Differential regulation of miR-146a/FAS and miR-21/FASLG axes in autoimmune lymphoproliferative syndrome due to FAS mutation (ALPS-FAS).

Most cases of autoimmune lymphoproliferative syndrome (ALPS) have an inherited genetic defect involving apoptosis-related genes of the FAS pathway. MicroRNAs (miRNAs) are a class of small non-coding regulatory RNAs playing a role in the control of gene expression. This is the first report on miRNAs in ALPS patients. We studied a mother and son carrying the same FAS cell surface death receptor (FAS) mutation, but with only the son manifesting the signs and symptoms of ALPS-FAS. The aim was to analyse, by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), the peripheral blood mononuclear cells (PBMC) relative expression of miR-146a and miR-21, including their passenger strands and respective targets (FAS and FASLG). In comparison with healthy matched control individuals, miR-21-3p was over-expressed significantly (P = 0·0313) in the son, with no significant change in the expression of miR-146a, miR-146a-3p and miR-21. In contrast, the mother had a slight under-expression of the miR-146a pair and miR-21-3p (P = 0·0625). Regarding the miRNA targets, FAS was up-regulated markedly for the mother (P = 0·0078), but down-regulated for the son (P = 0·0625), while FASLG did not have any significant alteration. Taken together, our finding clearly suggests a role of the miR-146a/FAS axis in ALPS-FAS variable expressivity in which FAS haploinsufficiency seems to be compensated only in the mother who had the miR-146a pair down-regulated. As only the son had the major clinical manifestations of ALPS-FAS, miR-21-3p should be investigated as playing a critical role in ALPS physiopathology, including the development of lymphoma.

Autoimmune Lymphoproliferative Syndrome with Red Cell Aplasia.

Autoimmune Lymphoproliferative Syndrome (ALPS) is a rare inherited disorder of abnormal lymphocyte apoptosis, leading to chronic lymphoproliferation. It presents as lymphadenopathy, hepatosplenomegaly and autoimmune phenomena. Pure red cell aplasia is characterized by normochromic normocytic anemia, reticulocytopenia, and absence of erythroblasts from a normal bone marrow. Only few lymphoproliferative disorders have been associated with erythroid aplasia. The authors are reporting a case of ALPS associated with red cell aplasia in a 7-y-old girl.

Association of severe myoclonic epilepsy of infancy (SMEI) with probable autoimmune lymphoproliferative syndrome-variant.

The paper reported on a case of severe myoclonic epilepsy of infancy (SMEI) associated with a probable autoimmune lymphoproliferative syndrome variant (Dianzani autoimmune lymphoproliferative disease) (DALD). A male patient with typical features of SMEI and a SCN1A gene variant presented in the first year of life with multiple lymph nodes, palpable liver at 2 cm from the costal margin, neutropenia, dysgammaglobulinemia, relative and sometimes absolute lymphocytosis. Subsequently the patient presented with constantly raised IgA in serum and positive antinuclear and thyroid antimicrosomal antibodies. The diagnosis of probable autoimmune lymphoproliferative syndrome was made; arthritis, skin and throat blisters, which appeared subsequently led to the diagnosis of linear IgA disease. On the basis of these unique associations, the Authors hypothesized that autoimmunity may be partly responsible of the severe epileptic symptomatology, perhaps mediated by autoantibodies against sodium channels or by accompanying cytotoxic T-lymphocytes. Corticosteroid treatment ameliorated the epilepsy and laboratory tests. Future studies will be necessary to evaluate the relevance of autoimmunity in SMEI.

[Advances in the knowledge and management of autoimmune lymphoproliferative syndrome]. / Avances en el conocimiento y manejo del síndrome linfoproliferativo autoinmune.

Autoimmune lymphoproliferative syndrome (ALPS) represents a failure of apoptotic mechanisms to maintain lymphocyte homeostasis. ALPS often manifest in childhood with cytopenias, chronic non-malignant lymphoproliferation and autoimmune complications. A number of new insights have improved the understanding of the genetics and biology of ALPS. The treatment of the disease has changed and mycophenolate mofetil and sirolimus have been demonstrated to have marked activity against the disease, improving quality of life for many patients. These will be discussed in this review.

