenge for pediatric gastroenterologists. A now well-recognized and distinct entity is in the form of "autoimmune enteropathy (AIE)". Recent advances in the molecular workup of AIE gave first insight into the pathophysiology of AIE. In this review, we discuss new molecular concepts of AIE resulting in new diagnostic and therapeutic possibilities.

RECENT FINDINGS

The identification of disease-causing mutations in the FOXP3 gene as a basic defect resulting in AIE points to a defect in regulatory T-cell homeostasis. FOXP3, primarily expressed by CD4+CD25+regulatory T cells, is a potent transcriptional suppressor and key modulator of T-cell functions. Nonfunctional FOXP3 leads to a tremendous hyperactivation of T cells, resulting in autoimmune aggression, such as seen in patients with immune dysregulation, polyendocrinopathy autoimmune enteropathy X-linked (IPEX) syndrome, a subgroup of AIE. There is recent evidence suggesting that a defect of regulatory factors other than FOXP3 might cause AIE. Anti-enterocyte autoantibodies, another main characteristic of AIE, seem to be of a secondary nature and can no more be considered as directly disease causing.

SUMMARY

Based on the profound immune dysregulation, new treatment strategies emerged for AIE. The use of T-cell immunosuppressive drugs, such as tacrolimus combined to steroids, seems to be beneficial in some patients; however, long-term remission is not always possible. Bone marrow transplantation might be the treatment of choice in those patients who do not respond to immunosuppression; however, the first encouraging results remain to be confirmed since to date long-term outcome remains mixed.

Immune dysregulation, polyendocrinopathy, enteropathy, and X-linked inheritance (IPEX), a syndrome of systemic autoimmunity caused by mutations of FOXP3, a critical regulator of T-cell homeostasis

Immune dysregulation, polyendocrinopathy, enteropathy, and X-linked inheritance (IPEX) is one of a group of clinical syndromes that present with multisystem autoimmune disease suggesting a phenotype of immune dysregulation. Clinically, IPEX manifests most commonly with diarrhea, insulin-dependent diabetes mellitus, thyroid disorders, and eczema. FOXP3, the gene responsible for IPEX, maps to chromosome Xp11.23-Xq13.3 and encodes a putative DNA-binding protein of the forkhead family. Recent data indicate that FOXP3 is expressed primarily in the CD4+CD25+ regulatory T-cell subset, where it may function as a transcriptional repressor and key modulator of regulatory T-cell fate and function. This review describes the clinical features of IPEX and the structure, function, and known mutations of FOXP3 that provide important insights into its role in maintenance of immune homeostasis.

Immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome: a model of immune dysregulation

PURPOSE OF REVIEW

Immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome is a fatal syndrome of overwhelming autoimmunity. Recent identification of FOXP3 as the causative gene and realization that this same gene defect occurs in the mutant mouse Scurfy has yielded new insights and hopes of unraveling the mechanism of autoimmunity in this and possibly other diseases. In this review, we describe the clinical features of immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome/Scurfy and compare this phenotype with similar syndromes caused by other single gene mutations. We examine therapeutic options to treat the syndrome, study its immunologic basis, and investigate the structure and function of the FOXP3 protein.

RECENT FINDINGS

The Scurfy mutant mouse has a characteristic phenotype that causes death by approximately 3 weeks of age. It is known that the effector cells in the Scurfy mouse are CD4+ T cells and that a population of normal T cells can control the overwhelming autoimmunity that they induce. Recent data have demonstrated that this process requires antigenic stimulation and that the degree to which the immune system responds is inversely proportional to the level of FOXP3 protein (Forkhead box P3) expression in peripheral T cells. Suppression of immune activation by FOXP3 may occur due to its ability to bind to DNA through a putative forkhead DNA-binding motif and to repress transcriptional activation from certain promoters in T cells.

SUMMARY

Because of the dramatic phenotype and rapidity of onset, immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome and Scurfy provide a powerful model in which to study mechanisms of T cell regulation. A more complete understanding of this syndrome will provide important insights into mechanisms of immune suppression, tolerance, and autoimmunity.

Clinical and molecular features of the immunodysregulation, polyendocrinopathy, enteropathy, X linked (IPEX) syndrome

Immunodysregulation, polyendocrinopathy, enteropathy, X linked (IPEX, OMIM 304790) is a rare, recessive disorder resulting in aggressive autoimmunity and early death. Mutations in FOXP3 have been identified in 13 of 14 patients tested. Research in the mouse model, scurfy, suggests that autoimmunity may stem from a lack of working regulatory T cells. We review published reports regarding the genetics, clinical features, immunology, pathology, and treatment of IPEX. We also report three new patients who were treated with long term immunosuppression, followed by bone marrow transplantation in two. IPEX can be differentiated from other genetic immune disorders by its genetics, clinical presentation, characteristic pattern of pathology, and, except for high IgE, absence of substantial laboratory evidence of immunodeficiency. While chronic treatment with immunosuppressive drugs may provide temporary benefit for some patients, it does not cause complete remission. Remission has been observed with bone marrow transplantation despite incomplete engraftment, but the long term outcome is uncertain.

