[Show abstract][Hide abstract] ABSTRACT: Background information:
. Microvillus inclusion disease (MVID) is a genetic disorder affecting intestinal absorption. It is caused by mutations in MYO5B or syntaxin 3 (STX3) affecting apical membrane trafficking. Morphologically MVID is characterised by a depletion of apical microvilli and the formation of microvillus inclusions inside the cells, suggesting a loss of polarity. To investigate this hypothesis we examined the location of essential apical polarity determinants in five MVID patients.
We found that the polarity determinants Cdc42, Par6B, PKCζ/ι and the structural proteins ezrin and phospho-ezrin were lost from the apical membrane and accumulated either in the cytoplasm or on the basal side of enterocytes in patients which suggests an inversion of cell polarity. Moreover microvilli-like structures were observed at the basal side in electron microscopy. We next performed Myo5B depletion in 3D-grown human Caco2 cells forming cysts and we found a direct link between the loss of Myo5B and the mislocalisation of the same apical proteins; furthermore we observed that a majority of cyst displayed an inverted polarity phenotype as seen in some patients. Finally we found that this loss of polarity was specific for MVID: tissue samples of patients with Myo5B independent absorption disorders showed normal polarity but we identified Cdc42 as a potentially essential biomarker for tricho-hepato-enteric syndrome.
Our findings indicate that the loss of Myo5B induces a strong loss of enterocyte polarity, potentially leading to polarity inversion.
Our results show that polarity determinants could be useful markers to help establishing a diagnosis in patients. Furthermore they could be used to characterise other rare intestinal absorption diseases. This article is protected by copyright. All rights reserved.
Full-text · Article · Nov 2015 · Biology of the Cell
[Show abstract][Hide abstract] ABSTRACT: Mismatch-repair (MMR)-deficient cells show increased in vitro tolerance to thiopurines because they escape apoptosis resulting from MMR-dependent signaling of drug-induced DNA damage. Prolonged treatment with immunosuppressants including azathioprine (Aza), a thiopurine prodrug, has been suggested as a risk factor for the development of late onset leukemias/lymphomas displaying a microsatellite instability (MSI) phenotype, the hallmark of a defective MMR system. We performed a dose effect study in mice to investigate the development of MSI lymphomas associated with long term Aza treatment. Over two years, Aza was administered to mice that were wild type, null or heterozygous for the MMR gene Msh2. Ciclosporin A, an immunosuppressant with an MMR-independent signaling, was also administered to Msh2wt mice as controls. Survival, lymphoma incidence and MSI tumor phenotype were investigated. Msh2+/- mice were found more tolerant than Msh2wt mice to the cytotoxicity of Aza. In Msh2+/- mice, Aza induced a high incidence of MSI lymphomas in a dose-dependent manner. In Msh2wt mice, a substantial lifespan was only observed at the lowest Aza dose. It was associated with the development of lymphomas, one of which displayed the MSI phenotype, unlike the CsA-induced lymphomas. Our findings define Aza as a risk factor for an MSI-driven lymphomagenesis process.
[Show abstract][Hide abstract] ABSTRACT: Anti-hypertensive treatment with the angiotensin II receptor antagonist olmesartan is a rare cause of severe Sprue-like enteropathy. To substantiate the hypothesis that olmesartan interferes with gut immune homeostasis, clinical, histopathological and immune features were compared in olmesartan-induced-enteropathy (OIE) and in autoimmune enteropathy (AIE).
Medical files of seven patients with OIE and 4 patients with AIE enrolled during the same period were retrospectively reviewed. Intestinal biopsies were collected for central histopathological review, T cell Receptor clonality and flow cytometric analysis of isolated intestinal lymphocytes.
Among seven olmesartan-treated patients who developed villous atrophy refractory to a gluten free diet, three had extra-intestinal autoimmune diseases, two had antibodies reacting with the 75 kilodalton antigen characteristic of AIE and one had serum anti-goblet cell antibodies. Small intestinal lesions and signs of intestinal lymphocyte activation were thus reminiscent of the four cases of AIE diagnosed during the same period. Before olmesartan discontinuation, remission was induced in all patients (7/7) by immunosuppressive drugs. After interruption of both olmesartan and immunosuppressive drugs in six patients, remission was maintained in 4 but anti-TNF-α therapy was needed in two.
This case-series shows that olmesartan can induce intestinal damage mimicking AIE. OIE usually resolved after olmesartan interruption but immunosuppressive drugs may be necessary to achieve remission. Our data sustain the hypothesis that olmesartan interferes with intestinal immuno regulation in predisposed individuals.