Autoimmune lymphoproliferative syndrome mimicking chronic active Epstein-Barr virus infection.

Chronic active Epstein-Barr virus infection (CAEBV) is defined as a systemic EBV-associated lymphoproliferative disease characterized by fever, lymphadenopathy, and splenomegaly in apparently immunocompetent persons. Recent studies have revealed that EBV infects T or natural killer cells in most patients with CAEBV; the etiology of CAEBV, however, remains unknown. Autoimmune lymphoproliferative disorder (ALPS) is an inherited disorder associated with defects in apoptosis, and clinically characterized by lymphadenopathy, splenomegaly, hypergammaglobulinemia, and autoimmune disease. ALPS is most often associated with mutations in the FAS gene, which is an apoptosis-signaling receptor important for homeostasis of the immune system. Based on the clinical similarity between ALPS and CAEBV with respect to lymphoproliferation, we have examined the possibility of the co-occurrence of ALPS in patients with a diagnosis of CAEBV. In this study, we have identified FAS gene mutations in three Japanese patients with lymphadenopathy, hepatosplenomegaly, and unusual EBV infection, who were diagnosed with CAEBV. These observations, which indicate that the clinical development of ALPS may be associated with EBV infection, alert us to a potential diagnostic pitfall of CAEBV.

FAS haploinsufficiency is a common disease mechanism in the human autoimmune lymphoproliferative syndrome.

The autoimmune lymphoproliferative syndrome (ALPS) is characterized by early-onset lymphadenopathy, splenomegaly, immune cytopenias, and an increased risk for B cell lymphomas. Most ALPS patients harbor mutations in the FAS gene, which regulates lymphocyte apoptosis. These are commonly missense mutations affecting the intracellular region of the protein and have a dominant-negative effect on the signaling pathway. However, analysis of a large cohort of ALPS patients revealed that ∼30% have mutations affecting the extracellular region of FAS, and among these, 70% are nonsense, splice site, or insertions/deletions with frameshift for which no dominant-negative effect would be expected. We evaluated the latter patients to understand the mechanism(s) by which these mutations disrupted the FAS pathway and resulted in clinical disease. We demonstrated that most extracellular-region FAS mutations induce low FAS expression due to nonsense-mediated RNA decay or protein instability, resulting in defective death-inducing signaling complex formation and impaired apoptosis, although to a lesser extent as compared with intracellular mutations. The apoptosis defect could be corrected by FAS overexpression in vitro. Our findings define haploinsufficiency as a common disease mechanism in ALPS patients with extracellular FAS mutations.

Mycophenolate mofetil-induced pseudotumor cerebri in a boy with autoimmune lymphoproliferative disease.

INTRODUCTION: Pseudotumor cerebri (PTC) is a syndrome characterized with increased intracranial pressure, normal cerebrospinal fluid content (CSF), and a normal brain on imaging studies. In this case report, PTC has been linked to mycophenolate mofetil (MMF) that has been used for autoimmune lymphoproliferative syndrome (ALPS). CASE REPORT: A 5-year-old boy, who was using MMF for 4 months because of the ALPS, suffered from occipital headache and vomiting with no other symptom. The initial physical examination was normal expect bilateral papilledema. The patient underwent a lumbar puncture which showed elevated opening pressure (590 mmH2O) but no laboratory abnormalities of the CSF. A diagnosis of PTC was established. MMF was stopped, and the child was started on an acetazolamide treatment for 2 weeks. His symptoms and complaints recovered after this treatment. DISCUSSION: According to our knowledge, we report the first case of MMF-induced PTC in a boy with ALPS. This case illustrates that despite the rarity of MMF-induced PTC, the physicians should be aware of this possibility. Furthermore, in the setting of new-onset headaches or visual changes, early ophthalmologic examination for papilledema is recommended for early diagnosis.

Underexpression and overexpression of Fas and Fas ligand: a double-edged sword.