IPEX is a unique X-linked syndrome characterized by immune dysfunction, polyendocrinopathy, enteropathy, and a variety of autoimmune phenomena

The rare syndrome known as IPEX (OMIM: 304930) is characterized by immune-dysfunction, polyendocrinopathy, enteropathy, and X-linked inheritance. The gene responsible for IPEX maps to Xp11.23-q13.3, a region of the X chromosome that also harbors the Wiskott-Aldrich syndrome gene ( WASP ). IPEX syndrome results from mutations of a unique DNA binding protein gene, FOXP3. Mutations invariably impair the seemingly essential forkhead domain of the protein, which is uniquely located in the carboxyl terminus, affecting protein function. In this review, we describe the identification of IPEX as a unique X-linked syndrome, the clinical features of IPEX, mutations of the immune-specific FOXP3 DNA binding protein, and bone marrow transplantation as a potential cure for the syndrome, which is usually lethal within the first year of life in affected males.

Neonatal diabetes mellitus, enteropathy, thrombocytopenia, and endocrinopathy: Further evidence for an X-linked lethal syndrome

We describe an unusual family with a fatal genetic syndrome of neonatal diabetes mellitus (DM), enteropathy, endocrinopathy, and severe infections with variable thrombocytopenia. All affected individuals are male; X-linked inheritance is likely. The most common clinical features are neonatal DM, inanition, and enteropathy; a variety of other autoimmune phenomena are less frequent. Clinical variability within and among families is common, including lack of one or more cardinal features. The syndrome is usually fatal, but survival is sometimes possible with immunosuppressive therapy. Clinical variability and frequent new mutations may contribute to poor recognition and underreporting of similar cases.

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.

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.

Growth-promoting interaction of IGF-II with the insulin receptor during mouse embryonic development

Genetic analyses of dwarfing phenotypes resulting from targeted mutagenesis of the genes encoding the insulin-like growth factors (IGF-I and IGF-II) and their cognate type 1 IGF receptor (IGF1R) have demonstrated that this signaling system is a major determinant of mouse embryonic growth. Of the two IGF ligands, IGF-I interacts exclusively with IGF1R, whereas IGF-II recognizes an additional receptor (XR), because the growth retardation of embryos lacking both IGR1R and IGF-II (30% of normal birthweight) is more severe than that manifested in either class of single Igf1r or Igf2 null mutants (45 and 60% of normal, respectively). To determine whether XR is the insulin receptor (IR), we examined embryos nullizygous for both Igf1r and Insr. While the growth of embryos lacking solely IR is affected very mildly and only at the end of gestation, concomitant absence of IGF1R results in a severe growth-deficiency phenotype (30% of normal size at birth) that is first detected at Embryonic Day 13.5 and is also characterized by transient edema, curly tail, generalized organ hypoplasia, including the muscles, developmental delays in ossification, and thin epidermis. The Igf1r/Insr double nullizygotes are phenotypically indistinguishable from double mutants lacking IGF1R and IGF-II and from other double and triple mutants in which all of the IGF ligand/receptor interactions have been eliminated. Therefore, these results provide genetic evidence that the growth-promoting function of IGF-II during mouse embryogenesis is mediated in part by signaling through the insulin receptor.

[Neonatal diabetes mellitus associated with an autoimmune disease]

BACKGROUND

Insulin-dependent diabetes mellitus can be associated to an auto-immune disease. A similar association may be seen in the neonate.

CASE REPORT

A one-day-old boy was admitted for ketoacidosis due to diabetes mellitus. Investigation showed that he also suffered from an auto-immune enteropathy with several types of autoantibodies, particularly anti-enterocytes antibodies. Immunotherapy was ineffective. Multi-organ lesions developed subsequently, particularly a pulmonary disease responsible for the death at the age of 2 years.

CONCLUSION

Physiopathology of this association remains unclear and the report of further cases should help improve our knowledge.

X-linked immune dysregulation, neonatal insulin dependent diabetes, and intractable diarrhoea

Four related male infants presented with neonatal diabetes mellitus, immune dysregulation with extremely high concentrations of immunoglobulin E, and intractable diarrhoea. They were all from one family, and all of them died. As far as is known this X-linked recessive disorder has not been described before. It is suggested that this is a new immunodeficiency in which type 2 T helper responses predominate.

[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.

Transient and permanent neonatal diabetes

Neonatal diabetes, which may be transient or permanent, is rare. Most patients are full-term but small- for-date infants. Typical symptoms of diabetes mellitus occur within the first 4 weeks of life, requiring insulin therapy and very strict blood glucose monitoring. Subsequent growth and psychomotor development are usually normal. In about 33% of these patients the diabetes remains permanent; the transient cases, however, often develop permanent diabetes mellitus later in life. Exocrine pancreatic insufficiency is present in some patients. Neonatal diabetes differs from type-I diabetes in many aspects and seems to form a distinct entity of inborn pancreatic malfunction.

Neonatal diabetes mellitus associated with severe diarrhea, hyperimmunoglobulin E syndrome, and absence of islets of Langerhans

Neonatal insulin-dependent diabetes mellitus (DM) is very rare and descriptions of the pancreatic pathology in affected infants vary considerably. Death after 10 months of a male child who suffered the onset of insulin-dependent DM as a neonate, together with severe diarrhea and features of the hyperimmunoglobulin E syndrome, was found to be associated with absence of islets of Langerhans. There was no evidence of any pancreatic exocrine abnormality or other endocrinopathy. Two male relatives with insulin-dependent DM have also died as infants, and after review of the literature it is suggested that this disease process may be part of the spectrum of an X-linked syndrome of diarrhea, polyendocrinopathy, and fatal infection in infancy. Evidence is presented to support the suggestion that this syndrome is an autoimmune disorder.