[Show abstract][Hide abstract] ABSTRACT: Detection of MUM1+ cells in follicular lymphoma (FL) tissues was previously found to be associated with poor prognosis in a single report; whereas the usefulness of Ki67 immunostaining remains debated. Our goal was to establish whether these markers have predictive value for FL patients. We analyzed MUM1 and Ki67 expression using immunohistochemistry (IHC) in biopsy samples from 434 patients from the PRIMA randomized trial. The MUM1 prognostic value was then validated in a cohort of 138 patients from the FL2000 randomized trial, using the optimal cut-off value obtained from the PRIMA cohort. The surface of positive staining was quantified using computerized image analysis (CIA). In the PRIMA cohort, both high levels of MUM1 positivity (cut-off value of 0.80%) and high levels of Ki67 positivity (cut-off value of 10.25%) were significantly associated with a shorter progression free survival (PFS) (P=.004 and P=.007 for MUM1 and Ki67, respectively). In a multivariate Cox proportional hazards regression model, only MUM1 retained a statistical significance (HR=1.56, 95% CI 1.02-2.37, P=.038) after adjustment for the maintenance arm of treatment and the FLIPI score. In the FL2000 cohort, high levels of MUM1 positivity were significantly associated to a shorter PFS (P=.004) and to a trend toward a shorter overall survival (OS) (P=.043). This remained significant using a multivariate Cox regression model after adjustment for the FLIPI and the treatment arm for PFS (P=.016). These results show that MUM1 is a strong and robust predictive IHC marker in FL patients.
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: Inflammatory bowel disease (IBD) is one of the most common chronic gastrointestinal diseases, but the underlying molecular mechanisms remain largely unknown. Studies of monogenic diseases can provide insight into the pathogenesis of IBD.
OBJECTIVE:We thought to determine the underlying molecular causes of IBD occurring in 2 unrelated families in association with an immune deficiency.
METHODS: We performed genetic linkage analysis and candidate gene sequencing on 13 patients from a large consanguineous family affected by early-onset IBD, progressive immune deficiency, and, in some cases, autoimmunity and alopecia, a condition we named enteropathy-lymphocytopenia-alopecia. The candidate gene was also sequenced in an unrelated patient with a similar phenotype. We performed histologic analysis of patients' intestinal biopsy specimens and carried out functional assays on PBMCs. Gut organoids derived from a patient's biopsy specimen were analyzed.
RESULTS: We identified biallelic missense mutations in tetratricopeptide repeat domain 7A (TTC7A) in all patients from both families. The resulting TTC7A depletion modified the proliferation, adhesion, and migratory capacities of lymphocytes through inappropriate activation of the RhoA signaling pathway. Normal function was restored by wild-type TTC7A expression or addition of a RhoA kinase inhibitor. The growth and polarity of gut epithelial organoids were also found to be dependent on the RhoA signaling pathway.
CONCLUSIONS: We show that TTC7A regulates the actin cytoskeleton dynamics in lymphocytes through the RhoA signaling pathway and is required in both lymphocytes and epithelial cells for maintaining equilibrium between cell proliferation, migration, polarization, and cell death. Our study highlights variability in the phenotypic expression resulting from TTC7A deficiency and outlines that impairment of both epithelial cells and lymphocytes cooperatively causes IBD.
Full-text · Article · Aug 2014 · Journal of Allergy and Clinical Immunology
[Show abstract][Hide abstract] ABSTRACT: Autoimmune lymphoproliferative syndrome (ALPS) caused by impaired FAS-mediated apoptosis of lymphocytes is characterized by lymphoproliferation, autoimmunity, but also an increased risk of invasive bacterial infection, notably following splenectomy. We surveyed a cohort of 100 ALPS patients (including 33 splenectomized) and found that 12 (10 splenectomized) had experienced 23 invasive bacterial infections mainly caused by Streptococcus pneumoniae. This vulnerability was associated with evidence of defective B-cell function characterized by low serum IgM, low IgM antibody production in response to S.pneumoniae following non-conjugated immunization and low blood memory B-cells counts (including marginal zone (MZ) B-cell counts). This immunodeficiency strongly correlated with intensity of lymphoproliferation. Spleen sections from nine ALPS patients revealed double-negative T-cell (DN-T) infiltration of the MZ, which was depleted of B-cells. MZ in ALPS patients contained an abnormally thick layer of MAdCAM-1 (+) stromal cells and an excess of DN-T cells. DN-T were shown to express MAdCAM-1 ligand, alpha4-beta7 integrin. These observations suggest that accumulating DN T-cells are trapped within stromal cell meshwork and interfere with correct localization of MZ B-cells. Similar observations were made in spleen of fas-deficient mice. Our data revealed an unexpected mechanism by which ALPS results in antipolysaccharide IgM antibody production specific defect. Splenectomy should be avoided.