OBJECTIVE: To compare autoimmune lymphoproliferative syndrome (ALPS) and Stevens-Johnson syndrome (SJS) with respect to the defects in Fas- and Fas ligand (FasL)-mediated apoptosis. DATA SOURCES: Selected reviews, case reports, and original studies were searched in PubMed and MEDLINE for the keywords ALPS, SJS, Fas, FasL, and apoptosis. STUDY SELECTION: Case reports of ALPS and SJS were selected as examples of Fas- and FasL-mediated diseases. In addition, we selected articles that examined the pathophysiology of apoptosis in the context of Fas-FasL interaction. RESULTS: Failure to initiate apoptosis of abnormal T lymphocytes occurs in such diseases as ALPS, leading to the accumulation of double negative T cells with an increase in autoimmunity. In contrast to apoptotic failure, SJS is associated with a pathological increase in programmed keratinocyte cell death. CONCLUSION: The consequences of dysregulated Fas- and FasL-mediated apoptosis leads to self-reactivity, malignant transformation, and immune dysfunction. An understanding of underlying mechanisms and qualitative assessment of Fas and FasL may have clinical benefits when control of these homeostatic mechanisms is in question.

The autoimmune lymphoproliferative syndrome: A rare disorder providing clues about normal tolerance.

The autoimmune lymphoproliferative syndrome (ALPS) is characterized by chronic, non-malignant lymphoproliferation, autoimmunity often manifesting as multilineage cytopenias, and an increased risk of lymphoma. While considered a rare disease, there are currently over 250 patients with ALPS being followed at the National Institutes of Health in Bethesda, Maryland. Most of these patients have a mutation in the gene for the TNF receptor-family member Fas (CD 95, Apo-1), and about one-third have an unknown defect or mutations affecting function of other signaling proteins involved in the apoptotic pathway. While ALPS is one of the few autoimmune diseases with a known genetic defect, there remain unanswered questions regarding how a defect in apoptosis results in the observed phenotype. In addition to shedding light on the pathophysiology of this rare and fascinating condition, studying ALPS may improve our understanding of normal tolerance and more common, sporadic autoimmune disorders.

Fas stimulation of T lymphocytes promotes rapid intercellular exchange of death signals via membrane nanotubes.

The Fas/CD95 surface receptor mediates rapid death of various cell types, including autoreactive T cells with the potential for triggering autoimmunity. Here, we present novel aspects of Fas signalling that define a 'social' dimension to receptor-induced apoptosis. Fas stimulation rapidly induces extensive membrane nanotube formation between neighbouring T cells. This is critically dependent on Rho GTPases but not on caspase activation. Bidirectional transfer of membrane and cytosolic elements including active caspases can be observed to occur via these nanotubes. Nanotube formation and intercellular exchanges of death signals are defective in T lymphocytes from patients with autoimmune lymphoproliferative syndrome harbouring mutations in the Fas receptor. We conclude that nanotube-mediated exchanges constitute a novel form of intercellular communication that augments the propagation of death signalling between neighbouring T cells.

Mutation analysis in primary immunodeficiency diseases: case studies.

PURPOSE OF REVIEW: The application of mutation analysis is becoming an integral part of the complete evaluation of patients with primary immunodeficiencies, and as such, clinicians caring for these patients must develop a better understanding of the utility and challenges of this important laboratory technology. RECENT FINDINGS: Genomic DNA sequencing is currently the standard approach used to characterize a possible gene mutation causing a specific primary immunodeficiency. There are clinical situations in which this approach is revealing of a genetic defect and other circumstances in which this generates a false-positive or false-negative result. One case study is presented that reviews a straightforward analysis that clarifies the genetic basis of a primary immunodeficiency, and four cases are presented that required additional studies to clarify the underlying basis of the immunodeficiency. In the latter circumstances, the rationale for additional studies is outlined and the outcome of these is presented. SUMMARY: The identification of a gene mutation as the underlying basis of a primary immunodeficiency begins with the evaluation of the clinical presentation focusing on the infection history so as to develop a differential diagnosis including potential genetic causes. The next step is to obtain specific laboratory studies, including immunologic function evaluation, and, based on these findings, to proceed with DNA sequencing of one or several selected candidate genes. Genomic DNA sequencing has certain limitations, and alternative follow-up approaches may be necessary to establish the molecular basis of the primary immunodeficiency in a given patient.