[Show abstract][Hide abstract] ABSTRACT: Crohn disease is an inflammatory bowel disease (IBD) with a complex mode of inheritance. Although nucleotide binding and oligomerization domain containing 2 (NOD2) is the strongest risk factor, the cause of Crohn disease remains unknown in the majority of the cases. X-linked inhibitor of apoptosis (XIAP) deficiency causes X-linked lymphoproliferative syndrome type 2. IBD has been reported in some XIAP-deficient patients.
Full-text · Article · Jun 2014 · Journal of Allergy and Clinical Immunology
[Show abstract][Hide abstract] ABSTRACT: Background
Lymphomatoid Papulosis (LyP) is an uncommon cutaneous T-cell lymphoproliferative disorder (CTLPD) rarely encountered in children.Objective: To specify characteristics of paediatric LyP and to describe both diagnostic difficulties and course of the disease with the experience of 10 years follow up.Patients and Methods
This was a retrospective, single-center study of twenty-five children diagnosed with LyP according to the 2008 World Health Organization guidelines, and a clinical and pathological correlation by two experts.ResultsThe mean age at the onset was 7y 6m. The lesions were mostly papulonodular with frequent pruritus (40%). A mucosal involvement could be observed. A single ulcerate nodule was initially suggestive of a primary cutaneous anaplastic large cell lymphoma (C-ALCL). Pityriasis lichenoides was associated in 36% of cases, atopic dermatitis in 28% and non specific infections in 28%. Complete remission was observed in 44% of cases. Through the mean follow-up of 10 years,none of our patients have experienced lymphoma occurence. Histopathologic subtype A clearly predominated (82%). A marked eosinophilic infiltrate was present in 44% and a cutaneous T gamma clone in 40%. No correlation was observed between histopathologic subtype, cutaneous clone or LyP clinical course.Limitations: retrospective studyConclusion
Paediatric LyP belongs to CD30-positive CTLPD including C-ALCL. Children have to be carefully life-long followed-up even if the prognosis appears good. The high frequency of an associated viral infection, atopic dermatitis, marked eosinophilic infiltrate and a good outcome suggests that paediatric LyP could be considered as a reactional disease rather than a malignant disorder.This article is protected by copyright. All rights reserved.
No preview · Article · Apr 2014 · British Journal of Dermatology
[Show abstract][Hide abstract] ABSTRACT: Subcutaneous panniculitis-like T-cell clonal proliferation is commonly seen as a cytotoxic subcutaneous lymphoma arising mainly in adults. This type of lymphoid proliferation in children, particularly in infants, is extremely rare. In most such cases, the prognosis is excellent even if it is associated with a hemophagocytic syndrome (HPS). Some cases may even regress spontaneously. The case presented here concerns a 6-month-old infant who presented with panniculitis lesions associated with an HPS that started 1 week after a chickenpox infection. The histologic findings showed a marked lobular panniculitis with extensive hyaline necrosis of adipocytes and massive infiltration of clonal small-to-medium lymphocytes with a cytotoxic, CD56−, β-F1+ phenotype. In addition, the same lymphocytic proliferation was also observed in the upper dermis and the epidermis. Complete and stable remission of both cutaneous lesions and systemic manifestations was obtained with nonaggressive therapy consisting of systemic steroids followed by cyclosporin A. This observation demonstrates that in a young child, a clonal T-cell lymphoproliferation in the skin, even when it has an aggressive histologic appearance and is combined with an HPS, need to not be managed aggressively with chemotherapy. Because the disorder began a few days after a viral infection, it should be seen as a reactive clonal T-cell lymphoproliferation rather than a true T-cell lymphoma.
No preview · Article · Jan 2014 · Pathology Case Reviews
[Show abstract][Hide abstract] ABSTRACT: Little is known about intestinal CD4+ T-cell lymphoma; this rare malignancy is frequently misdiagnosed. We evaluated diagnostic criteria and factors that might affect its development and outcome.
In a retrospective analysis, we analyzed medical records and intestinal specimens from 10 patients diagnosed with intestinal CD4+ T-cell lymphoma among 115 consecutive patients examined for severe enteropathy with villous atrophy. Samples were analyzed by histology, flow cytometry, and comparative genomic hybridization.
Small intestine epithelial and lamina propria tissues from patients who presented with chronic diarrhea and malnutrition had variable levels of infiltration of the by CD3+ CD4+ T cells. Flow cytometry revealed a high frequency of CD4+ intra-epithelial cells, which frequently expressed a specific Vβ chain. T-cell receptor β clonality was confirmed by DNA sequencing. Two patients had HLA and serology results compatible with celiac disease and autoimmune enteropathy, respectively. Two patients were found to have antibodies against human T-cell leukemia virus and 2 patients had signs of recent infection with herpes viruses. Comparative genomic hybridization analyses showed heterogeneous chromosomal abnormalities. Symptoms were reduced in patients treated with steroids (n=5), but not in patients given purine analogues or chemotherapy. Antibodies against CD52 produced clinical and histological responses in 2/2 patients, whereas severe adverse effects developed in 1 patient. At the latest follow up, all patients are alive.
There is much heterogeneity in onset and genetic features of intestinal CD4+ T cell lymphomas, despite their common presentation as indolent lymphoproliferations of the intestinal mucosa. Patients should be treated with steroids, and possibly antibodies against CD52 (for the most aggressive forms of this disorder).
No preview · Article · Dec 2013 · Clinical gastroenterology and hepatology: the official clinical practice journal of the American Gastroenterological Association
[Show abstract][Hide abstract] ABSTRACT: Multiple intestinal atresia (MIA) is a rare cause of bowel obstruction that is sometimes associated with a combined immunodeficiency (CID), leading to increased susceptibility to infections. The factors underlying this rare disease are poorly understood. We characterized the immunological and intestinal features of 6 unrelated MIA-CID patients. All patients displayed a profound, generalized lymphocytopenia, with few lymphocytes present in the lymph nodes. The thymus was hypoplastic and exhibited an abnormal distribution of epithelial cells. Patients also had profound disruption of the epithelial barrier along the entire gastrointestinal tract. Using linkage analysis and whole-exome sequencing, we identified 10 mutations in tetratricopeptide repeat domain-7A (TTC7A), all of which potentially abrogate TTC7A expression. Intestinal organoid cultures from patient biopsies displayed an inversion of apicobasal polarity of the epithelial cells that was normalized by pharmacological inhibition of Rho kinase. Our data indicate that TTC7A deficiency results in increased Rho kinase activity, which disrupts polarity, growth, and differentiation of intestinal epithelial cells, and which impairs immune cell homeostasis, thereby promoting MIA-CID development.
Full-text · Article · Dec 2013 · The Journal of clinical investigation
[Show abstract][Hide abstract] ABSTRACT: Congenital tufting enteropathy (CTE) is a rare and severe enteropathy recently ascribed to mutations in the epcam gene. Here we establish SPINT2, previously ascribed to congenital sodium diarrhea, as a second gene associated with CTE and report molecular and immunohistochemistry data in 57 CTE patients. Inclusion criteria were early onset diarrhea and intestinal insufficiency with the typical histological CTE abnormalities. The clinical phenotype was registered, the entire coding regions of epcam and SPINT2 sequenced, and immunostaining of EpCAM and SPINT2 performed on intestinal biopsies. An epcam mutation was involved in 41 patients (73 %) who mainly displayed isolated digestive symptoms. Mutations severely affected gene expression since the EpCAM signal on intestinal tissues was either undetectable or low and irregular. Twelve other patients (21 %) carried mutations in SPINT2, and were phenotypically characterized by systematic association with keratitis (p < 10(-4)) and, for half of them, with choanal atresia (p < 10(-4)). Dependency on parenteral nutrition (PN) was comparable in patients with epcam or SPINT2 mutations, but the frequent epcam mutation c.556-14A>G (abnormal splicing) was significantly associated with a better outcome (p = 0.032) with milder PN dependency to weaning in some cases. Finally, four patients (7 %) with isolated digestive symptoms had no detectable epcam or SPINT2 mutation. Two candidate genes, Elf3 and Claudin7, were excluded from this population. Our study allows us to separate CTE patients into at least three genetic classes, each with specific phenotypes. The genetics approach raises the question of the distinction between two congenital enteropathies. Our findings should help improve the diagnosis of CTE, guide toward strategies of long-term PN management, and limit indications for intestinal transplantation to life-threatening PN complications.